REGULATION OF MACROPHAGE ACTIVATION MARKERS BY IL-4 AND IFN-GAMMA IS SUBPOPULATION-SPECIFIC

We have addressed the differential regulatory properties that IFN-γ and IL-4 exert on macrophage (Mφ) subpopulations. For this purpose, Thyoglicolate-, Peptone-, and Con A-elicited Mφ, as well as bone marrow-derived Mφ and P388D1 cells, were cultured in the presence of either IFN-γ or IL-4. The expression of LFA-I, Mac-1, and Mac-2 after this treatment was studied by FACS analysis. We have found that these surface molecules are differentially modulated by the two lymphokines, depending on the Mφ subpopulation studied. Mac- I is upregulated only in Thyoglicolate-elicited cells after treatment with IFN-γ, while no change in the expression of Mac-2 was observed in any of the groups. LFA-I is upregulated by IFN-γ in Thyoglicolate- and bone marrow-derived Mφ and P388D1 cells, while IL-4 does not induce LFA-1 on these cells. Interestingly, however, we have observed the reverse situation on Con A-elicited Mφ, where a strong induction of LFA-1 is achieved by treatment of the cells with IL-4, while IFN-γ does not modify the expression of this antigen. Our results obtained with the lymphokine-stimulated Mφ are interpreted in the context of functionally induced Mφ subpopulations, which might be regulated by either Th1 or Th2 CD4+ T cells. Thyoglicolate-elicited Mφ may represent the in vitro equivalent of a Mφ subpopulation regulated in vivo by Th1 cells while Con A-elicited Mφ could be the equivalent of a subpopulation regulated by Th2 cells. © 1991.