吉田 友昭

The specificities of the antisera raised in the CDF1 mice that had been immunized with the P1.HTR tumor cells xenogenized by transfection with recombinant H-2Kb-erbB gene were studied. The antisera cross-reacted with a broad range of tumor cell lines maintained either in vitro or in vivo in an immunofluorescence assay. However, they did not react at all with syngeneic normal tissue cells from thymus, spleen, bone marrow and fetal liver. Even though antigens related to the murine leukemia virus and murine mammary tumor virus (MuMTV) were demonstrated in many of the tumor cell lines tested with specific antibodies, these antigens did not seem to be primarily involved in the anti-P1.HTR antibody activity. The 74 kDa molecule, which was precipitated by the anti-P1.HTR anti-serum from the surface radiolabeled cell extract of P1.HTR tumor and was discriminated from the 70 kDa molecule precipitated by the anti-MuMTV serum, was widely distributed among various tumor cell lines tested, but was absent in normal tissue cells. In contrast to the extensive cross-reaction by the antibody, the cytotoxic T lymphocyte generated in the P1.HTR immune mice were shown to be specific to the P1.HTR tumor, and the 98 kDa molecule was precipitated by the anti-P1.HTR serum from the P1.HTR tumor but not from other tumors tested. It is suggested from these results that the 98 kDa molecule is a candidate for an individual tumor-specific transplantation antigen, and is immunodominant for inducing cytotoxic T lymphocytes to coexisting intrinsic retroviral antigens and other serologically cross-reactive tumor antigens.

We demonstrated that heat-killed Corynebacterium liquefaciens bacteria, as a known potent host immune activity modulator, stimulate spleen cells to produce granulocyte-macrophage (GM) colony-stimulating factor (CSF) and another CSF with similar activity, as well as alpha/beta interferon, when injected intravenously into mice. Alpha/beta interferon was shown to be produced by C. liquefaciens-activated plastic-G-10 column-adherent cells (A cells) in a thymus-independent manner. In contrast, augmented production of GM-CSF required the action of C. liquefaciens-activated T lymphocytes that collaborated with normal A cells. Non-T spleen cells from C. liquefaciens-stimulated athymic mice, however, produced an alternative CSF that partially replaced GM-CSF. Correspondingly, the numbers of GM-producing CFU developing in cultures of spleen cells from C. liquefaciens-treated euthymic or athymic mice were 10 to 30 times higher than those in cultures of spleen cells from untreated mice. These results suggest that gram-positive rods such as C. liquefaciens activate T and A cells for production of multiple cytokines and that potential cooperative actions of these cytokines underlie the known immunomodulatory action of coryneforms.

We have developed a two-dimensional (2-D) mapping of pyridylaminated oligosaccharides as an aid to structural determination of glycoprotein-derived oligosaccharides. Using the available data of reverse-phase HPLC of pyridylamino-oligosaccharides, this was further extended to parameterization of unit contribution by each sugar component, which allows the prediction of possible structures from the elution volume. We have extended this approach to the data obtained with amide-silica HPLC column to obtain a calculated 2-D mapping technique for the oligomannose-type oligosaccharides (M-series). In this method, the elution volumes of all possible pyridylamino-oligosaccharides up to the size of Glc1Man9GlcNAc2 (50 in total) are calculated from the established UC values to construct a 2-D map. To test the validity of the calculated 2-D map, the structures of intermediate PA-oligosaccharides generated during the alpha-mannosidase (jack bean) digestion of Man9GlcNAc2 (porcine thyroglobulin) were analyzed to establish the digestion pathway. The validity of this approach is substantiated by an independent deduction of the intermediate structures based on structural relationships and the coincidence of elution volumes. Our results agree well with the recently published digestion pathway of Man5GlcNAc2 by the same enzyme and that of Man9GlcNAc2 by lysosomal alpha-mannosidase.

Studies on allotype-linked immune response genes and related genes are overviewed with particular attention to our current results in unique models. Significance of actions of various immune response genes in relation to allelic polymorphism of molecules in the immune system is discussed. The molecules involve immunoglobulins, T cell receptors, major histocompatibility complex and a number of cell interaction molecules, many of which belong to the immunoglobulin superfamily. Differential roles of V-linked and C-linked immune response genes for network control of the immune system, preparing the V structure repertoire, controlling antigen presentation and modulating the effector mechanism, are suggested.

The lymphocyte signal transduction, as determined by intracellular free Ca2+ mobilization of concanavalin A-stimulated T lymphocytes and of anti-immunoglobulin mu chain antibody-stimulated B lymphocytes, was suppressed in spleen cells from mice injected with murine P1.HTR mastocytoma-induced ascites and in spleen cells treated with the ascites in vitro. The suppression was observed both at the peak level and in the reactive pattern of Ca2+ influx. In the suppression, the ascites were replaceable with tumor culture supernatants or tumor homogenates. Correspondingly, primary and secondary cytotoxic T lymphocyte (CTL) responses of DBA/2 mice to allogeneic antigen were also significantly suppressed by injection of the syngeneic P1.HTR tumor-derived ascites. This new finding suggested that the mechanism of the tumorous ascites or of the tumor-derived factor-mediated immunosuppression involves at least in part the suppression of the early event of the signal transduction for lymphocyte activation.

Glycyrrhizin (GL), a saponin fraction of licorice with defined chemical structure, was shown to display a definite action in vitro augmenting the cell-surface expression of H-2 class I antigens as well as class I gene transcription on various tumour cell lines. The magnitude of augmentation was varied among eight different cell lines tested, but reached more than three times. It was also found that GL enhanced the expression of H-2Dd antigens in some normal cell populations in vivo. The augmentation of H-2 class I antigens on tumour cell lines in vitro was probably not mediated by the interferon, which might have been produced by the cultured cells. These findings may suggest a new immunopharmacological action of GL.

We have successfully produced transgenic mice that carry the ret oncogene driven by a mouse mammary tumor virus promoter/enhancer. Mammary and salivary gland adenocarcinomas were developed in a stochastic fashion in these mice. Moreover, premalignant tumors with hyperplastic and dysplastic lesions of Harderian glands and male reproductive tracts frequently occurred at young ages. High expression of the transgene was closely associated with the development of these tumors although the levels of the transgene expression were variable among individuals. In addition, large amounts of phosphotyrosine-containing proteins were detected in cell lysates from mammary and salivary adenocarcinomas by immunoblotting with the anti-phosphotyrosine antibody.

The chimeric mouse MHC class I gene derived from a recombinant H-2Kb gene, in which the coding region for a large part of alpha 1 and alpha 2 extracellular domains was replaced with a partial avian erythroblastosis virus erbB gene segment encoding the kinase domain, was successfully introduced into a mouse mastocytoma line P1.HTR (H-2d) and transcribed to mRNA. The transfectant cells expressed the chimeric gene product, which was reactive to a phosphotyrosine-specific antibody. When the chimeric gene transfectant was inoculated into CDF1(H-2d) or BDF1(H-2d/b) mice, it grew at an early time but regressed thereafter. Transfectant-specific as well as parental P1.HTR-specific antibody activities were demonstrated in the sera of these mice. Transfectant-specific cytotoxic T lymphocytes (CTL) were generated in the antigen-sensitized culture of spleen cells from the transfectant-immune mice. The CTL-mediated lysis of target chimeric gene transfectant cells was poorly inhibited by anti-H-2d antiserum, which blocked the lysis of parental P1.HTR cells by anti-tumor CTL developed in parallel. The former was, however, inhibited by either anti-transfectant antiserum or anti-phosphotyrosine antibody, which was ineffective for blocking the latter. Target cell lysis by either anti-transfectant or anti-tumor CTL was blocked by anti-CD8 monoclonal antibody but not by anti-CD4 antibody. It was suggested from these results that the H-2K-erbB hybrid gene product, which lacks complete three-domain class I structure, was recognized by CTL in a manner that was endogenous H-2 class I-independent but CD8-dependent.

The recombinant H-2Kb-erbB gene, encoding for a part of the H-2 class I antigen and the kinase domain of the V-erbB peptide, was successfully introduced into murine mastocytoma P815 variant P1.HTR cells, which resulted in low but significant cell-surface expression of the hybrid gene product. When the chimeric gene transfectant was inoculated into the CDF1 mice, it soon grew but regressed thereafter. The tumorigenicity of this transfectant was lower than the H-2Kb gene transfectant that expressed the H-2Kb antigen at a comparable level. These CDF1 mice that had received the chimeric gene transfectant obtained a high-grade anti-tumor immunity against the challenge of a high dose of parental tumor. Corresponding to these observations, anti-tumor cytotoxic T lymphocytes, which lyse parental P1.HTR cells but not syngeneic L1210 or NS-1 tumor cells, were developed in the peritoneal cavity of mice that had been inoculated with the transfectant and parental tumor. Definite antibody activity binding to parental P1.HTR tumor cells was also demonstrated in the sera of these mice, precipitating 40-kDa, 74-kDa and 98-kDa molecules from the surface of the radiolabeled P1-HTR tumor cells. The results suggested that the chimeric H-2-erB gene transfectant efficiently triggers both cellular and humoral anti-tumor immune responses.

Some R-mutant Escherichia coli and Salmonella heavily adhered to murine lymphoma cells of B cell and T cell lineages. This adhesion was primarily mediated by membrane-localized proteins on tumor cells, which bind the polymyxin B-reactive hydrophilic structure of lipis A on bacteria. SDS-PAGE analysis of tumor cell membranes showed that proteins or glycoproteins of MW = around 45Kd, 25-35Kd and around 15Kd preferentially bind lipid A. Various lymphoma cell lines binding the bacteria at different levels possessed lipid A-binding proteins of slightly different compositions. We conclude that lymphoma cells carry not a single but a group of lipid A-binding proteins in their membranes.

The mode of alloantibody-mediated inhibition of allo-sensitization for tumor allograft rejection was studied. Relatively small amounts of anti-H-2d alloantiserum administered shortly before or after injection of allogeneic spleen cells blocked the allo-sensitization for second-set tumor allograft rejection. In contrast, the alloantiserum injected shortly before inoculation of tumor barely enhanced the tumor growth. The passively administered alloantiserum inhibited the sensitization for allospecific cytotoxic T lymphocyte responses in vitro. Further study revealed that the allo-sensitization could be blocked with antiserum specific against only one of the expressed H-2 antigens on stimulator cells. Correspondingly, H-2Dd-monospecific monoclonal antibody (IgG2a) was effective in inhibiting the sensitization with cells expressing multiple H-2 alloantigens. These results suggest that antibody-mediated inactivation of stimulator cells as a whole is an important mechanism of the allograft enhancement.

Thymocyte membrane fragments (TMF) but not brain cell membrane fragments (BMF) show a unique activity for inducing Thy-1 alloantibody response. Treatment of TMF with alpha-mannosidase or endoglycosidase-H greatly diminished this activity but not the serological Thy-1 antigenicity. This suggested that the TMF activity is supported by high mannose type N-linked oligosaccharides on the TMF. On the other hand, treatment with neuraminidase made otherwise silent BMF definitely active for the antibody response and this activity was abolished by further treatment with endoglycosidase-D. This demonstrated that BMF have a latent activity which is mediated by complex type N-linked oligosaccharides normally masked with sialic acids. It was concluded that two types of N-linked oligosaccharides as well as sialic acids mediate at least in part the tissue type-specific membrane activity for Thy-1 alloantibody response.

Immunogenicity of allogeneic immunoglobulins in mice were studied, measuring the allotype-specific antibody activity by agglutination of allogeneic antibody-coated red blood cells. It was found that the serum from C.B-20 mice (Ighb, BALB/c-congenic) was uniquely immunogenic in BALB/c mice for allotype antibody response. Whereas the C57BL/6 (Ighb) serum was immunogenic only when heat aggregated and/or combined with adjuvant, the ultracentrifugation-deaggregated C.B-20 serum was definitely immunogenic when administered in a moderate dose (100 microliters/mouse). Even more surprising was the fast that very low doses (0.01-0.1 microliter) of soluble C.B-20 serum, but not C57BL/6 serum, down regulated the allotype-specific response effectively. Genetic analysis on congenic mice suggested that the immunogenicity is controlled by donor Igh or Igh-V (Id-C.B) inasmuch as the serum from BALB/c-congenic C.B-20 (Igh-VbCb), but not BALB/c-congenic BAB/14 (Igh-VaCb), mice was active in BALB/c mice in soluble form. Further studies showed that the Id-C.B was dominantly expressed on the immunoglobulins of (BALB/c x C.B-20)F1 and (C56BL/6 X C.B-20)F1 strains, and was originally derived from the C57BL/Ka strain. The major determinant for the antibody production was encoded in Igh-C, but not in Igh-V. It is suggested that Id-C.B controls the allotype-specific antibody response in an unusual manner, possibly acting as a unique determinant activating helper T cells.

By adding IL-2 (supernatant of culture of concanavalin A-activated rat spleen cells) on Day 3 of mixed leucocyte cultures (MLC) we managed to fully activate multiple minor histocompatibility antigen (MIHA)-specific cytotoxic T-lymphocyte precursors (CTLp). In this newly developed system we studied genetic and stimulator cell requirements for the generation and activation of MIHA-specific memory CTLp. Memory CTLp were activated to generate effector CTL in MLC only when major histocompatibility complex (MHC)-compatible MIHA-allogeneic cells were used as stimulators. In contrast, memory CTLp were generated in mice that were primed by injection of either MHC-compatible or incompatible MIHA-allogeneic spleen cells. A surprisingly small number (10(4] of MHC-disparate cells cross-primed mice effectively. For priming, no special accessory cell types were required as stimulators, and 10(4) adherent cell-depleted spleen cells primed mice as well. These results contrasted to another finding that sonication-disrupted 10(6) stimulator cells did not prime mice effectively, and antigens shed from 10(7) live stimulator cells failed to sensitize host antigen-presenting cells for priming. It is suggested from these results that the mode of recognition of MIHA by virgin CTLp is unique or that an as yet unknown unusual stimulation pathway works for the priming.

Intravenous injection of killed Corynebacterium liquefaciens induced a population of red blood cells that expressed both H-2K and H-2D antigens at exceptionally high density and displayed augmented immunogenicity for H-2 alloantigen-specific B cell activation. Injection of killed Escherichia coli or E. coli lipopolysaccharide was ineffective for the generation of such RBC. RBC that express H-2 antigens at high density first appeared at 7 days after injection of C. liquefaciens. These RBC persisted for more than 50 days, although they lost H-2 antigens gradually with time. The observed phenomenon was not due to enhanced erythropoiesis and peripheral release of immature RBC (reticulocytes); populations of both mature and immature RBC of mice injected with C. liquefaciens expressed H-2 antigens at high density, whereas those from normal mice or mice injected with phenyl hydrazine did not. Appearance of RBC expressing H-2 antigens at high density was preceded by a temporal increase in H-2 expression of bone marrow cells that included precursors of RBC. It was concluded that RBC expressing H-2 antigens at high density were descendants of bone marrow cells whose H-2 expression was augmented by C. liquefaciens. The present communication would be the 1st report of the bacteria-mediated augmentation of cell surface expression and activity of major-histocompatibility-complex class I antigens on host cells in vivo.

The dynamics of cytotoxic T lymphocyte precursors (CTL-p) in mice injected with allogeneic spleen cells (SC) was studied with special reference to changes in their radiation sensitivity. Whole-body 400 rad X-ray irradiation of allo-SC-primed and unprimed mice virtually abolished the capacity of their SC to proliferate and to generate CTL in primary or secondary mixed leucocyte culture (MLC). However, the impaired ability of SC to generate CTL in the primary MLC was restored by interleukin 2 (IL-2). This showed that helper cells whose activity was replaceable with IL-2 (IL-2-producing cells) were functionally more radiation-sensitive than CTL-p in unprimed mice. In contrast, the radiation-impaired activity in secondary MLC was not restored by IL-2, suggesting that memory CTL-p in allo-SC-primed mice were unexpectedly sensitive to radiation. The D37 values determined from the percentage of residual CTL-p activity of SC in bulk cultures 1 day after irradiation were 525 rad for virgin CTL-p and 75 rad for memory CTL-p. Further studies demonstrated that the radiation-sensitive memory CTL-p were generated from relatively radiation-resistant precursors, largely independent of radiation-sensitive IL-2-producing cells and of cellular proliferation. The mean frequency of CTL-p in SC measured by limiting dilution assay was not significantly increased by the priming. This supports our conclusion that the development of the memory CTL-p activity in allo-SC-primed mice did not depend on clonal expansion. Whole-body 400 rad-irradiation reduced the frequency of CTL-p in SC from unprimed mice to 1/2-1/3 and that in SC from allo-SC-primed mice to 1/8-1/15. This supports the view that the majority of radiation-resistant virgin CTL-p functionally mature to radiation-sensitive memory CTL-p without cellular proliferation in allo-SC-primed mice.

Transplantation immunity for second-set rejection of an allogeneic ascites tumor was induced by sensitizing mice with H-2-identical allogeneic spleen cells, and radiation-sensitivity of this immunity was studied. The immunity was not severely affected by 400 rads whole-body X-ray irradiation given at one day before the initial antigenic stimulation. In contrast, it was totally inactivated by 300-400 rads irradiation that was given one day before tumor challenge. An adoptive cell transfer experiment showed that alloreactive memory cells responsible for the immunity were unexpectedly highly radiosensitive. The immunity (memory), however, became resistant to 400 rads irradiation soon (one day) after challenge with the allogeneic tumor, and was resistant to 1500 rads for rejection of the tumor that was challenged at the second time when the initially challenged tumor was rejected. Corresponding to these observations, cells for allospecific CTL responses in peritoneal cavity of mice showed corresponding biphasic radiation-sensitivity.

A definite cytotoxic activity was developed in a BALB/c (H-2d) anti-DBA/2 primary mixed leukocyte culture (MLC), which received interleukin 2 (IL-2) on day 3 of culture. This cytotoxic activity was minor histocompatibility antigens (MIHA)-specific at the stimulator level, and was not developed in a syngeneic (BALB/c anti-BALB/c) MLC. The addition of IL-2 on day 3 of culture was crucial; no or very weak cytotoxic activity was developed in MLC receiving IL-2 on day 0 or on both day 0 and day 3. Only appropriate MIHA-allogeneic tumor cells were lysed as the target of the cytotoxic activity. The cytotoxic activity seemed MIHA-specific also at the target level; it lysed tumor cells of DBA/2 mouse origin but not those of BALB/c (syngeneic) origin. Phenotypes of the cytotoxic effector cell were Thy-1+ Lyt-2+. We concluded from these results that MIHA-specific cytotoxic T lymphocytes (CTL) were generated in the MIHA-allogeneic primary MLC. In this newly developed system, we studied genetic and antigenic requirements for primary anti-MIHA CTL responses in vitro. We demonstrated; among spleen cells (SC) of seven B10 H-2-congenic strains only SC of B10.D2 strain whose major histocompatibility complex (MHC) (H-2d) was compatible with the responder MHC effectively stimulated responder BALB/c (H-2d) SC for an anti-MIHA (DBA-C57BL-common) CTL response. Similarly, only SC of two out of seven C x B recombinant inbred strains (C x B.H and C x B.D), which were compatible at the MHC with responder SC, activated responder BALB/c SC for the response. The possibility that cells responding to H-2 alloantigens suppressed the anti-MIHA response was ruled out. Additional experiments showed that compatibility at the H-2K-end or the H-2D-end of the MHC was sufficient for a definite anti-MIHA response. These provided formal evidence that primary anti-MIHA CTL responses in vitro were MHC-restricted at the stimulator level. We then showed that sonication-disrupted SC or Sephadex G-10 column-passed nonadherent SC failed to stimulate responder SC for a primary anti-MIHA CTL response, whereas G-10-passed nonadherent SC responded well to adherent stimulator cells. Further study demonstrated that Ia+ adherent cells were the most active cell type as stimulator. Finally, we confirmed that the primary anti-MIHA CTL responses to adherent stimulator cells was MHC-restricted.

Originally T-cell clone K7L-sensitive L1210 murine leukemia clones were tested for their capacity to generate K7L-insensitive variants at various times after cloning. All of the L1210 clones (L1210/1, -2, -4, and -7) maintained in vitro for 1 month were severely inhibited in their growth in the culture in which K7L was added and in mice given injections of K7L at the initial stage. This indicated that any L1210 clone tested was not a mixture of K7L-sensitive and K7L-insensitive clones at the time of cloning. By both in vivo and in vitro K7L-mediated tumor suppression assays, K7L-insensitive antigen loss variants were then found to be generated from some (L1210/4, L1210/7) but not other (L1210/1, L1210/2) originally K7L-sensitive L1210 clones during 1 month of maintenance. Ratios of variant cells to total clone cells 1 month after cloning were estimated around 0.1% for L1210/7, 0.01% for L1210/4, and less than 0.001% (undetectable) for L1210/1 and L1210/2. Neither L1210/1 nor L1210/2 generated detectable K7L-insensitive variant cells during long-term (14-month) maintenance. All of the ten subclones of L1210/7 which were obtained 7 or 11 months after the initial cloning of L1210/7 were K7L sensitive, and not all the subclones generated K7L-insensitive variants in 1-2 months of maintenance after recloning. However, all of the subclones of L1210/7 which were maintained for 7 months generated antigen loss variants. All eight clone cells obtained from original L1210 and K7L-insensitive L1210 expressed H-2Kd and H-2Dd antigens detected by H-2Kd or Dd-specific cytotoxic T-lymphocyte clones or monoclonal antibodies. These results suggest that the antigen loss variants arise in originally K7L-sensitive L1210 clones at different times after cloning, and the probability of generation of the variants is clonally determined. The antigen loss variants seem to be generated by rare (once per 1 to 2 months or less frequent) chance with unproportionally rapid growth rather than by more frequent development for simple accumulation. The ratio of K7L-insensitive variant cells to total L1210/7 cells did not increase progressively during long-term (13 months or more) maintenance in vivo or in vitro and was always below 0.1%. It was suggested that the population size of antigen loss variants was controlled biphasically.

When a murine leukemia L1210-specific Lyt-2+ T cell clone, K7L, was injected i.p. into CD2F1 mice together with L1210, the normal growth of L1210 in the peritoneal cavity of the mice at the early stage (days 0 to 5) was strongly inhibited, but L1210 grew progressively at the middle-stage (days 5 to 10), and then was rejected at the late stage (days 10 to 20). The mice thus survived for long times (more than 60 days), whereas the normal control injected with L1210 alone died within 14 days. The L1210 that grew at the middle stage in mice initially inoculated with L1210 together with K7L was a K7L-insensitive (K7L-) variant. All of eight tumor clones established from L1210-K7L- by limiting dilution was insensitive to the antitumor activity of K7L, and this property of tumor clones was stable after repeated in vitro passage. The initial depression of the L1210 growth by K7L followed by growth and rejection of the variant L1210-K7L- by the host T cell activity was then found to prepare a strong, long-lasting (more than 3 mo) immunity to protect mice against the high-dose (10(7) cells per mouse) challenge of original L1210. Corresponding to this result, definite tumor (L1210)-specific cytotoxic T lymphocyte (CTL) activity against both variant and original L1210 targets was developed by antigen (L1210) restimulation in the culture of spleen cells from these mice, but was not increased to a detectable level before L1210-K7L- variant started to grow. It was suggested that the 1210-K7L- variant and the original L1210 should have the common tumor-specific antigen that was independent of the K7L-reactive antigen, and that original L1210, whose growth was retarded by K7L, primed the host with the common antigen to be enormously boosted by the subsequently growing L1210-K7L- variant.

The murine leukemia L1210-specific cytotoxic T-cell clone K7 was established by repeated antigenic stimulation of spleen cells of L1210-immune CD2F1 mice in long-term culture. K7 possessed L1210-specific cytolytic activity detectable by the 51Cr-release test, but lost its cytolytic activity about 100 days after initiation of culture (designated as clone K7L). Clone K7L retained its L1210-specific tumor-growth-inhibitory activity independently of culture supplementation with IL-2. K7L possessed the cell-surface antigenic phenotype of cytotoxic T cells, Thy-1+, Lyt-1-, Lyt-2+. This clone K7L displayed surprisingly strong activity in specifically inhibiting in vivo tumor growth of L1210 by day 5 in the peritoneal cavity of CD2F1 mice when injected together with 10(5) tumor cells (more than 90% inhibition at E/T = 5), and prolonged survival times of most of the mice for more than 60 days, whereas control mice inoculated with L1210 alone died on day 9-17. This unique in vivo anti-tumor activity was not correlated to the in vitro cytolytic activity. Nevertheless, bystander inhibitory effect on the growth of third-party tumor cells (P388) was not seen in mice injected with a mixture of L1210 and P388 together with K7L, suggesting that K7L inhibited L1210 growth by direct cell-to-cell interaction. Host cells such as X-irradiation (800R)-sensitive lymphocytes and Carrageenan-sensitive macrophages were not involved in the early growth inhibition of L1210 by K7L.

Immunogenicity for T cell-independent B-cell response assessed by splenic plaque-forming cell (PFC) response and cell-surface expression measured by laser flow cytometry of various class I H-2 antigens on mouse red blood cells (RBC) were compared. It was found that the order of magnitude of both immunogenicity and cell-surface expression on RBC is H-2Dd much greater than H-2Db greater than H-2Kd, H-2Kb. Furthermore, H-2d public antigens and H-2Ld antigens were neither immunogenic nor easily demonstrable on RBC. These findings contrasted with poor immunogenicity for PFC response (Nakashima et al. 1982, 1983) and proportionally strong expression of H-2 antigens on lymphoid cells. Immunogenicity and cell-surface expression of H-2Dd antigen on RBC were not shown to be controlled by the action of genes outside H-2D. It was therefore suggested that a number of H-2 antigens, including H-2Kd private, H-2Kb private, and H-2d public specificities are at least functionally defective on RBC. This is possibly due to the structural characteristics of the antigens. Since immunogenicity and cell-surface expression were in parallel, the expression of H-2 antigens on RBC must be dictated by a subset of B cells whose activity was assessed by PFC response. This finding supports the view that the H-2 molecules display a new category of activity which is different from their ability to activate T cells and depends on their expression on RBC.

The afferent arc of the in vivo cytotoxic T-cell immunity assessed by second set rejection of ascitic allogeneic tumors was shown to be depressed by bacterial lipopolysaccharide (LPS) that was administered simultaneously with or 1 day before injection of allogeneic spleen cells as stimulators. Two different LPSs from Escherichia coli O55 and Klebsiella O3 displayed similar activities whereas dextran sulfate, concanavalin A, or poly A:U was not effective. Stimulator activities of allogeneic cells was not directly modified by LPS. Any definite suppressor activity on afferent or efferent arc of the T-cell response was not demonstrable in mice receiving LPS and allogeneic cells. Further, the LPS effect for immune depression was not diminished by whole body X-ray irradiation to the recipient at 300 R, which ablated the B-cell reactivity to LPS for polyclonal activation, or by treatment of the recipient with carrageenan, a known toxic agent to macrophages. It was suggested from these results that LPS suppresses the cytotoxic T-cell immunity by modulating responder T cells to be temporarily refractory to the allogeneic stimulus rather than by activating suppressor cells such as radiation-sensitive lymphocytes and carrageenan-sensitive macrophages.

Syngeneic spleen cells (SPC) sensitized in vitro with noninfectious NVJ were shown to effectively stimulate mice to generate the HVJ-specific cell-mediated immunity for second set rejection (SSR) of virus-infected syngeneic leukemia cells. As few as 10(4) live but not disrupted SPC either infected with a temperature-sensitive mutant of HVJ (HVJts) or sensitized passively with ultraviolet (UV)-inactivated HVJts were active as immunogen. Syngeneic SPC as the carrier of virus could be replaced by allogeneic SPC or L cells, a fibroblast cell line, without reduction of the immunogenicity. Further study demonstrated that a special density of antigen on the surface of HVJts-sensitized SPC is required for high immunogenicity. It was suggested that live cells appropriately sensitized with noninfectious virus would serve as an excellent vaccine for virus-specific cell-mediated immunity.

Early and late primary IgM antibody responses of mice to Thy-1.1 antigens showed different antigenic and cellular requirements. We studied genetic controls of the early primary responses, which could be induced by subcellular thymocyte antigens independently of host T-cell activity. All Thy-1.2 mouse strains of Igha (BALB/c and BC8), Igh-VaCb (BAB14), Ighd (AKR/Cum), Ighj (CBA/J, C3H/HeN, C3H.SW, and C3H.JK), and Ighn (NZB) definitely responded early to Thy-1.1 antigens from AKR/J (Ighd), A.Thy-1.1 (Ighe), or B10.Thy-1.1 (Ighb) mice or SD rats, whereas all strains of Ighb (C57BL/6, C57BL/10, B10.D2, B10.BR, B10.A, CB20 and CWB), Ighc (DBA/2), Ighe (A/J), and Igho (C.AL20) responded poorly to the same antigens. This contrasts with the observation that both strains of Ighj (C3H/HeN) and Ighb (B10.BR) responded well at later times. As was the case for late responses, the matching of H-2 between donor and recipient resulted in early responses of exceptional quality in high-responder strains. It was concluded that under the influence of H-2, whose incompatibility between donor and recipient partially interferes with responses, early but not late primary Thy-1.1-specific antibody responses are selectively controlled by Igh-V or closely linked Ir gene(s) as a new VH marker.