Antibody-mediated rosette formation of epidermal cells with leukocytes in pemphigus vulgaris.

Human peripheral-blood leukocytes (PBLs) were found to form rosettes with cultured human epidermal cells or a mouse epidermal cell line (Pam cells), but not with fibroblasts, when preincubated with heat-inactivated sera from patients with pemphigus vulgaris. Increased rosette formation was observed, however, when untreated sera were used for passive sensitization. Complement was not required for this reaction, because purified IgG fractions from a protein-A/Sepharose column retained the ability to induce rosette formation. Blocking experiments with alpha-methyl-mannoside suggested that a carbohydrate moiety is involved in the binding of sensitized cells to epidermal cells. Thus, human PBLs can adhere to cultured mouse epidermal cells in the presence of PV IgG antibodies.