Normal and tumor-bearing host macrophage factor-mediated modulation of mixed-lymphocyte reaction responsiveness: separation of T-lymphocyte subset susceptibility to enhancing and inhibitory factors.

The mixed-lymphocyte reaction reactivity of normal and tumor-bearing host (TBH) T-cell subsets was examined in response to normal and TBH macrophage (M phi) supernatants. Both inhibiting and enhancing activities were identified in normal and TBH M phi supernatants. The present data suggest that TBH M phi supernatants contained more inhibitory activity than normal host M phi supernatants and that enhancing activity of M phi supernatants was restricted to the Lyt 2,3+ population of cells. TBH Lyt 2,3+ cells were more responsive to the enhancing molecule(s) than their normal counterparts. These data were consistent with studies which implicate M phi as being partially responsible for the immune dysfunction seen in TBH, and extends previous findings on the ability of M phi to regulate the immune response in an attempt to achieve homeostasis.