Is the blood B-cell subset profile diagnostic for Sjögren syndrome?

OBJECTIVE To evaluate the relevance of the blood B-cell subset profile for the diagnosis of Sjögren syndrome. METHODS The distribution of mature blood B cells from Bm1 through Bm5 was determined in 161 patients, of whom 25 fulfilled the American-European Consensus Group criteria for primary SS (pSS), and 136 served as disease controls. RESULTS The percentage of Bm2 and Bm2' cells was increased in the patients with pSS compared with 54 patients with rheumatoid arthritis (RA) and 18 with systemic lupus erythematosus (SLE) (p<0.001 for the two comparisons). In contrast, those of early Bm5 (eBm5) and Bm5 were decreased in patients with pSS, compared with patients with RA and with SLE (p<0.001 for the two comparisons). The receiver operating characteristic curves allowed for an optimising cut-off value of Bm2+Bm2' cells at 71.1% for 88.0% sensitivity and 83.1% specificity, that of eBm5+Bm5 cells at < or =13.5% for 84.0% sensitivity and 83.1% specificity, and, consequently, that of Bm2+Bm2'/eBm5+Bm5 at > or =5 for 88.0% sensitivity and 84.6% specificity. CONCLUSION Given its presentation as a signature for pSS, relative to RA and SLE, such a distribution of B-cell subsets might provide a useful diagnostic tool.