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 (Mø) supernatants. Both inhibiting and enhancing activities were identified in normal and TBH Mø supernatants. The present data suggest that TBH Mø supernatants contained more inhibitory activity than normal host Mø supernatants and that enhancing activity of Mø 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 Mø as being partially responsible for the immune dysfunction seen in TBH, and extends previous findings on the ability of Mø to regulate the immune response in an attempt to achieve homeostasis.