Immunoglobulin V-lambda transcription profiling of systemic lupus erythematosus patients reveals biased usage of genes located near the Jlambda-Clambda segments.

To evaluate the distribution of usage and to quantify the transcription levels of the immunoglobulin lambda variable (IGLV) genes in patients with systemic lupus erythematosus (SLE) and normal individuals (NIs), cDNA samples from peripheral blood lymphocytes were prepared and probed with IGLV-specific oligonucleotides. Because recombinations involving V-lambda pseudogenes are nonproductive, we analysed the IGLV productive repertoire, as cDNAs were copied from IGLV mRNA producing B lymphocytes. Increased expression of the IGLV8a gene in SLE led us to analyse the transcription levels of all IGLV genes. We developed an expression profiling approach to scan the entire V-lambda locus on chromosome 22q11.2. The transcription profiling showed that usually the V-lambda genes located near the Jlambda-Clambda cluster were preferentially expressed in both groups, i.e. patients and NIs, with the expression levels of SLE patients being significantly higher. However, genes displaying peaks of expression independent of Jlambda-Clambda cluster proximity were observed along the IGLV locus. Our data permit us to conclude that there are differences in V-lambda gene expression between SLE patients and NIs, and a preferential usage of genes located near the Jlambda-Clambda cluster. The data also demonstrate the occurrence of Vlambda-Jlambda-Clambda-productive recombinations independent of gene localization along the locus.

Association between EcoRI fragment-length polymorphism of the immunoglobulin lambda variable 8 (IGLV8) gene family with rheumatoid arthritis and systemic lupus erythematosus.

The human immunoglobulin lambda variable 8 (IGLV8) subgroup is a gene family containing three members, one of them included in a monomorphic 3.7-kb EcoRI genomic fragment located at the major lambda variable locus on chromosome 22q11.1 (gene IGLV8a, EMBL accession No. Z73650) at 100% frequency in the normal urban population. The second is a polymorphic RFLP allele included in a 6.0-kb EcoRI fragment at 10% frequency, and the third is located in a monomorphic 8.0-kb EcoRI fragment at 100% frequency, the last being translocated to chromosome 8q11.2 and considered to be an orphan gene. Our Southern blot-EcoRI-RFLP studies in normal individuals and in patients with rheumatoid arthritis (RA) or with systemic lupus erythematosus (SLE), using a specific probe for the IGLV8 gene family (probe pVL8, EMBL accession No. X75424), have revealed the two monomorphic genomic fragments containing the IGLV8 genes, i.e., the 3.7-kb fragment from chromosome 22q11.1 and the 8.0-kb fragment from 8q11.2, both occurring at 100% frequency (103 normal individuals, 48 RA and 28 SLE patients analyzed), but absence of the 6.0-kb IGLV8 polymorphic RFLP allele in all RA or SLE patients. As expected, the frequency of the 6.0-kb allele among the normal individuals was 10%. These findings suggest an association between the absence of the 6.0-kb EcoRI fragment and rheumatoid arthritis and systemic lupus erythematosus.

Association between EcoRI fragment-length polymorphism of the immunoglobulin lambda variable 8 (IGLV8) gene family with rheumatoid arthritis and systemic lupus erythematosus

The human immunoglobulin lambda variable 8 (IGLV8) subgroup is a gene family containing three members, one of them included in a monomorphic 3.7-kb EcoRI genomic fragment located at the major lambda variable locus on chromosome 22q11.1 (gene IGLV8a, EMBL accession No. Z73650) at 100 percent frequency in the normal urban population. The second is a polymorphic RFLP allele included in a 6.0-kb EcoRI fragment at 10 percent frequency, and the third is located in a monomorphic 8.0-kb EcoRI fragment at 100 percent frequency, the last being translocated to chromosome 8q11.2 and considered to be an orphan gene. Our Southern blot-EcoRI-RFLP studies in normal individuals and in patients with rheumatoid arthritis (RA) or with systemic lupus erythematosus (SLE), using a specific probe for the IGLV8 gene family (probe pVL8, EMBL accession No. X75424), have revealed the two monomorphic genomic fragments containing the IGLV8 genes, i.e., the 3.7-kb fragment from chromosome 22q11.1 and the 8.0-kb fragment from 8q11.2, both occurring at 100 percent frequency (103 normal individuals, 48 RA and 28 SLE patients analyzed), but absence of the 6.0-kb IGLV8 polymorphic RFLP allele in all RA or SLE patients. As expected, the frequency of the 6.0-kb allele among the normal individuals was 10 percent. These findings suggest an association between the absence of the 6.0-kb EcoRI fragment and rheumatoid arthritis and systemic lupus erythematosus