Autologous mixed lymphocyte reaction and T-cell suppressor activity in patients with Henoch-Schönlein purpura and IgA nephropathy.

To assess the existence of persistent abnormalities in the cellular mechanisms regulating the immunoglobulin (Ig) synthesis in Henoch-Schönlein purpura (HSP) and IgA nephropathy, we studied through a hemolytic plaque assay (PFC) the response to the autologous mixed lymphocyte reaction (AMLR) and the T-cell suppressor activity in 24 patients with IgA nephropathy, in 20 individuals with inactive HSP (IHSP) and in 18 normal controls. In the group with IgA nephropathy there was a significant increase in the number of IgA-secreting cells after AMLR (p less than 0.01), and 9 of the 15 patients tested had an impaired generation of T-cell suppressor activity. No such abnormalities were found in individuals with IHSP. These findings support the existence of persistent defect in the mechanisms regulating the Ig synthesis, limited only to the patients with IgA nephropathy.