金子 千之

Langerhans cells (LCs) and interdigitating cells (IDCs) are said to have the same morphological and immunological characteristics. We have reported on Birbeck granules (BG)-bearing LCs, which are positive for both OKT-6 (CD1a) and anti S-100 protein antibodies, and IDCs which are only positive for S-100 protein, but negative for OKT-6. In this paper, we examined the characteristics of dendritic cells in dermatopathic lymphadenopathy (DPL) and Histiocytosis X (HCX) using immunohistochemical and immuno-electron microscopic techniques. The majority of the dendritic cells which existed in the lymph nodes of DPL were positive for OKT-6. We concluded that these dendritic cells were not IDCs, but LCs. Electron microscopically, LCs in these lymph nodes contained only a few BG. Most of the LCs were negative for PCNA antibody. This finding means that the proliferative activity of these LCs is very low and that they do not divide or proliferate in the lymph nodes. On the other hand, HCX is considered to be a rare proliferative disorder of LCs. HCX cells were positive for S-100, OKT-6, CD4 (Leu3a) and HLA-DR (Ia), in addition they were highly positivity for PCNA. These findings indicate that HCX cells originate in immature cells which are already part of the Langerhans cell lineage.