EFFECTOR MECHANISMS ACTIVATED BY HUMAN-IGG SUBCLASS ANTIBODIES - CLINICAL AND MOLECULAR ASPECTS

Secondary systemic immune responses are predominantly of the IgG class and passive administration of intravenous Igc, from pooled normal ser um, is an effective prophylactic and/or therapeutic treatment for pati ents with defined immunodeficiencies. However, the proportions of each IgG subclass present within a specific antibody response may differ d ramatically from that of the total IgG pool. For some antigens the res ponse may be essentially restricted to a single subclass and it may be presumed that the antibody isotype produced has an optimal protective role. The clinical consequences of selective IgG subclass deficiency appears to validate this presumption. In this review we emphasize the differences in effector functions activated by the IgG subclasses and hence the mechanisms responsible for the removal and destruction of an tigen/antibody complexes. These studies are relevant to diagnosis and treatment of patients with recurrent infection; the IgG isotype of mon oclonal antibodies selected for passive in vivo therapy; the generatio n of customized antibodies having a pre-determined profile of effector functions and 'immuno-direction' with new vaccines to provoke an anti body response having an isotype profile optimal for the proposed appli cation.