An increase in peripheral blood Ia-positive T cells in Sjögren's syndrome correlates with a decrease in the autologous mixed lymphocyte response.
The defective autologous MLR was studied in Sjögren's syndrome (SS) in relation to Ia+ cells as determined by reactivity with a monoclonal anti-human Ia antibody. By indirect immunofluorescence, the percentage of Ia+ T lymphocytes was increased in nine of 15 patients. There was no correlation with clinical features or drugs. The percentage of Ia+ T cells in the non-T cell preparations was normal. An inverse correlation was found between the percentage of Ia+ T cells and the proliferative response to autologous non-T cells. Removal of Ia+ T cells enhanced both the autologous MLR and the allogeneic MLR. Thus Ia+ T cells contain suppressor cells in the MLR, but this may not be the sole explanation for the defective autologous MLR.