A POSSIBLE ROLE OF PREEXISTING IGM IGG ANTIBODIES IN DETERMINING IMMUNE-RESPONSE TYPE/

On the basis of the data indicating the existence of two types of immu ne-protection, namely macrophage-mediated and mast cell-basophil-media ted, it is argued that by reacting with potential pathogens, pre-exist ing IgM and IgG antibodies (both natural and induced by environmental microflora) might promote involvement of macrophages in the presentati on process, favouring the generation of pathogen-specific T helper 1 ( Th1), bur not Th2, responses, Alternatively, the failure of these anti bodies to effectively recognize pathogens might be associated with act ive involvement of pathogen-specific B cells in presenting Ag and, as a consequence, with the predominant development of Th2, rather than Th 1, responses.