HLA-DR antigens in epithelioid cell granulomas of sarcoidosis, using semithin frozen sections. A concept about granuloma formation.

Mediastinal lymph nodes of 11 patients with Sarcoidosis were studied. The immunoperoxidase technique using monoclonal antibody to HLA-DR antigen revealed on conventional frozen sections epithelioid cell granulomas with intense staining. Localization of this HLA-DR + material on or in cells in these granulomas was possible with 1 mu semithin frozen sections. Epithelioid cells as well as multi nuclear giant cells were seen in these sections with membrane bound HLA-DR antigens. Some problems about HLA-DR antigens in relation with antigen handling, the presence on epithelioid, (and) giant cells and granuloma formation will be discussed.