[Formation of specific IgG antibodies in l-asparaginase treatment. Distribution of IgG subclasses].

During l-Asparaginase (l-Asp) treatment the development of specific antibodies of IgG isotype is frequently observed. In most instances elevated IgG antibodies to l-Asp activate the complement system and induce allergic reactions following l-Asp infusion. However, in some cases no adverse reactions and no activation of complement are noticed, despite the presence of elevated anti-l-Asp levels. We studied the development of specific IgG antibodies to l-Asp in different subclasses in 12 children who had produced high levels of specific IgG. Results showed that all patients had elevated levels of IgG1. In 5 cases we were able to demonstrate the development of specific IgG3 antibodies and in 1 case of IgG4 antibody. Patients with high levels of IgG3 (above 100 AU) had the highest risk for subsequent anaphylaxis. Thus, subclass-specific determination of antibodies to l-Asparaginase might improve the estimation of the risk of anaphylaxis prior to 1-Asp infusions.