Prevalence of circulating antibodies against a streptokinase C-terminal peptide in normal blood donors

Streptokinase (SK) is a streptococcal protein widely used as a thrombolytic agent. Anti-SK antibodies (Abs) are found in most individuals due to commo n streptococcal infections. The presence of these Abs increases the possibi lity of allergic reactions and may reduce the thrombolytic efficacy of SK u pon a first therapy. Previous studies report on the immunodominance of the SK C-terminus and the role of this region in plasminogen (Plg) activation. The aim of this study was to assess the prevalence of circulating Abs to th e SK C-terminus in normal blood donors. Sera from 1008 subjects aged 30 to 60 years were tested by Ultra-Micro-ELISA using a synthetic peptide resembl ing the SKC-2 C-terminus. An overall prevalence of 30.4% was found. Prevale nce was significantly higher among male than among female donors (RR = 1.70 , 1.13 < CI < 2.55). No age effect was observed. This is the first extensiv e study about Abs directed against a particular region of SK in normal subj ects. (C) 1999 Academic Press.