[Prognostic value of anti-RNP/Sm and anti-Ro/La antibodies in lupus nephropathy].

With the aim to analyze the prognostic value of anti-RNP/Sm and anti-Ro/La antibodies (Ab) in lupus nephropathy, we have studied through Contraimmunoelectrophoresis (CIE) and Immunoblotting (IB) the serum of 63 patients diagnosed of systemic lupus erythematosus. Mean age was 36.5 years (15-71) and 90% were females. We have classified the patients into three subgroups: I, 25 patients without nephropathy; II, 26 patients with evidence of nephropathy (persistent proteinuria and/or microhematuria) and normal renal function; and III, 12 patients with renal failure (servu creatinine > 1.5 mg/dl). 21 patients had kidney biopsy. IB allows to identify a higher number of positive serum, specially in the case of anti-RNP (7.9% CIE vs 28.5% IB) and anti-Sm antibodies (6.3% vs 30.1%). Prevalence of anti-RNP Ab is lower in subgroup III (32% I vs 34% II vs 8% III) (p > 0.05). Anti-Sm Ab are more frequent in group II and are not associated with renal failure (16% vs 54% vs 8%) (p > 0.05). Anti-Ro Ab are related with the absence of nephropathy (52% vs 15% vs 0%) (p < 0.05). We conclude that IB is more sensitive than CIE in the detection of these Ab and its use in Systemic Lupus Erythematosus permits to identify patient subgroups with lesser risk to develop renal failure. Even though our data are preliminary, we suggest that the detection of anti-RNP/Sm and/or anti-Ro/La antibodies are a good prognostic factor in lupus nephropathy.