Correlation of serum B lymphocyte stimulator and beta2 microglobulin with autoantibody secretion and systemic involvement in primary Sjogren's syndrome.
BACKGROUND
In primary Sjögren's syndrome (pSS), extraglandular involvement might result from more intense stimulation of autoreactive B cells. Thus markers of B cell activation could be useful in the clinical assessment of this disease.


OBJECTIVE
To investigate the association of serum B lymphocyte stimulator (BLyS) and beta2 microglobulin with autoantibody production and extraglandular involvement in pSS.


METHODS
Serum concentrations of BLyS and beta2 microglobulin were analysed in 177 patients with pSS according to the American-European consensus group criteria. Serum beta2 microglobulin was determined serially in 25 patients.


RESULTS
Autoantibody secretion (presence of anti-SSA antibody alone or of both anti-SSA and anti-SSB) was associated with increased serum BLyS and beta2 microglobulin. No correlation was found between BLyS and beta2 microglobulin levels (p = 0.36). Serum concentrations of beta2 microglobulin and C reactive protein and positive anti-SSB antibody results were associated with extraglandular involvement on univariate analysis (p<10(-4), p = 0.003, and p = 0.004, respectively). Serum beta2 microglobulin was also significantly increased in patients with extraglandular involvement without autoantibodies (mean (SD): 1.75 (0.7) v 1.39 (0.5) mg/l, p = 0.039). Multivariate analysis showed that extraglandular involvement was associated only with increased serum beta2 microglobulin (p = 0.035, odds ratio = 2.78 (95% confidence interval, 1.07 to 7.22)). Among the 25 patients who had serial determinations of serum beta2 microglobulin, the concentrations were increased in all those with disease flare and decreased in three following treatment. Serum BLyS, gamma globulin, IgG, and rheumatoid factor levels were not associated with features of systemic involvement.


CONCLUSIONS
Serum beta2 microglobulin and BLyS reflect B cell activation in different ways in pSS. Serum beta2 microglobulin assessment could be helpful as an activity marker in pSS.
Gottenberg
J-E
JE
Service de Rhumatologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin Bicêtre, France.
Busson
M
M
Cohen-Solal
J
J
Lavie
F
F
Abbed
K
K
Kimberly
R P
RP
Sibilia
J
J
Mariette
X
X
D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear / Q000097:blood; D001323:Autoantibodies / Q000097:blood*; D053264:B-Cell Activating Factor; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D008875:Middle Aged; D012859:Sjogren's Syndrome / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha; D001613:beta 2-Microglobulin / Q000032:analysis*
D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D053264:B-Cell Activating Factor; D015415:Biomarkers; D003176:Complement C3; D003181:Complement C4; D008565:Membrane Proteins; C505719:TNFSF13B protein, human; D014409:Tumor Necrosis Factor-alpha; D001613:beta 2-Microglobulin