Abstract
Macrophage (M phi) phenotype and function can be modulated by various T-cell lymphokines (LK). The alteration of M phi phenotype is a result of LK concentration, duration of exposure, and the level of M phi activation when obtained from in vivo sources through elicitation by either sterile irritants or cellular immune mechanisms. To dissect M phi activation into discrete signals, we constructed T-cell hybridomas by fusing hypoxanthine-aminopterin-thymidine-sensitive BW5147 cells with nylon wool-purified, concanavalin A-stimulated T cells. The resulting T-cell hybrids were screened for their ability to (i) protect M phi from the cytopathic effect of Naegleria lysates, (ii) induce class II major histocompatibility complex gene product (Ia antigen) expression, (iii) increase tumoricidal and cytostatic activity, and (iv) alter ectoenzyme profiles on either resident or thioglycolate-elicited M phi. Two hybridomas (T-3 and T-9) were selected for further evaluation because of their activity patterns. Supernatants from T-3 and T-9 were compared with cloned gamma-interferon (IFN-gamma) for alterations of biological activities. Both T-3 and T-9 were able to protect resident-M phi cells from Naegleria lysate but had no protective effect on thioglycolate-induced M phi. T-9 supernatant had patterns of activity similar to IFN-gamma, whereas T-3 patterns were different. The addition of anti- IFN-gamma removed T-9 cytostatic activity while not affecting T-3-induced activity. The LK inducing protection from the cytopathic effect of Naegleria lysate is not IFN-gamma but another molecular moiety. We conclude that the activation of M phi for the destruction of tumor cells and amoebae may occur via different mechanisms.