Human γδ T cells induce dendritic cell maturation

gammadelta T cells are known to be involved in the innate immune defenses against infectious microorganisms. Herein, we considered that gammadelta T cells could also influence adaptative immunity by interacting with dendritic cells (DC) in the early phase of the immune response. To investigate this hypothesis, gammadelta T cells isolated from the peripheral blood of healthy volunteers were cocultured with autologous monocyte-derived dendritic cells, which were subsequently analyzed for their expression of key surface molecules and for their production of IL-12. First, we found that gammadelta T cells induced the upregulation of HLA-DR, CD86, and CD83 on DC. This effect did not require cell to cell contact and could be blocked by a neutralizing anti-TNF antibody. We then observed that gammadeltaT cells activated by the synthetic phosphoantigen bromohydrin pyrophosphate (BrHPP) induced the production of IL-12 (p40) and IL-12 (p70) by DC, an effect that involved IFN-gamma production. The relevance of this finding to DC function was demonstrated by the increased production of IFN-gamma by alloreactive T cells when stimulated in a mixed leucocyte reaction with DC preincubated with activated gammadelta T cells. We conclude that gammadelta T cell activation might result in DC maturation and thereby in enhanced alphabeta T cell responses. (C) 2002 Eisevier Science (USA).