SDS-PAGE PATTERNS AND POLYMERIC ALBUMIN IN PROTEINURIA OF LUPUS GLOMERULONEPHRITIS

Proteinuria was characterized by SDS-PAGE and by immunoblotting with a ntihuman albumin sera for the detection of urinary polymers of albumin (PA) in 40 patients with biopsy proven lupus glomerulonephritis (LN) (6 pts class III WHO, 24 pts class IV, 10 pts class V) with various cl inical presentations (nephrotic syndrome with normal or impaired renal function, 14 pts; urinary abnormalities with normal or impaired renal function, 21 pts; clinical remission, 5 pts); in 25 pts, for whom the characterization of proteinuria and the renal biopsy were performed a t the same time, the activity and chronicity index scores were calcula ted. The mixed SDS-PAGE patterns, characterized by the presence of low molecular weight proteins, were the more frequently found; the mixed patterns were significantly associated with interstitial Leukocyte inf iltration (p = 0.05) and glomerular sclerosis (p = 0.046) and nonsigni ficantly associated with higher values of serum creatinine; no SDS-PAG E pattern had predictive value on functional outcome at 36 months. Alb umin polymers were present in 67% of pts; in active disease they were present in 33% of class III, in 100% of class IV and in 45% of class V WHO (p = 0.026); PA were not present in 5 pts with clinical remission (4 class IV and 1 class V WHO). The presence of PA was significantly associated with high values (>10) of activity index (p = 0.009) and wi th extracapillary proliferation (p = 0.041). Serum creatinine tvas low er in patients without PA (Scr 1.0 +/- 0.4 mg/dl) than in those with P A (Scr 1.5 +/- 1.0 mg/dl), but the difference was not statistically si gnificant. At 36 months pts without PA had normal and stable renal fun ction, while patients with PA showed a trend toward renal function det erioration (Scr from 1.5 +/- 1.0 to 1.9 +/- 1.4) but the difference wa s not statistically significant. In summary, the characterization of p roteinuria allow to distinguish various patterns, some of which are co rrelated with some histological parameters and with renal functional i mpairment and might be considered biochemical markers of disease sever ity,