Immunohistochemical study on antigenic phenotype of Langerhans cell histiocytosis.

Immunohistochemical study on 26 cases of Langerhans cell histiocytosis (LCH) using several leukocyte antibodies in addition to traditionally used markers (S-100 protein and peanut agglutinin) revealed that the proliferating cells of LCH expressed UCHL1, MT1 as well as classically known positivity for S-100 protein, HLA-DR and peanut agglutinin but were negative for OPD4. In comparison to S-100 protein peanut agglutinin (PNA) using a two stage method produced weaker staining and positively stained cells were sparse. Also in this study, a small proportion of proliferating cells in LCH was observed to be reactive for both myeloid/macrophage antigens (KPI, MAC 387 and lysozyme) and Langerhans cell marker (S-100 protein), verifying the existence of a hybrid form of histiocytes.