Raised levels of antistreptokinase antibody and neutralization titres from 4 days to 54 months after administration of streptokinase or anistreplase

Streptokinase and anistreplase are antigenic and their administrationoften leads to antibody formation. These can cause allergicreactions and/or neutralization of streptokinase with resultingsuboptimal treatment. Currently, streptokinase re-administrationis considered appropriate for up to 5 days and from 1 year aftera previous dose. Antistreptokinase antibody and neutralizationtitres (NT) were measured in three groups of patients to determineif this practice is appropriate: 1. (early)—36 patientswhose titres were measured for at least 5 days after thrombolysis;2. (late)—57 patients who received thrombolysis 12–54months previously; 3. (controls)—182 consecutive suspectedmyocardial infarction patients (without previous exposure tothrombolysis). Results were as follows (mean±SEM): 1. (early)—theantibody and/or NT were raised by day 4 in 19.4% of the patients.One patient could have neutralized 1.97 million units (MU) ofstreptokinase by day 4. (Day 4—antibody 1:39±11,NT 0.19±0.05 MU; day 5–1:136±41 and NT 0.7±0.43MU respectively.) 2. (late)—23 patients (40%) had eitherantibody titres 1:160 and/or NT> 1.5 MU. (12–23 months—antibody1:243±43, NT 0.63±0.15 MU; 24–35 months—1:98±31and 0.69±0.22 MU; 36–54 months—1:87±14and 0.54±0.12 MU.) All titres were significantly higherthan the controls (antibody 1:25±3. NT 0.14±0.01MU, P<0.01). After streptokinase or antistreplase, antibodies are raisedfrom 4 days to at least 54 months. It would seem prudent toavoid their re-administration during this time interval.