EcoRI Restriction Fragment-Length Polymorphism of the Human Immunoglobulin Variable Lambda 8 (IGLV8) Subgroup Reveals a Gene Family

The human immunoglobulin lambda locus (IGL) maps on chromosome 22q11.1–q11.2 and directs the synthesis of lambda-type Ig light chains. This locus is formed by three gene clusters (VA, VB and VC) that encompass the variable coding genes and the J-C cluster plus the joining segments and the constant genes. Recently the variable lambda gene clusters were mapped by the contig methodology which located all the known functional v-lambda genes and pseudogenes. The 30 functional v-lambda genes described so far were subgrouped into ten families (VλI to VλX), but RFLP studies have estimated that the germline repertoire contains about 70 genes. Based on sequence comparisons, we defined specific oligonucleotide primers for the unique IGLV8S1 genedescribed. The cloned 244 bp product obtained from genomic DNA with these primers was sequenced and used as probe in Southern hybridization EcoRI RFLP analysis of Brazilian people. We detected the IGLV8S1 gene in a 3.7 kb EcoRI restriction fragment present in all the individuals analyzed, in agreement with the physical map of the IGL locus. Moreover, we detected an 8.0 kb EcoRI monomorphic fragment and a 6.0 kb EcoRI polymorphic fragment. These data suggest that the IGLV8 subgroup is a gene family.