Objective: Lupus nephritis has often been associated with anti-DNA, but, based on the findings in eluate studies, it appears that other antigen-antibody reactions, such as those involving anti-Ro/SS-A, anti-nuclear RNP (anti-nRNP), and/or anti-Sm, may also contribute to the pathogenesis of nephritis. In the present investigation, we identified and further studied a distinctive precipitin profile present in black women with nephritis.
Methods: Longitudinal clinical and serologic studies of a cohort of university-based systemic lupus erythematosus (SLE) patients (n = 120) were carried out over an 8-year period.
Results: A subset of 20 black female patients was identified, of whom 8 had lupus nephritis (group I) and 12 did not (group II). Group I was characterized by a distinct precipitin profile consisting of anti-Ro/SS-A, anti-SM, and anti-nRNP, but no anti-La/SS-B. SLE disease duration at presentation was significantly shorter in group I than in group II (mean 1.94 years versus 5.21 years; P = 0.02). The distinctive precipitin profile of anti-Ro/SS-A, anti-Sm, and anti-nRNP occurred exclusively in group I patients (6 of 8, versus 0 of 12 in group II; P < 0.001). In white lupus nephritis patients, this precipitin profile was not seen.
Conclusion: While the mechanism responsible for the relationship of this distinctive serologic profile to the development of nephritis in black female lupus patients remains to be determined, its presence may be used as a marker for severe and progressive renal disease.