Defense mechanisms involving Fc-dependent functions of immunoglobulin A and their subversion by bacterial immunoglobulin A proteases.

INTRODUCTION ..................................................................... 296 DIRECT EFFECTOR FUNCTIONS OF S-IgA ..................................................................... 297 Inhibition of Microbial Adherence and Colonization ..................................................................297 Toxin and Enzyme Neutralization ..................................................................... 297 Virus Neutralization ..................................................................... 297 Inhibition of Antigen Absorption ..................................................................... 298 INDIRECT EFFECTOR FUNCTIONS OF IgA ..................................................................... 298 Interactions of IgA with Innate Humoral Defense Factors ...........................................................298 Complement..................................................................... 298 Lactoferrin, lactoperoxidase, and lysozyme ..................................................................... 298 Mucin..................................................................... 298 IgA-Dependent Cell-Mediated Effector Functions ..................................................................... 298 Phagocytosis..................................................................... 299 Antibody-dependent cell-mediated cytotoxicity ..................................................................... 299 Hepatobiliary transport ..................................................................... 299 ANTI-INFLAMMATORY AND SHIELDING EFFECTS OF IgA....................................................299 INTERFERENCE WITH IgA-MEDIATED DEFENSE MECHANISMS BY BACTERIAL IgA PROTEASES ..................................................................... 299 ACKNOWLEDGMENTS ..................................................................... 301 LITERATURE CITED..................................................................... 301