We have investigated the significance of tumor necrosis factor alpha (TNF-alpha) polymorphism in relation to systemic lupus erythematosus (SLE) and autoantibody production. Typing of HLA-B, -DR and TNF was performed in 81 Caucasian SLE patients and 168 Caucasian controls. The presence of anti-Ro and anti-La antibodies was also determined in patients. The frequency of the TNF2 allele increased in SLE compared with controls [0.24 vs. 0.17, p = 0.04, odds ratio (OR) = 1.6], as did HLA-DR3 (0.25 vs. 0.13, p < 0.01, OR = 2.3) and HLA-B8 (0.23 vs. 0.15, p = 0.02, OR = 2). Although HLA-DR3 showed the strongest disease association, we could not demonstrate association of HLA-DR3 or TNF2 with SLE independently of each other. Within SLE a much stronger association of TNF2 was seen with autoantibody production: anti-Ro antibody (0.39 vs. 0.16, p < 0.001, OR = 3.4) and anti-La antibody (0.43 vs. 0.19, p < 0.001, OR = 3.2). When analyzed independently of each other, however, HLA-DR3 remained significantly associated with autoantibodies, while TNF2 did not. These data suggest that on the B8-DR3 haplotype, TNF-alpha polymorphism may play a role in SLE susceptibility, but it is not primarily associated with autoantibody production.

Low-dose MTX treatment in RA patients leads to an increased plasma homocysteine level. Concomitant folate supplementation with either folic or folinic acid decreases the plasma homocysteine level and consequently protects against potential cardiovascular risks. No relationship was found between the change in homocysteine concentration and the presence or absence of the C677T mutation in the MTHFR gene. Homocysteine metabolism was not associated with efficacy or toxicity of MTX treatment.

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In 30 of 33 human systemic lupus erythematosus (SLE) sera and in 10 sera from MRL/I mice with spontaneous SLE, antibodies against heparan sulfate were detected. The anti-heparan sulfate titers showed a significant correlation with the anti-DNA antibody titers. By inhibition studies it was demonstrated that heparan sulfate could inhibit the binding of anti-DNA antibodies to DNA, whereas DNA could block the binding to heparan sulfate. That this reaction is due to crossreactivity of anti-DNA antibodies was further substantiated by the finding that two monoclonal anti-DNA antibodies also bound to heparan sulfate. Antibodies eluted from human and mouse kidneys with diffuse SLE glomerulonephritis showed a similar binding to DNA and heparan sulfate when these eluted antibodies were tested in vitro. Heparan sulfate is the major glycosaminoglycan constituent of the glomerular basement membrane. Our findings suggest that heparan sulfate might serve as a target antigen in vivo for crossreactive anti-DNA antibodies.

This prospective longitudinal study evaluates the validity and reliability of joint indices (JIs) used to measure disease activity in patients with RA. From seven traditional JIs (Ritchie Articular Index (RAI), Modified RAI, Thompson score, 28 JI, 36 JI, total tender and total swollen joints) 37 'new' JIs were computed by considering three different characteristics of joint inflammation, tenderness, swelling and the combination of tenderness and swelling, and by grading for tenderness and/or weighting for surface area of the joints. Several aspects of validity were investigated, the construct (correlation with radiographic damage), correlational (correlation with ESR, general health) and criterion validity (correlation with a Health Assessment Questionnaire, discrimination between high and low disease activity). It was found that the validity and reliability of traditional JIs do not differ substantially. Graded JIs are almost always more valid than ungraded JIs. Weighted JIs are almost always less valid and reliable than unweighted JIs. Therefore no JI proved to be superior for measuring the disease activity under consideration. Taking simplicity into account the 28 JI, not graded and not weighted, was preferable.