CD5-NK1.1+ γδ T Cells that Develop in a Bcl11b-Independent Manner Participate in Early Protection against Infection.

We recently found that a unique subset of innate-like γδ T cells develops from the DN2a stage of the fetal thymus independently of the zinc-finger transcription factor B cell leukemia/lymphoma 11b (Bcl11b). Herein, we characterize these Bcl11b-independent γδ T cells in the periphery as CD5-NK1.1+ and Granzyme B+, and we show that they are capable of producing interferon (IFN)-γ upon T cell receptor stimulation without Ca2+ influx. In wild-type mice, these cells were sparse in lymphoid tissues but abundant in non-lymphoid tissues, such as the liver. Bcl11b-independent CD5-NK1.1+ γδ T cells appeared and contributed to early protection before Bcl11b-dependent CD5+NK1.1- γδ T cells following Listeria monocytogenes infection, resembling their sequential appearance during development in the thymus.