Hypersensitivity reactions to streptokinase in patients with high pre-treatment antistreptokinase antibody and neutralisation titres.

After streptokinase or antistreplase administration, raised antibody levels can persist for many years, but it is unclear if these antibodies can cause allergic reactions following streptokinase re-administration for myocardial re-infarction. Pretreatment antistreptokinase antibody (AB) and neutralisation titres (NT) were measured in 189 consecutive patients (57 received streptokinase or anistreplase). Seven patients had previous exposure to streptokinase or anistreplase; they had high mean (SEM) antibody titres of 1:801 (332) and neutralisation titres of 3.3 (1.7) million units. The 182 patients without previous thrombolysis had mean (SD) antibody titres of 1:25 (3) and neutralisation titres of 0.14 (0.08) million units; nine patients (4.95%), however, had raised antibody titres of > or = 1:160 and neutralisation titres of > or = 0.3 million units. Of the 15 patients with antibody titres of > or = 1:160, three received streptokinase or anistreplase. Hypersensitivity reactions occurred in all three patients--neutralisation titres 0.48, 1.5 and 1.1 million units respectively. Two became severely hypotensive with systolic pressures of 70 mmHg; one developed a serum sickness-like reaction. Importantly, none of the 54 patients with antibody titres of < 1:160 who received streptokinase or antistreplase reacted adversely to the thrombolytic agents (chi 2 with Yates's correction = 38.71, P < 0.01). High antibody titres are associated with hypersensitivity reactions to streptokinase. This has important implications in reinfarction thrombolysis. In patients whose antistreptokinase antibody titres are likely to be raised the avoidance of streptokinase-related thrombolytic agents should be considered.