title: Ontogenic development of "natural" and induced plaque-forming cell isotypes in normal mice.
abstract: The numbers of cells and background plaque-forming cells (PFC) in the spleen of C3H/HeJ mice increase exponentially during the first 2 weeks after birth, but much slower in bone marrow (BM). IgG1 and IgG2a PFC are the first non-IgM PFC detectable, while IgG3 and IgA PFC appear only around weaning. Adult-type PFC numbers and isotype pattern are present in spleen and BM at 4 and 15 weeks, respectively. Neonatal splenic C3H/Tif B cells produce non-IgM Ig classes in vitro in response to polyclonal activation by lipopolysaccharide or by helper T cells. These responses are of low magnitude during the first 2 weeks of life, but both secreted and membranebound IgG1 and IgG3 isotypes are detectable already a few days after birth, in a pattern that is identical to that typical of T cell-dependent or independent responses of adult cells. These results indicate full maturity of B cells in "switch" abilities already from birth, in spite of a general deficiency in terminal maturation. In addition, they demonstrate the complexity of isotype regulation in "background" antibody production in vivo.
authors.forename: M
authors.initials: M
authors.lastname: Björklund
authors.forename: S
authors.initials: S
authors.lastname: Pettersson
authors.forename: A
authors.initials: A
authors.lastname: Coutinho
mesh_terms: D000367:Age Factors; D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology*; D000955:Antigens, T-Independent / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D007136:Immunoglobulins / Q000096:biosynthesis* / Q000145:classification; D051379:Mice; D008809:Mice, Inbred C3H; D013154:Spleen / Q000166:cytology / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D000955:Antigens, T-Independent; D007136:Immunoglobulins