Mononuclear cell subset-specific monoclonal antibodies, indirect immunoperoxidase labeling, and a specific quantification technique were used to determine the constitution of mononuclear cell infiltrates associated with bullous pemphigoid (BP), pemphigus vulgaris (PV), dermatitis herpetiformis (DH), and linear IgA bullous disease, as well as those in normal skin (NS) from healthy adult volunteers. Bullous pemphigoid and PV lesions contain significantly greater numbers of T lymphocytes (p < 0.001), including both T helper/inducer and T cytotoxic/suppressor subsets, macrophages (p < 0.002), and Langerhans cells (p < 0.01), than NS or lesions of DH, supporting the concept that cell-mediated immunity is involved in bulla formation and autoantigen presentation in BP and PV. The infiltrates associated with DH lesions appear to reflect a different mechanism of autoantibody production and bulla formation.