Requirement for CD4+ T cells in the gammadelta T cell proliferative response to Daudi Burkitt's lymphoma

Daudi Burkitt's lymphoma cells stimulate the proliferation of Vgamma2 Vdelta2 T cells in human peripheral blood mononuclear cells (PBMC). Transfection studies have established that the gammadelta T cell receptor is sufficient for recognition of a ligand associated with Daudi cells. Since other studies have demonstrated the need for cooperation between alphabeta T cells and Vgamma2 Vdelta2 T cells in the proliferative response to mycobacterial antigens, we used human, unfractionated PBMC and PBMC depleted of specific T cell subsets to determine whether the gammadelta T cell response to Daudi cells also requires cooperation between alphabeta and gammadelta T cells. In the current study, we demonstrate that depletion of CD4+ T cells substantially reduces the overall proliferative response of PBMC to Daudi cells and subsequent gammadelta T cell expansion. IL-2 production by PBMC in response to Daudi cells was also decreased by depletion of CD4+ T cells, but not by depletion of CD8+ or gammadelta T cells. In the CD4+ T-cell-depleted PBMC, proliferation in response to Daudi cells was restored by the addition of IL-2. These data stress the importance of cooperation between alphabeta and gammadelta T cells in the response to some complex antigens.