Interleukin-2 and neopterin-induced neopterin release from peripheral blood mononuclear cells

Stimulation of peripheral blood mononuclear cells (PBMC) by the mitogenic lectins, phytohaemagglutinin (PHA) and concanavalin A (conA), the lymphokine gamma-interferon (gamma-IFN) and interleukin-2 (IL-2) and the pterin neopterin, caused an increased release of neopterin from those cells, with peak levels after 7 days of stimulation. In contrast to gamma-IFN, IL-2 and neopterin failed to induce neopterin release from purified macrophages. IL-2- and neopterin-induced release of neopterin from PBMC is not dependent on proliferation and is partially inhibited by the addition of anti gamma-IFN or anti IL-2 receptor. Neopterin autoinductive production can explain the amplificated neopterin release during activation of the cellular-mediated immune response (CMI), in spite of the decrease in the T helper cell subsets, which are the main gamma-IFN producers.