Localization of spontaneously hyperactive B cells of NZB mice to a specific B cell subset

NZB mice produce numerous autoantibodies and have a subpopulation of B cells characterized by marked spontaneous hypersecretion of IgM. The latter trait is determined by autosomal genes in F₁ hybrids of NZB and normal strains. We tested the hypothesis that the hypersecreting B cells of NZB mice are contained within a specific subpopulation by examining (CBA/N x NZB)F₁ hybrids. CBA/N mice have an X-linked recessive defect that results in the absence of a functionally distinct B cell subpopulation and impaired antibody responses. The hyperactivity of B cells, characteristic of the NZB parent, was transimitted to the F₁ female, but was not expressed by the F₁ male, which manifested the CBA/N B cell hyporesponsiveness. By contrast, the NZB xenotropic virus was expressed equally by both male and female F₁ mice. We conclude that the NZB B cell abnormality resides within the B cell subpopulation affected by the CBA/N mutation.