Objective To determine whether serum levels of B lymphocyte stimulator (BLyS) are elevated in patients with systemic immune–based rheumatic diseases and correlate with serum Ig levels and/or autoantibody titers. Methods Sera from 185 patients with various systemic immune–based rheumatic diseases (95 with systemic lupus erythematosus [SLE], 67 with rheumatoid arthritis [RA], 23 with other diagnoses) were assayed for BLyS and Ig. In 7 patients who required arthrocentesis of a swollen knee, coincident serum and synovial fluid samples were assayed for BLyS. Medical charts were retrospectively reviewed for elevated autoantibody titers and proteinuria within a 1‐month period before or after collection of sera for BLyS and Ig determination. Sera concurrently collected from 48 normal healthy subjects served as controls. Results Serum BLyS levels were elevated in 38 of 185 patients (21%) and correlated significantly with serum IgG levels. Serum BLyS levels did not correlate with the patients' age, sex, race, or medications, but correlated positively with anti–double‐stranded DNA antibody titers among SLE patients and with rheumatoid factor titers among seropositive RA patients. In contrast, serum BLyS levels correlated inversely with nephrotic‐range proteinuria among SLE patients. In every case tested, BLyS levels in clinically inflamed synovial fluids were greater than those in simultaneously obtained sera. Conclusion BLyS may be an important factor in driving polyclonal hypergammaglobulinemia and elevated autoantibody titers in patients with systemic immune–based rheumatic diseases. Local production of BLyS in the joints may contribute to joint pathology. Patients with elevated serum BLyS levels may be ideal candidates for therapeutic targeting of BLyS.

Objective. To assess the overexpression of B lymphocyte stimulator (BLyS) over time in patients with systemic lupus erythematosus (SLE).Methods. Sixty-eight SLE patients were followed up longitudinally for a median 369 days. At each physician encounter, disease activity was assessed by the Systemic Lupus Erythematosus Disease Activity Index, and blood was collected for determination of the serum BLyS level, blood BLyS messenger RNA (mRNA) level, and cell surface BLyS expression. Twenty normal control subjects underwent similar laboratory evaluations.Results. In contrast to the uniformly normal serum BLyS and blood BLyS mRNA phenotypes in control subjects, SLE patients displayed marked heterogeneity, with 50% and 61% of patients manifesting persistently or intermittently elevated serum BLyS and blood BLyS mRNA phenotypes, respectively. Surface BLyS expression by SLE peripheral blood mononuclear cells was also often increased. Treatment of patients who had elevated serum BLyS levels with intensive courses of high-dose corticosteroids resulted in marked reductions in serum BLyS levels, and tapering of the corticosteroid dosage often resulted in increases in serum BLyS levels. Serum BLyS levels generally correlated with anti-double-stranded DNA (anti-dsDNA) titers (in those with detectable anti-dsDNA titers), but changes in serum BLyS levels did not correlate with changes in disease activity in individual patients. Serum BLyS phenotype did not associate with specific organ system involvement.Conclusion. Dysregulation of BLyS over extended periods of time is common in patients with SLE. Neutralization of BLyS activity with an appropriate BLyS antagonist may be therapeutically beneficial.

The early recognition, diagnosis, and prompt treatment of SAPHO syndrome can prevent the unnecessary use of long-term antibiotics or invasive procedures, while rapidly alleviating pain in a majority of affected patients.

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