Alternative induction of IFN-alpha and IFN-gamma by Listeria monocytogenes in human peripheral blood mononuclear leukocyte cultures

Abstract

Production of interferon (IFN) by Listeria monocytogenes (LM) in human peripheral blood mononuclear leukocyte (PBML) cultures was studied. Acid-labile IFN-gamma was produced in Ficoll-Hypaque-purified mononuclear cell cultures in response to heat-killed LM (HK-LM). However, plastic dish (PD)-nonadherent cells produced acid-stable IFN-alpha, whereas the cells reconstituted with PD-adherent cells (M phi) and PD-nonadherent cells produced IFN-gamma by HK-LM, IFN-gamma was produced only in a mixture of SRBC rosette-forming (T) cells and M phi. Neither T cells nor M phi produced IFN by HK-LM. On the other hand, IFN-alpha was produced from non-T and nylon wool-nonadherent (non-T, non-B) cells by stimulation with HK-LM in the absence of M phi. A reciprocal type of IFN produced in human PBML was absolutely dependent on the presence or absence of M phi. A soluble fraction extracted from sonically disrupted LM had a high potential to induce IFN-gamma in human PBML. Possible mechanism of the alternative production of IFN-gamma or IFN-alpha in human PBML by Listeria are discussed.