V-H GENE-FAMILY REPRESENTATION IN PERIPHERAL ACTIVATED B-CELLS FROM SYSTEMIC LUPUS-ERYTHEMATOSUS (SLE) PATIENTS

A semiquantitative polymerase chain reaction (PCR) assay described in this study has been used to analyse the V(H)1, V(H)3 and V(H)4 reperto ire expressed by total IgM(+) and IgG(+) B cells from normal individua ls and lupus patients. This approach consists of a combination of B ce ll selection, utilization of the anchored PCR technique to avoid techn ical bias in the amplification of different V-H gene family cDNA templ ates, and screening of the amplified IgM or IgG cDNA rearrangements by family-specific oligonucleotide probes. In four lupus patients, V-H f amily representation in IgM(+) and IgG(+) in vivo activated B cells, s elected by anti-CD71 antibody, and in total CD19(+) B cells were compa red. In all patients, V(H)4 gene family segments were preferentially u nderrepresented in IgM(+) activated B cells. In IgG(+) B cells the res ults suggest that V(H)4 expression is variable, depending on the phase of the disease. Polyclonal B cell activation, which is usually consid ered as being the first event in autoantibody production in SLE, canno t explain our results. The data evoke the possible involvement of a V( H)4-specific B cell superantigen in the onset or development of SLE. T his hypothesis is also supported by the sequence conservation of the f ourth beta loop-a putative superantigen binding site-of functional V(H )4 gene segments which are preferentially used by anti-dsDNA lupus ant ibodies of established clones and hybridomas.