INFLUENCE OF ST-789 ON INTERLEUKIN-1, INTERLEUKIN-2 AND INTERFERON-GAMMA PRODUCTION FROM NORMAL HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS

ST 789, previously named PCF 39, is a synthetic hypoxanthine derivative endowed with immunomodulating properties. However, the mode of action of this compound on immunocompetent cells has not yet been elucidated and, in particular, no evidence has been provided on its ability to trigger monokine (MK) and lymphokine (LK) release. In this framework, here we have evaluated the influence of ST 789 on interleukin (IL)-1, IL-2 and interferon (IFN)-gamma production from normal human peripheral blood mononuclear cells (PBMC). Results will show that following stimulation of PBMC with lipopolysaccharides (LPS) or lectins [phytohemoagglutinin (PHA) and concavalin A (Con A)] in the presence of increasing concentrations of ST 789 no modification of cytokine release is obtained, in comparison with cultures activated with LPS or lectins. In addition, this hypoxanthine is not able per se to induce release of MKs and LKs. The overall results suggest that ST 789 acts on the immune system through mechanisms which are not dependent on the release of ILs and IFN-gamma.