Different large deletions of t cell receptor vβ genes in natural populations of mice*

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Abstract
A panel of geographically separate Mus m. domesticus and Swiss mice from several sources was screened for deletions in the T cell receptor variable (V) β locus. Four out of forty-three strains tested show a deletion identical to or larger than the deletion previously described in SJL mice. To our knowledge, this is the first time that such important Vβ deletions are described in inbred or partially inbred wild-derived strains of mice. On the other hand there seems to be very little polymorphism between the remaining Vβ genes. Expression of Vβ genes in peripheral and intra-thymic T cells was tested using antibodies specific for different Vβ polypeptide chains. Flow cytometry analysis revealed a high expression of Vβ6 and Vβ17 genes in the Copacabana Swiss-derived strain and an absence of Vβ17 expression in the WLA wild-derived strain. The three Mus m. domesticus strains (WLA, DDO and WBG) having deleted two to three additional Vβ subfamilies compared to SJL present no apparent immune deficiencies or autoimmune disorders. We conclude that relatively few Vβ genes may suffice for unimpaired survival of wild mice and that there is a selective pressure for the structural conservation of the remaining Vβ genes.