title: Protective antigen-specific memory B cells persist years after anthrax vaccination and correlate with humoral immunity.
abstract: Anthrax Vaccine Adsorbed (AVA) generates short-lived protective antigen (PA) specific IgG that correlates with in vitro toxin neutralization and protection from Bacillus anthracis challenge. Animal studies suggest that when PA-specific IgG has waned, survival after spore challenge correlates with an activation of PA-specific memory B cells. Here, we characterize the quantity and the longevity of AVA-induced memory B cell responses in humans. Peripheral blood mononuclear cells (PBMCs) from individuals vaccinated ≥3 times with AVA (n = 50) were collected early (3-6 months, n = 27) or late after their last vaccination (2-5 years, n = 23), pan-stimulated, and assayed by ELISPOT for total and PA-specific memory B cells differentiated into antibody secreting cells (ASCs). PA-specific ASC percentages ranged from 0.02% to 6.25% (median: 1.57%) and did not differ between early and late post-vaccination individuals. PA-specific ASC percentages correlated with plasma PA-specific IgG (r = 0.42, p = 0.03) and toxin neutralization (r = 0.52, p = 0.003) early post vaccination. PA-specific ASC percentages correlated with supernatant anti-PA both early (r = 0.60, p = 0.001) and late post vaccination (r = 0.71, p < 0.0001). These data suggest PA-specific memory B cell responses are long-lived and can be estimated after recent vaccination by the magnitude and neutralization capacity of the humoral response.
authors.affiliation: Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. Lori-Garman@omrf.org.
authors.forename: Lori
authors.initials: L
authors.lastname: Garman
authors.affiliation: Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. Ken-Smith@omrf.org.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Smith
authors.affiliation: Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. Darise-Farris@omrf.org.
authors.forename: A Darise
authors.initials: AD
authors.lastname: Farris
authors.affiliation: Military Vaccine Agency-Vaccine Healthcare Centers Network, Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, MD 20889, USA. michael.r.nelson.mil@health.mil.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Nelson
authors.affiliation: Military Vaccine Agency-Vaccine Healthcare Centers Network, Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, MD 20889, USA. renata.j.engler.mil@health.mil.
authors.forename: Renata J M
authors.initials: RJ
authors.lastname: Engler
authors.affiliation: Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. Judith-James@omrf.org.
authors.forename: Judith A
authors.initials: JA
authors.lastname: James
mesh_terms: D000328:Adult; D022122:Anthrax Vaccines; D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001408:Bacillus anthracis / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D006801:Humans; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000276:immunology*; D007963:Leukocytes, Mononuclear; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D022122:Anthrax Vaccines; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D007074:Immunoglobulin G; C030325:anthrax toxin