Stimulation of distinct T cell subsets in MLR using human macrophage hybridomas differentially expressing class II...

Recognition of class II antigens by alloreactive T cells is thought to be the major mechanism by which tissues undergo rejection. However, the specific role of the various class II antigens in the stimulation of these alloreactive cells remains to be elucidated. We have recently generated a series of human monocyte hybridomas that express distinct patterns of class II antigen expression. HLA-DR+ as well as HLA-DR-DP+DQ+ hybrids were capable of promoting T cell proliferation in a unidirectional mixed lymphocyte reaction. T cells stimulated by the HLA-DR+ clone 16.1 were predominantly of the CD4 (helper/inducer) phenotype. In contrast, T cells stimulated by the HLA-DR-DP+DQ+ clone 13 appear to reside in the CD8+ T cell subpopulation. Functional assessment of the T cell blasts generated in these cultures demonstrated a predominant helper T cell effect by those T cells stimulated by the HLA-DR+ clone 16.1, while suppressor cell activity was exhibited by T cells stimulated with the HLA-DR-DP+DQ+ clone 13. These data suggest that there may be a differential role for distinct class II molecules in the stimulation of T cell subpopulations.