Vδ2 T-lymphocyte responses in cord blood samples from Italy and Cote d'Ivoire

Cord blood T lymphocytes are immature and their functional defect partially reflects a suboptimal level of costimulatory signals provided by neonatal antigen-presenting cells. Neonatal V delta 2 T lymphocytes, a small component of cellular immunity involved in the response against bacteria, protozoa, virus-infected cells and tumours, are also considered to be immature. Cord blood V delta 2 T lymphocytes are mostly naive, proliferate poorly and do not produce cytokines in response to the model phosphoantigen isopentenyl pyrophosphate. We cultured cord blood mononuclear cells with the aminobisphosphonate Pamidronate or with live bacille Calmette-Guerin, and showed that both elicit a strong cord blood V delta 2 T-cell proliferative response, inducing the expression of activation markers and promoting the differentiation from naive to memory cells. Our results suggest that cord blood V delta 2 T cells are not inherently unresponsive and can mount strong responses to aminobisphosphonates and mycobacteria. Neonatal V delta 2 T lymphocytes may be important participants in responses to microbial infections early in life.