CD5–NK1.1+ γδ T cells that develop in a Bcl11b-independent manner participate in early protection against infection

Among the innate-like γδ T cells in the fetal thymus committed to forming IFN-γ-producing effector cells, those programmed to develop at the earlier DN2-stage in a Bcl11b-independent manner seem to be more primitive T cells of the innate immune system. The ontogenetic wave of γδ T cell development in the thymus suggests that Bcl11b-independent γδ T cells play a critical role in protecting against infections at the earlier stages after infection. To test this hypothesis, we characterized the innate-like γδ T cells that developed from the DN2a-stage in a Bcl11b-independent manner using Bcl11b conditionally deleted mice, in which T cell development is completely blocked before the DP stage. Conclusion: Bcl11b-independent γδ T cells had a CD5– NK1.1+ Granzyme+ phenotype and were abundant in the liver in WT mice. Bcl11b-independent γδ T cells contributed to early protection against L. monocytogenes infection. Bcl11b-independent γδ T cells participate in early protection as “primitive innate-like γδ T cells” in host defense.