Alterations in lactate dehydrogenase isoenzyme patterns after therapy with streptokinase or streptococcal infection

Serum samples from patients receiving intravenous streptokinase were examined for evidence of interaction in vivo between streptokinase and lactate dehydrogenase (EC 1.1.1.27; LD). We found that this treatment produced a band of LD activity that remained at the electrophoretic origin of LD isoenzyme analysis. Treatment with tissue plasminogen activator produced no such band. The streptokinase-LD complex could be removed from serum by ultracentrifugation. It remained in the circulation for as long as 48 h after streptokinase infusion. A similar phenomenon was observed in a case of pneumococcal sepsis. Examination of supernates from both cultures of several species of Gram-positive cocci revealed interactions between human LD and Streptococcus groups A and C and also Streptococcus pneumoniae. Evidently streptokinase can form complexes with LD in vivo after either streptokinase therapy or infection, with consequent alteration of the LD isoenzyme pattern.