title: Secondary intratracheal infection of mice with Mycoplasma pulmonis generates IgG1 memory B cells.
abstract: Mycoplasma pulmonis, a rodent respiratory pathogen, was used to study the immune response in the bronchus-associated lymphoid tissue (BALT) and other lymphoid tissues. Infection of BALB/c mice intratracheally (i.t.) with M. pulmonis results in an increased frequency of antigen-sensitive B cells at the site of priming. Upon secondary i.t. challenge, the frequency of antigen-specific B cells rises significantly in BALT, in peripheral blood and, to a lesser extent, in lymphoid tissues distal to the site of priming, i.e., spleen and Peyer's patches. The predominant isotype of anti-M. pulmonis antibody expressed by clones grown in thymus-dependent splenic fragment cultures from B cells taken from all tissues is IgG1. Elimination of accompanying T cells in inocula from euthymic BALB/c mice or lack of T cells at the time of in vivo priming of athymic mice does not change the isotype profile of clones grown from M. pulmonis-specific B cells. The splenic fragment cultures used to grow these clones do not distort the isotype display towards IgG1 expression, since clones grown from either primed or unprimed B cells of other specificities (i.e., trinitrophenyl--TNP) express any or all isotypes in a variety of combinations. The majority of M. pulmonis-specific clonal precursor B cells are sIgG1+/IgD-. All these findings suggest that the potential to give rise to predominantly IgG1-secreting clones in vitro is intrinsic to the M. pulmonis-specific memory B cells primed in vivo.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology*; D001980:Bronchi / Q000276:immunology; D007114:Immunization; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007156:Immunologic Memory; D007267:Injections; D008221:Lymphoid Tissue / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009174:Mycoplasma / Q000276:immunology*; D009175:Mycoplasma Infections / Q000276:immunology*; D012141:Respiratory Tract Infections / Q000276:immunology*; D014132:Trachea
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G