Increased serum levels of interleukin 10 in Sjögren's syndrome; correlation with increased IgG1.
OBJECTIVE
To determine levels of interleukin 10 (IL-10) and IgG subclasses in serum from 53 patients with primary Sjögren's syndrome (SS).


METHODS
Serum levels of IL-10 were measured using specific sandwich ELISA in 25 patients with "definite" SS, 28 with "possible" SS, and 32 healthy controls. Interferon-gamma (IFN-gamma) and transforming growth factor-beta1 (TGF-beta1) were also measured by immunoassays. Immunoglobulin classes, IgG subclasses, and C-reactive protein were measured by nephelometry.


RESULTS
Circulating IL-10 was elevated in 25 patients. The increase reached significance in the group with possible SS (p = 0.03) versus controls. In the group with definite SS, IL-10 level was correlated with IgG1 level (p = 0.01, r = 0.67) and with focus score (p = 0.01). IFN-gamma was undetectable in most patients. TGF-beta1 was higher (not significantly) in possible SS than in definite SS.


CONCLUSIONS
IL-10 is increased in SS and may account for the overproduction of IgG1 in the syndrome. High IL-10 in the absence of increased IgG1 in possible SS suggests that IL-10 may be necessary but not sufficient for IgG1 overproduction and that other factors are involved. Whereas the correlation of IL-10 level with focus score was expected, it is intriguing that IL-10 was more frequently increased in the incomplete (possible) form of SS than the complete (definite) form. Elevated IL-10 may characterize the lower stage of eccrine dysfunction and perhaps contributes to limiting its severity.
Perrier
S
S
Department of Biomathematics and Biostatistics, University of Auvergne, Clermont-Ferrand, France.
Serre
A F
AF
Dubost
J J
JJ
Beaujon
G
G
Plazonnet
M P
MP
Albuisson
E
E
Sauvezie
B
B
D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D007371:Interferon-gamma / Q000097:blood; D016753:Interleukin-10 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012859:Sjogren's Syndrome / Q000097:blood / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000097:blood
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D007371:Interferon-gamma