FUNCTIONALLY DISTINCT SUBSETS OF HUMAN GAMMA-DELTA-T-CELLS

To determine if effector subsets exist among human gamma/delta T cells, we examined the cytokine production and cytotoxic activity of gamma/delta T cells clones with different accessory molecule phenotypes, V-delta and V-gamma gene expression, and J-gamma rearrangements. T cell clones bearing gamma/delta T cell receptor produce an array of cytokines like alpha/beta T cell clones. Individual gamma/delta T cells clones produced a characteristic array of cytokines without correlation with V-delta or V-gamma gene expression. However, when phenotypic subsets were considered, CD4+ gamma/delta clones produced significantly higher levels of interleukin 2 and granulocyte-monocyte colony-stimulating factor compared with CD4-CD8- and CD8+ gamma/delta clones. Similarly, when cytotoxic potential was assessed, CD4+ gamma/delta clones exhibited minimal activity when compared with CD4-CD8- and CD8+ adult peripheral blood gamma/delta clones. We conclude that functionally distinct gamma/delta T cell subsets exist and suggest that these subsets may correlate with expression of the CD4 accessory molecule.