title: Subclass of individual IgA-secreting human lymphocytes. Investigation of in vivo pneumococcal polysaccharide-induced and in vitro mitogen-induced blood B cells by monolayer plaque-forming cell assays.
abstract: The subclass of individual human IgA B cells was investigated by means of monolayer plaque-forming cell assays permitting analysis of all IgA-secreting cells as well as of cells secreting IgA anti-pneumococcal polysaccharide antibody. Center cells were examined by indirect immunofluorescence staining with mouse mAb against either of the two IgA subclasses as primary antibodies and FITC-conjugated rabbit anti-mouse Ig as the second antibody. Blood lymphocytes spontaneously secreting IgA (mean 399/10(6) mononuclear cells) produced mainly IgA1 (73%). A similar distribution of subclasses was recorded among IgA-secreting blood cells in PWM- and EBV-stimulated cultures. In contrast, a predominance of IgA2 (54%) was found among IgA-secreting cells (2531/10(6)) isolated from the blood 7 days after in vivo stimulation with pneumococcal polysaccharides, and a similar proportion (51%) of IgA2 producing cells was found among IgA anti-pneumococcal polysaccharide-secreting cells. It was thus confirmed that IgA1 is the predominant subclass of blood IgA-secreting cells in general. However, the high percentage of IgA2-secreting cells found after vaccination with pneumococcal polysaccharides suggests that these Ag have an unusually high ability to activate IgA2 B cells, or that the B cells stimulated originate from lymphatic tissues with a high frequency of IgA2 committed cells.
authors.affiliation: Department of Paediatrics, Rigshospitalet, Copenhagen, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Heilmann
authors.forename: T
authors.initials: T
authors.lastname: Barington
authors.forename: T
authors.initials: T
authors.lastname: Sigsgaard
mesh_terms: D000328:Adult; D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000378:metabolism; D001428:Bacterial Vaccines / Q000008:administration & dosage*; D001666:Binding Sites, Antibody; D006462:Hemolytic Plaque Technique; D004854:Herpesvirus 4, Human; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis* / Q000145:classification; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation; D008875:Middle Aged; D022242:Pneumococcal Vaccines; D011043:Pokeweed Mitogens; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines; D022242:Pneumococcal Vaccines; D011043:Pokeweed Mitogens; D007073:Immunoglobulin E