Identification of T-cell subpopulations in granuloma annulare

Granuloma annulare is a lymphohistiocytic process of unknown cause characterized by necrobiotic dermal papules. Acetone-fixed frozen sections of eight granuloma annulare lesions were studied for the presence of T-cell subsets, using monoclonal antibodies to T-cell surface antigens. The palisading and perivascular lymphocytic infiltrate shows that most of the mononuclear cells are reactive with LEU-1 antibody, which characterizes peripheral T cells and activated T cells. Numerous cells were reactive with LEU-3a antibody, which identifies the helper-inducer T-cell subset. Some cells were positive with LEU-2a antibody, which detects suppressor-cytotoxic cell populations. Masses of histiocytes were identified infiltrating between the collagen fibers and surrounding the central necrobiosis area; the histiocytes showed a very strong diffuse acid phosphatase and nonspecific esterase activity. These findings suggest that a cell-mediated immune response may be the dominant pathogenic event in granuloma annulare.