Immunoglobulin A-mediated protection against Bordetella pertussis infection

Infection with Bordetella pertussis, the causative agent of pertussis (whooping cough) in humans, is followed by the production of antibodies of several isotypes, including immunoglobulin A (IgA). Little is known, however, about the role of IgA in immunity against pertussis. Therefore, we studied targeting of B. pertussis to the myeloid receptor for IgA, Fc alpha RI (CD89), using either IgA purified from immune sera of pertussis patients or bispecific antibodies directed against B. pertussis and FcaRI (CD89 BsAb). Both IgA and CD89 BsAb facilitated Fc alpha RI-mediated binding, phagocytosis, and bacterial killing by human polymorphonuclear leukocytes (PMNL) and PMNL originating from human Fc alpha RI-transgenic mice. Importantly, Fc alpha RI targeting resulted in enhanced bacterial clearance in lungs of transgenic mice. These data support the capacity of IgA to induce anti-B. pertussis effector functions via the myeloid IgA receptor, Fc alpha RI. Increasing the amount of IgA antibodies induced by pertussis vaccines may result in higher vaccine efficacy.