Differences in marker expression among branched histiocytic cells in T-cell areas of the lymphoreticular system and among their epidermis- and mucosa-associated equivalents

Summary Branched histiocytic cells of the epidermis, the oral and anal mucosa, the tonsillar crypt epithelium, the thymus and of the T-cell-dependent areas of lymph node, spleen, and tonsil were examined with immunohistochemical single- and double-staining techniques. The markers used were a monoclonal anti-T6-antibody, a monoclonal anti-HLA-DR-antibody, heteroantiserum to S-100 protein and peanut agglutinin. Anti-HLA-DR and peanut agglutinin reacted with a considerable number of branched histiocytic cells, whereas anti-T6 and anti-S-100 protein only stained relatively small subpopulations. Concerning the population of branched histiocytic cells, double-staining revealed that the tissue distributions of all the markers used overlapped each other to various degrees; this was demonstrated by the different numbers of double-stained cells obtained in the experiments using all six possible combinations of primary reagents. The number of branched histiocytic cells co-expressing the markers varied depending upon marker combinations, types of tissue and microenvironment. We suggest that much of the immunologic phenotype of branched histiocytic cells is dynamic rather than static.Abbreviations used BHCs branched histiocytic cells - anti-T6 monoclonal antibody to T6 antigen - anti-HLA-DR monoclonal antibody to HLA-DR - anti-S-100p antiserum to S-100 protein - (anti-)PNA (anti-)peanut agglutinin - GAM goat anti-mouse IgG - RAM rabbit anti-mouse IgG - GAR-AP alkaline phosphatase-conjugated goat anti-rabbit Ig - SAR porcine anti-rabbit Ig - PAP peroxidase-anti-peroxidase complex - APAAP alkaline phosphataseanti-alkaline phosphatase complex - iAP indirect alkaline phosphatase - AEC 3-amino-9-ethylcarbazole - FB fast blue BB salt - levamisole L-]2,3,5,6-tetrahydro-6-phenylimidazo2,1-b]thiazole - DMF NN-dimethylformamide - PBS phosphate-buffered saline solution - + positive reaction of a cell with a resp. marker - – negative reaction of a cell with a resp. marker This work was supported by the German Research Foundation (DFG: Mo.384/1-2)