INTERFERON-GAMMA PLAYS A KEY ROLE IN THE HUMAN MIXED LYMPHOCYTE CULTURE

Measurement of cytokines in the mixed lymphocyte culture (MLC) is thou ght to be a new and relevant parameter for bone marrow transplantation (BMT). Our experiments showed that IFN-gamma plays a central role in the cytokine network following alloantigenic recognition, IFN-gamma it self is induced by IL-2 since anti-IL-2 strongly reduced the secretion of IFN-gamma, As anti-IFN-gamma also diminished the response of IL-2 and sIL-2R, a feedback mechanism between these two cytokines is assume d, Addition of rIFN-gamma to the MLC augmented the release of sCD8 mol ecules, whereas sCD4 molecules were reduced, indicating that IFN-gamma led to T cell differentiation instead of IL-2 dependent proliferation , In the MLC, a feedback mechanism between TNF-alpha and IFN-gamma exi sts, since anti-TNF-alpha reduced the secretion of IFN-gamma and anti- IFN-gamma inhibited the release of TNF-alpha. Therefore, IFN-gamma pla ys a critical role in monocyte activation, T cell differentiation, and IL-2-induced cell growth, We conclude that measurement of IFN-gamma m ight be a new and more sensitive parameter for BMT than the establishe d proliferation assay, since IFN-gamma directly quantifies T cell acti vation.