Studies on vasculitis

Summary Human cutaneous vasculitis lesions tend to be chronic in contrast to ephemeral experimental Arthus responses. Human lesions were examined for fixed antiglobulin antibodies, as occur in rheumatoid joint synovia, which could bind globulins to form tissue‐damaging complexes and perpetuate the inflammation. The immunofluorescence procedure was modified by pretreating sections with 5% bovine serum albumin, and by using fluorescein conjugates of F(ab) 2 portions of antibodies to avoid the antigen‐nonspecific binding that sometimes occurs in inflamed or necrotic tissue. Previous findings of immunoglobulins in lesions were confirmed by the more discriminating technique. IgG and IgM was present more frequently in lesions with mainly mononuclear cell changes, than in those with mainly neutrophil changes, leucocytoclastic or necrotizing vasculitis. Fab occurred in some lesions without Fc of IgG or IgM. Three lesions containing IgM or IgM and IgG, specifically bound heat‐aggregated whole IgG or Fc of IgG. None bound IgM. The results indicate that the immunoglobulin in some cutaneous vasculitis lesions is locally formed or fixed antiglobulin, which will bind aggregated IgG possibly forming complexes perpetuating the lesion.