Seroreactivity against streptococcal DRS (distantly related to SIC) protein is a predictor for end-stage renal failure.

We hypothesized that immunoreactivity against antigens from nephritic strains of Streptococcus pyogenes may be elevated in patients with end-stage renal failure (ESRF). Additionally, we investigated whether a difference in seroreactivity exists between nonindigenous and indigenous (Aboriginal/Torres Strait Islander) patients. To examine these possibilities, antibodies against potentially nephritogenic proteins, streptokinase (Ska1) (from M1), streptococcal pyrogenic exotoxin type B (SpeB) (from M1), the streptococcal inhibitor of complement-mediated cell lysis (SIC) (from M1) and its two variants, closely related to SIC (CRS) (from M57) and distantly related to SIC (DRS) (from M12) were determined in 66 patients and 31 healthy controls by enzyme-linked immunosorbent assays. A significantly higher proportion of patients compared to controls were seropositive to Ska1 (P = 0.004), DRS (P = 0.0003), CRS (P = 0.001), and SIC (P = 0.018). Regression analysis showed that seroreactivity to DRS (r(2) = 0.85, P = 0.001) predicted the development of ESRF and that being diabetic was positively associated with being an ESRF patient (r(2) = 0.37, P < 0.0001) and being indigenous (r(2) = 0.47, P < 0.0001). These results suggest that these ESRF patients were exposed to strains of S. pyogenes that secrete Ska1, DRS, CRS, and SIC and may have pathological significance. No significant difference was observed between the indigenous patients and nonindigenous patients.