Repertoire selection and effector functions of neonatal γδ T cells (85.12)

Abstract

Abstract The neonatal T cell repertoire includes a low frequency of Vγ2Vδ2 T cells. This population is poorly reactive to phosphoantigens or aminobisphosphonates, compared to the adult repertoire in blood. The neonatal Vδ2 cell population also shows a reduced proportion of Vγ2-Jγ1.2 rearrangements; this TCR chain combines with the Vδ2 to endow phosphoantigen responsiveness. We are interested in how the neonatal repertoire is selected to produce the dominant Vγ2-Jγ1.2 rearrangement seen in adults. IL-15 did not improve responses to stimulation, but improved survival. Both IL-2 and IL-15 up-regulated NK receptors and perforin production, although IL-2 preferentially down-regulated CD27 expression, that may be linked to the development of cytotoxicity. Curiously, aminobisphosphonate stimulation in a single round selected a Vγ2 repertoire similar to adults. Thus, neonatal γδ T cells found in cord blood are an attractive model for understanding the genesis of cytotoxic T cells lineages.