Antistreptokinase platelet-activating antibodies are common and heterogeneous

Abstract

Summary. Background: Platelet activation by antistreptokinase (SK) antibodies could impair the clinical effect of SK administration. Objective: To better describe anti-SK antibodies with particular emphasis on procoagulant activities as a result of platelet activation. Patients and methods: Sera were collected from 146 patients with coronary artery disease: non-SK-treated, 95 from mainland France, 31 from French Polynesia; 20 patients from mainland in year 2 after SK treatment. Serum-induced SK-dependent platelet activation resulting in procoagulant activities was assessed with washed platelets from five donors representative of the known patterns of reactivities to IgG. Results: Concentrations (2-5252 mg mL À1 ) and fibrinolytic neutralization titres (< 10 to >1280) were found in the expected wide range and correlated (r ¼ 0.66, P < 0.0001). Platelet activation was detected with 145 samples, but varied in intensity and pattern (depending on the donors), although there was no systematic hierarchy; it was presumably due to IgG (inhibited by an IgG Fc receptor-blocking antibody and recovered in the IgG fraction) and only partially affected by aspirin. Marked platelet activation could be detected in samples with concentration as low as 2 mg mL À1 , and/or no detectable neutralizing titers. The way of immunization to SK was not found to influence the functional profile of antibodies. Conclusion: Anti-SK platelet-activating antibodies are widespread, heterogeneous, poorly predictable on the basis of their antifibrinolytic effect and strong enough to trigger procoagulant activities. Their clinical relevance should be formally assessed, using patients' own platelets for detection owing to the variation of platelet reactivity.

Fibrinolytic Bacterial Enzymes with Thrombolytic Activity

“…Because streptococcal infections are common, a detectable level of antibodies against streptokinase occurs in most populations (Kazmi et al 2002). Many different antistreptokinase platelet-activating antibodies are known to exist and occur widely (Regnault et al 2003).…”

Streptokinase—the drug of choice for thrombolytic therapy

“…Many different anti-SK platelet-activating antibodies are known to exist and occur widely [105]. Extensive work has been reported on the identification of antigenic regions of SKs [106][107][108][109].…”