Interleukin-21 drives proliferation and differentiation of porcine memory B cells into antibody secreting cells

Michael C. Rahe, Michael P. Murtaugh

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7 Scopus citations


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.

Original languageEnglish (US)
Article numbere0171171
JournalPloS one
Issue number1
StatePublished - Jan 2017

Bibliographical note

Funding Information:
This research was supported by United States Department of Agriculture National Institute of Food and Agriculture grant 2015-06966 ( and a National Institutes of Health fellowship to MCR from the training grant T32 OD010993 ( We thank Diem Ngo for technical assistance. The research was supported by USDA NIFA grant 2015-06966 and an NIH fellowship to MCR from the training grant T32 OD010993.

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