Cutting Edge: γδ T Cells Provide Help to B Cells with Altered Clonotypes and Are Capable of Inducing Ig Gene Hypermutation

Abstract

It has not been resolved whether γδ T cells can collaborate with germinal center B cells and support Ig hypermutation during an Ab response to a truly defined T-dependent Ag. In this study, we show that in the absence of αβ T cells, immunization with the well-defined T-dependent Ag, (4-hydroxy-3-nitrophenyl) acetyl (NP) conjugate, was able to induce Ig hypermutation. However, the clonotypes of B cells responding to NP were dramatically altered in TCR β^−/− mice. Unlike B cells in wild-type mice that use canonical VDJ rearrangements, most NP-responding B cells in mutant mice use analog genes of the J558 gene family. In addition, the majority of anti-NP Abs produced in mutant mice use κL chain instead of λ1L chain, which dominates in mice of Igh^b background. Thus, the B cell population that collaborates with γδ T cells is distinct from B cells interacting with conventional αβ Th cells.