title: Antigen-specific immunoglobulin A antibodies secreted from circulating B cells are an effective marker for recent local immune responses in patients with cholera: comparison to antibody-secreting cell responses and other immunological markers.
abstract: Gut-derived lymphocytes transiently migrate through the peripheral circulation before homing back to mucosal sites and can be detected using an ELISPOT-based antibody secreting cell (ASC) assay. Alternatively, transiently circulating lymphocytes may be cultured in vitro, and culture supernatants may be assayed for antigen-specific responses (antibody in lymphocyte supernatant [ALS] assay). The ALS assay has not been validated extensively in natural mucosal infection, nor has the ALS response been compared to the ASC assay and other cholera-specific immunological responses. Accordingly, we examined immune responses in 30 adult patients with acute cholera in Bangladesh, compared with 10 healthy controls, measuring ALS-immunoglobulin A (IgA), ASC-IgA, and serum and fecal IgA responses to two potent Vibrio cholerae immunogens, the nontoxic B subunit of cholera toxin (CtxB) and lipopolysaccharide (LPS) and a weaker V. cholerae immunogen, the mannose-sensitive hemagglutinin (MSHA). We found significant increases of anti-CtxB, anti-LPS, and anti-MSHA IgA in supernatants of lymphocytes cultured 7 days after onset of cholera using the ALS assay. We found that ALS and ASC responses correlated extremely well; both had comparable sensitivities as the vibriocidal responses, and both procedures were more sensitive than fecal IgA measurements. An advantage of the ALS assay for studying mucosal immune responses is the ability to freeze antibodies in supernatants for subsequent evaluation; like the ASC assay, the ALS assay can distinguish recent from remote mucosal infection, a distinction that may be difficult to make in endemic settings using other procedures.
authors.affiliation: International Centre for Diarrhoeal Disease Research, Bangladesh, Centre for Health and Population Research, Mohakhali, Dhaka 1212, Bangladesh. fqadri@icddrb.org
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
authors.forename: Edward T
authors.initials: ET
authors.lastname: Ryan
authors.forename: A S G
authors.initials: AS
authors.lastname: Faruque
authors.forename: Firoz
authors.initials: F
authors.lastname: Ahmed
authors.forename: Ashraful Islam
authors.initials: AI
authors.lastname: Khan
authors.forename: M Monirul
authors.initials: MM
authors.lastname: Islam
authors.forename: Syed M
authors.initials: SM
authors.lastname: Akramuzzaman
authors.forename: David A
authors.initials: DA
authors.lastname: Sack
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Calderwood
mesh_terms: D000328:Adult; D000918:Antibody Specificity; D000921:Antibody-Producing Cells / Q000276:immunology; D000942:Antigens, Bacterial; D001402:B-Lymphocytes / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology; D001459:Bangladesh; D015415:Biomarkers / Q000032:analysis; D001770:Blood Bactericidal Activity; D016022:Case-Control Studies; D002771:Cholera / Q000276:immunology*; D002772:Cholera Toxin / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000737:chemistry; D005260:Female; D036781:Fimbriae Proteins / Q000276:immunology; D006388:Hemagglutinins / Q000276:immunology; D006801:Humans; D018928:Immunity, Mucosal; D007071:Immunoglobulin A, Secretory / Q000032:analysis / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D037601:Mannose-Binding Lectin; D014734:Vibrio cholerae / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D015415:Biomarkers; D006388:Hemagglutinins; D007071:Immunoglobulin A, Secretory; D008070:Lipopolysaccharides; D037601:Mannose-Binding Lectin; C101032:MshA protein, Vibrio cholerae; D036781:Fimbriae Proteins; D002772:Cholera Toxin