Immunohistochemical studies of major histocompatibility antigens in a case of the bare lymphocyte syndrome without immunodeficiency.

A case of the bare lymphocyte syndrome without apparent immunodeficiency was observed. The patient had, in addition, ichthyosis vulgaris and sinobronchial disease. A pustular lesion developed at first on the anterior aspect of lower part of the left leg. This lesion gradually increased in size and evolved into giant indurated, irregular adjoining plaques. On biopsy, the histologic findings were similar to necrobiosis lipoidica. No human lymphocyte antigen (HLA) class I antigens were detected on peripheral mononuclear cells; however, HLA-DR antigens were present on B lymphocytes. Immunohistochemical studies disclosed defective expression of class I antigens in the non-lesional skin, but positive expression was demonstrated in the lesional area. HLA-DR antigens were expressed on keratinocytes and on most infiltrating inflammatory cells in the affected skin. It is therefore speculated that class I antigen appearance and mononuclear cell infiltrate each induces the other and that together they play an important role in the formation and enlargement of the skin lesion.