title: Rhesus macaque rectal and duodenal tissues exhibit B-cell sub-populations distinct from peripheral blood that continuously secrete antigen-specific IgA in short-term explant cultures.
abstract: It is becoming increasingly obvious that evaluation of a vaccine aimed at preventing HIV infection should include assessment of induced immunity at mucosal sites of viral entry. Among the most salient immune responses are viral-specific antibodies. A recent report on IgA-secreting plasma cells in human duodenal explants prompted us to examine similar duodenal and rectal biopsies of rhesus macaques, a key animal model for pre-clinical HIV/SIV vaccine studies, and characterize the local resident B-cells. Here we report that non-human primate rectal explants possess similar levels of B-cells as duodenal explants. We characterize the antibody isotype expression on mucosal memory B-cells and show for the first time that the B-cell memory subsets of the duodenum and rectum are distinct from those of PBMC, not only by essentially lacking CD27(+) cells, as previously reported for uninfected macaques (Titanji et al., 2010), but also in being mostly IgD(-). SIV- and SHIV-infected macaques had fewer total IgA-secreting cells in rectal tissue compared to naïve macaques. As expected, the fractions of B-cells with surface expression of IgA were dominant in the rectal and duodenal explants whereas in PBMC IgG surface expression was dominant among IgD(-) B-cells. Mucosal antibody secreting cells were found to be predominantly plasma cells/plasma blasts based on their lack of response to stimulation. Importantly, short-term culture of rectal explants of SIV- and SHIV-positive animals led to secretion of Env-specific IgA into the culture supernatant which could be easily measured by ELISA. Collection of such culture supernatant over several days allows for accumulation of mucosal antibody in amounts that should enable antibody purification, characterization, and use in functional assays. Rectal explants can be readily obtained and unequivocally identify the mucosal tissue as the source of antibody. Overall they facilitate evaluation of mucosal vaccines.
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thomas
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Demberg
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Vargas-Inchaustegui
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Xiao
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Iskra
authors.initials: I
authors.lastname: Tuero
authors.affiliation: Biostatistics and Data Management Section, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: David
authors.initials: D
authors.lastname: Venzon
authors.affiliation: Advanced BioScience Laboratories, Inc., Rockville, MD, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Weiss
authors.affiliation: Advanced BioScience Laboratories, Inc., Rockville, MD, USA.
authors.forename: James
authors.initials: J
authors.lastname: Treece
authors.affiliation: Section on Immune Biology of Retroviral Infection, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. Electronic address: guroffm@mail.nih.gov.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Robert-Guroff
mesh_terms: D000818:Animals; D001706:Biopsy; D004386:Duodenum / Q000276:immunology*; D007070:Immunoglobulin A / Q000096:biosynthesis*; D007156:Immunologic Memory; D008253:Macaca mulatta; D010950:Plasma Cells / Q000276:immunology*; D012007:Rectum / Q000276:immunology*; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology; D015302:Simian Immunodeficiency Virus; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000378:metabolism
chemical_list: D007070:Immunoglobulin A; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
keywords: AIDS vaccine; IgA; Memory B-cells; Mucosal explant cultures; SIV/SHIV infected rhesus macaques