title: Interleukin-21 Drives Proliferation and Differentiation of Porcine Memory B Cells into Antibody Secreting Cells.
abstract: Immunological prevention of infectious disease, especially viral, is based on antigen-specific long-lived memory B cells. To test for cellular proliferation and differentiation factors in swine, an outbred model for humans, CD21+ B cells were activated in vitro with CD40L and stimulated with purported stimulatory cytokines to characterize functional responses. IL-21 induced a 3-fold expansion in total cell numbers with roughly 15% of all B cells differentiating to IgM or IgG antibody secreting cells (ASCs.) However, even with robust proliferation, cellular viability rapidly deteriorated. Therefore, a proliferation inducing ligand (APRIL) and B cell activating factor (BAFF) were evaluated as survival and maintenance factors. BAFF was effective at enhancing the viability of mature B cells as well as ASCs, while APRIL was only effective for ASCs. Both cytokines increased approximately two-fold the amount of IgM and IgG which was secreted by IL-21 differentiated ASCs. Mature B cells from porcine reproductive and respiratory virus (PRRSV) immune and naïve age-matched pigs were activated and treated with IL-21 and then tested for memory cell differentiation using a PRRSV non-structural protein 7 ELISPOT and ELISA. PRRSV immune pigs were positive on both ELISPOT and ELISA while naïve animals were negative on both assays. These results highlight the IL-21-driven expansion and differentiation of memory B cells in vitro without stimulation of the surface immunoglobulin receptor complex, as well as the establishment of a defined memory B cell culture system for characterization of vaccine responses in outbred animals.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, United States of America.
authors.forename: Michael C
authors.identifier: http://orcid.org/0000-0001-8863-5868
authors.initials: MC
authors.lastname: Rahe
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, United States of America.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Murtaugh
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000166:cytology* / Q000276:immunology; D053264:B-Cell Activating Factor / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D007378:Interleukins / Q000494:pharmacology*; D013552:Swine; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000494:pharmacology; D000098546:Interleukin-21
chemical_list: D053264:B-Cell Activating Factor; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007378:Interleukins; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D000098546:Interleukin-21