Immunological abnormalities in psoriatic arthropathy.

Immunological parameters were studied in 25 cases of psoriatic arthropathy. We found in the peripheral blood an increase of IgA, a decrease of IgM, and low conentrations of immune complexes. Anti-gammaglobulin factors, mainly of the IgG class, were detected by indirect immunofluorescence in 55.5% of cases. The study of lymphocyte membrane markers showed a decrease of T cells as investigated by E and "active" E-rosettes, a decrease of EA gamma-rosette-forming cells, and an increase of "high avidity" EA-rosettes. Lymphocyte responses to phytomitogens were normal. There was no correlation between the clinical data and the immunolgical features.