Know your enemy or find your friend?—Induction of IgA at mucosal surfaces

Abstract

Most antibodies produced in the body are of the IgA class. The dominant cell population producing them are plasma cells within the lamina propria of the gastrointestinal tract, but many IgA‐producing cells are also found in the airways, within mammary tissues, the urogenital tract and inside the bone marrow. Most IgA antibodies are transported into the lumen by epithelial cells as part of the mucosal secretions, but they are also present in serum and other body fluids. A large part of the commensal microbiota in the gut is covered with IgA antibodies, and it has been demonstrated that this plays a role in maintaining a healthy balance between the host and the bacteria. However, IgA antibodies also play important roles in neutralizing pathogens in the gastrointestinal tract and the upper airways. The distinction between the two roles of IgA ‐ protective and balance‐maintaining ‐ not only has implications on function but also on how the production is regulated. Here, we discuss these issues with a special focus on gut and airways.

Gut Microbiome Alterations Associated with Diabetes in Mexican Americans in South Texas

“…The function of MMP27 has not been well elucidated, but expression was found to be enriched in immunoglobulin G (IgG)/IgM-stimulated B cells ( 27 ). The majority of activated B cells differentiate into plasma cells that produce secretory IgA, which maintains gut homeostasis by coating specific bacterial species to attenuate bacterial invasion and inflammatory responses ( 28 ). Mice lacking IgA exhibited persistent expansion of Proteobacteria and exaggerated inflammation ( 29 ).…”

Progress and challenges in mass spectrometry-based analysis of antibody repertoires

“…The main function of antibodies in the context of the serum and mucosal humoral immune response is antigen recognition, which also facilitates a variety of effector functions such as opsonization for antibody-dependent cytotoxicity, target neutralization, and gut microbiota regulation [1][2][3]. Together, these functions ensure immunological protection (e.g., vaccine responses), their use in monoclonal antibody (mAb) and serum therapy of infection, cancer, and autoimmunity [4][5][6], as well as the harnessing of antibodies as biosensors for medical diagnostics [e.g., antibody-based tests for HIV and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] [7,8].…”

Microbiome and immune-mediated dry eye: a review

“…For example, plasma cells in mucosal tissues, including the gut, produce large amounts of immunoglobulin A (IgA) that neutralise pathogenic bacteria and promote survival of commensal bacteria. 3 In one study, germ-free mice (mice without a gut microbiome) harboured fewer IgA-producing plasma cells compared with control mice. However, plasma cell levels increased significantly after a microbiome was transplanted via faecal transfer from healthy wild-type mice, demonstrating the importance of the microbiome in regulating antibody production and immune responses.…”