Serum antibody titers in a systemic lytic therapy with streptokinase

Anaphylactic reactions to streptokinase are rare but potentially life-threatening complications. Gamma E immunoglobulin (IgE) mediated mechanisms, probably due to streptococcal infections, have been implicated. We investigated the value of in vitro laboratory or dermatologic tests in predicting anaphylactic reactions due to streptokinase and the value of antistreptolysin titers (ASL) in predicting the amount of specific IgE (sIgE) and specific gamma G immunoglobulin (sIgG) neutralizing antibodies to streptokinase.

We measured serum levels of total IgE, streptokinase sIgE and sIgG, and ASL in 16 patients before and 9 and 41 days after streptokinase therapy. Immediately before therapy, intracutaneous testing with 100 IU streptokinase was done.

Dermatologic testing did not identify patients prone to allergic reactions. Moreover, not all patients with increased sIgE levels had allergic reactions. These reactions were independent of the dose of streptokinase given. In spite of steroid prophylaxis, allergic reactions occurred in 3 of 16 patients, but none showed life-threatening anaphylaxis. Streptokinase sIgE and sIgG concentrations were closely related to ASL titers.

Plasma levels of sIgG, sIgE, and ASL titers showed a good correlation. We believe ASL titers can be used for the estimation of neutralizing antibodies instead of streptokinase sIgG antibodies. Currently, no laboratory or dermatologic test allows reliable predictions of allergic reactions to streptokinase.