Increased Con-A-induced thymocyte proliferation and de novo Qa-2 antigen expression in Qa-2-depleted thymocyte cultures.

We have recently shown that thymocyte activation is associated with a strong increase of Qa-2 antigen expression. Contrary to what could be predicted from these results, the initial depletion of Qa-2+ cells from PNA- thymocytes increases the Con-A-induced proliferation. Qa-2+ cells not only reappeared after activation, but were enhanced in Qa-2-depleted PNA- cells compared to the control. The newly formed Qa-2+ population contained a higher percentage of Lyt 1+2- cells and thus seems to be different from the Qa-2+ pool initially present.