Fc receptor-mediated immunity against Bordetella pertussis

The relevance of specific Abs for the induction of cellular effector functions against Bordetella pertussis was studied. IgG-opsonized B. pertussis was efficiently phagocytosed. by human polymorphonuclear leukocytes (PMN). This process was mediated by the PMN IgG receptors, Fc gamma RIIa (CD32) and Fc gamma RIIIb (CD16), working synergistically. Furthermore, these Fc gammaR triggered efficient PMN respiratory burst activity and mediated transfer of B. pertussis to lysosomal compartments, ultimately resulting in reduced bacterial viability. Bacteria opsonized with IgA triggered similar PMN activation via Fc gamma alphaR (CD89). Simultaneous engagement of Fc alpha R1 and Fc gammaR by B. pertussis resulted in increased phagocytosis rates, compared with responses induced by either isotype alone. These data provide new insights into host immune mechanisms against B. pertussis and document a crucial role for Ig-FcR interactions in immunity to this human pathogen.