Does rheumatoid factor protect lupus patients from the development of nephritis?

It has been suggested again recently that the presence of rheumatoid factor (RF) in the serum of patients with systemic lupus erythematosus (SLE) protects them from the development of nephritis. In this study the RF is measured by standard latex test and by radioimmunoassay to detect IgM, IgA, and IgG isotypes, in patients with SLE with (26 patients) and without (25 patients) renal involvement, and in a control group of 21 patients with idiopathic renal disease. In addition, patients with SLE and nephritis were tested during active and inactive phases of their disease. No significant protective effect was observed from the presence of RF.