VARYING TITERS OF NEUTRALIZING ANTIBODIES TO STREPTOCOCCAL SUPERANTIGENS IN DIFFERENT PREPARATIONS OF NORMAL POLYSPECIFIC IMMUNOGLOBULIN-G - IMPLICATIONS FOR THERAPEUTIC EFFICACY

Inasmuch as normal intravenous polyspecific immunoglobulin G (IVIG) ne utralizes the activity of a wide spectrum of superantigens, it may be an efficient adjunctive therapy for diseases associated with superanti gen-producing organisms, including severe group A streptococcal diseas es. The neutralizing activity against purified superantigens, streptoc occal pyrogenic exotoxins (Spe), and a mixture of superantigens presen t in culture supernatant of clinical group A streptococcal isolates wa s determined for five IVIG preparations, A significant variation among different MG preparations (P < .05) and different lots of the same IV IG brand (P < .044) was found, Neutralization of SpeA activity was sig nificantly lower than that of other streptococcal superantigens (P < . 05); however, there was no correlation between SpeA binding and SpeA n eutralizing activity in different IVIGs. Plasma samples obtained from patients after IVIG infusion varied in their titers of neutralizing an tibodies to culture supernatants prepared from their respective isolat es, and this variation paralleled differences in the neutralizing tite r of the IVIG lot administered to each patient studied, The study sugg ests that complete neutralizing activity may be achieved by optimizing the type and/or dose of MG used in treatment.