Granuloma annulare. Identification of cells in the cutaneous infiltrate by immunoperoxidase techniques.

To characterize the immunopathologic process of granuloma annulare, frozen sections of eight specimens were evaluated with monoclonal antibodies directed against T lymphocytes and the monocyte-macrophage series, in conjunction with immunoperoxidase techniques and with histochemical staining. The predominant lymphocyte was an activated T lymphocyte (Leu 1+, HLA-Dr+) with an excess of helper-inducer phenotype (Leu 3a+), as compared with suppressor-cytotoxic phenotype (Leu 2a+). OKT-6+ Langerhans' cells were observed in the epidermis, and numerous OKT-6+ cells were observed in the perivascular and granulomatous infiltrate. The use of four monoclonal antibodies, having specificity against peripheral blood monocyte antigens, revealed three different staining patterns in the granulomas. Finally, mast cells were present in perivascular and granulomatous infiltrates. Our results demonstrate that the cutaneous infiltrate of granuloma annulare contains all of the principal cell types that characterize cell-mediated immune responses.