Con A suppressor cell assay: a further characterization.

Con A induced suppressor cell assay was further characterized in this study. Significant lower mitogenic responses of autologous fresh cells cocultured with Con A-activated cells were found when compared with the response of cocultures of responders plus control cells preincubated in medium alone. However, Con A-activated cells did not express a real suppression, since no difference was found between responses of fresh responders alone and responses of cocultures with Con A-activated cells. So, Con A activation seemed to block the expression of the enhancement provided by control cells to autologous responders, rather than to induce a real suppressor activity. The induction of the Con A suppressor cell activity required cell proliferation but it was not proportional to the degree of DNA synthesis. Monocyte depleted cell populations exhibited lower Con A suppressor cell activity compared to unfractionated cells, suggesting a cooperative role of monocytes in the Con A induction step. The expression of this activity was not due to a cytotoxicity against the responders and was dependent on the number of activated cells added. Mononuclear cells from active lupus erythematosus (SLE) patients, but not from inactive SLE patients differed from normal controls in showing a significant loss of suppression index.