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 ⩽13.5% for 84.0% sensitivity and 83.1% specificity, and, consequently, that of Bm2+Bm2′/eBm5+Bm5 at ⩾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.