Restriction fragment length polymorphism analysis of the V_X locus in human lupus

To evaluate the degree of genetic polymorphism of the V_χ; repertoire in systemic lupus erythematosus (SLE), we performed Southern blot hybridizations with human gene probes corresponding to the four human V_χ; gene families. In a comparative analysis, non‐lymphoid cell DNA samples from three patients with idiopathic SLE, eight subjects with susceptibility to drug‐induced lupus and seven control individuals were digested with the restriction endonucleases Bam HI, Bg1 II, Eco RI and Hind III, and hybridized sequentially to the four V_χ; family‐specific probes. The restriction patterns on Southern blots revealed a low degree of polymorphism of the human V_χ; gene repertoires of SLE patients and control individuals. This analysis, together with previous parallel studies of the V_χ; locus in lupus‐prone mice, implies that autoantibody hyperproduction in lupus is not associated with major modifications in the structure or genomic organization of immunoglobulin light chain genes.