Differentiation of the effects of preincubation and indomethacin on lymphocyte transformation

Abstract

Lymphocyte-transformation responses of human peripheral blood mononuclear cells to a suboptimal concentration of phytohemagglutinin were found to be augmented by either 24-hr preincubation or by the addition of 1.0 μg/ml of indomethacin to the cultures. Preincubation altered the lymphocyte-transformation kinetics by accelerating the response in a manner similar to that obtained by increasing the concentration of mitogen. Indomethacin did not cause this type of effect, but did produce a fairly constant degree of enhancement throughout the period of maximal response (cultures harvested on Days 3 to 7). Indomethacin also produced enhancement of the lymphocyte transformation response to the suboptimal phytohemagglutinin concentration even when the lymphocytes were preincubated beforehand, indicating that these two maneuvers were additive. Fresh, autologous, mononuclear cells did not suppress the enhanced response of preincubated cells, indicating that, in this system, preincubation may involve changes in the responding cells themselves rather than destruction of a suppressor-cell population. Therefore, these studies indicate that a short (24-hr) preincubation and the addition of indomethacin (1.0 μg/ml) to lymphocyte cultures produce enhancement of the lymphocyte-transformation response to a suboptimal mitogen concentration through different mechanisms.