Interleukin 6 and autoantibodies in juvenile rheumatoid arthritis.
OBJECTIVE
To assess whether interleukin 6 (IL-6) may influence autoantibody production, the correlation of rheumatoid factors (RF) and antitype II collagen antibodies with IL-6 was determined in children with juvenile rheumatoid arthritis (JRA).


METHODS
IL-6 was measured by proliferation of the B-9 cell line or by ELISA: IgG, IgA, and IgM RF were measured by ELISA:


RESULTS
Plasma IL-6 levels were higher in patients with polyarticular JRA than controls. In serial studies, the presence of a greater number of RF isotypes and IgG antinative type II collagen antibodies correlated with higher IL-6 levels [1650 x divided by 3.4 vs 831 x divided by 4.4, p < 0.01 (geometric mean x divided by SD); and 1828 x divided by 5.9 vs 646 x divided by 4.1, p < 0.005, respectively]. The change in RF isotype expression most often involved IgG or IgA RF. In vitro IgG RF production increased in one and became detectable in another 2 cases upon the addition of IL-6 to B cell cultures.


CONCLUSIONS
Our results suggest that IL-6 may promote the production of IgG and IgA RF and IgG antinative type II collagen antibodies.
Oen
K
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Department of Paediatrics and Child Health, University of Manitoba, Winnipeg, Canada.
Danell
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G
D000293:Adolescent; D000974:Antibodies, Antinuclear / Q000032:analysis; D000936:Antigen-Antibody Complex / Q000032:analysis / Q000276:immunology; D001171:Arthritis, Juvenile / Q000097:blood / Q000453:epidemiology / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology; D002455:Cell Division; D002478:Cells, Cultured; D002648:Child; D003094:Collagen / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000737:chemistry / Q000276:immunology / Q000502:physiology; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology / Q000502:physiology; D007075:Immunoglobulin M / Q000737:chemistry / Q000276:immunology / Q000502:physiology; D015850:Interleukin-6 / Q000097:blood* / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D012217:Rheumatoid Factor / Q000032:analysis* / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology
D000974:Antibodies, Antinuclear; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015850:Interleukin-6; D003094:Collagen; D012217:Rheumatoid Factor