Rheumatoid factors in systemic lupus erythematosus: association with clinical and laboratory parameters

The prevalence and clinical and laboratory associations of IgM, IgG and IgA rheumatoid factors (RF) were determined in 352 patients with systemic lupu s erythematosus (SLE), IgM, IgG, and IgA class RF were detected in 17.9%, 2 0.5%, and 20.5% of the sera, respectively. RF were associated with sicca sy ndrome, hypergammaglobulinemia, high titer of antinuclear antibodies, anemi a, SSA- and SSB-antibodies, and with the presence of HLA-DR3. RF correlated negatively with nephritis and livedo racemosa. Moreover, we observed an as sociation of RF and parameters of inflammatory activity such as elevated er ythrocyte sedimentation rate (ESR) and leukopenia. Analysis of immunoglobul in classes revealed that laboratory parameters of inflammatory activity, SS A- and SSB-antibodies DR3 correlated with IgA RF only. IgA define a subgrou p of SLE patients characterized by distinct autoimmune phenomena and high d isease activity in the absence of nephritis.