Immunologic response to A and B erythrocytic antigen.

Immunologic response to A and B erythrocytic antigen stimulation was studied in patients with pemphigus, in patients with systemic lupus erythematosus (SLE), and in normal subjects. Patients with pemphigus and normal subjects demonstrated a similar specific response (isohemagglutinins). A comparison between patients with pemphigus and SLE showed higher titers in the latter. Intercellular antibody titers increased after stimulation; corresponding titers were unaffected by isohemagglutinin absorption. Direct immunofluorescent studies showed IgG deposits in the intercellular spaces of the skin of the patients with pemphigus. However, C3 was found in the same sites in only three cases of pemphigus erythematosus. Immunofluorescent studies for IgG at the basal membrane were positive in only two cases of pemphigus erythematosus. Immunologic response of patients with pemphigus was similar to that of controls; however, it differed from that of patients with SLE.