Expression of antibody V-regions is genetically and developmentally controlled and modulated by the B lymphocyte environment.

In this study we performed a comprehensive analysis of VH family usage in the emergent, available and actual repertoires of neonatal and adult BALB/c and C57BL/6 (B6) mouse strains. For this purpose we used an in situ hybridization technique that allows the detection of VH-gene expression at a single cell level. We have found that VH gene expression in neonatal mice is determined by a non-random position-dependent process which favours the utilization of the most D-proximal VH 7183 family. The preferential usage of the 7183 family is also characteristic of early differentiating bone marrow B cells of adult BALB/c mice. At different stages of ontogeny and B cell development VH family repertoires evolve in a strain-specific manner, with significantly higher utilization of the VH J558 family in B6 mice. In the peripheral immunocompetent cell pool, local environmental factors can further modulate VH family expression and lead to increased representation of the VH J558 family in peripheral lymph nodes and of the VH X-24 family in intestinal Peyer's patches. In conclusion, our present results indicate that VH family usage is controlled by genetic, developmental and environmental factors and suggest that selection of antibody repertoires can occur at multiple stages in B cell development.