In vitro effects of adenosine induced supernatants on human T lymphocyte functions

Theophylline-resistant T lymphocytes (T-res), enriched in T4+ cells, can be differentiated toward a regulatory activity in adenosine. This work describes the in vitro effects of the supernatant (SnA) generated from adenosine (0.1 mM) treated T-res cells on (i) the proliferative response of lymphocytes to mitogenic or allogeneic stimuli, and (ii) on the expression of Interleukin 2 (IL2) receptors (Tac). SnA showed an inhibitory effect to the mitogenic response of autologous resting lymphocytes. By contrast, preactivated lymphocytes appeared to be enhanced in their blastogenic response both to polyclonal activators and to alloantigens by the addition of SnA. SnA, if added simultaneously with a mitogen to resting lymphocytes, did not exert any effect on the I12 receptor expression; if added to preactivated lymphocytes, it induced an important increase in the number of Tac positive cells. Furthermore, the addition of SnA to activated T cells in mixed lymphocyte reactions (MLR) enhanced the proliferation of allospecific T lymphocytes with displayed regulatory activity when added to third party MLR. SnA seems to enhance an allogeneic driven suppressor activity, mainly affecting the early steps in lymphocyte activation.