title: B cells.
abstract: B cells are an important component of adaptive immunity. They produce and secrete millions of different antibody molecules, each of which recognizes a different (foreign) antigen. The fact that humans express a very large repertoire of antibodies is due to the complex mechanism of V(D)J recombination of immunoglobulin (Ig) genes as well as other processes including somatic hypermutation, gene conversion and class switching. The B cell receptor (BCR) is an integral membrane protein complex that is composed of two Ig heavy chains, two Ig light chains and two heterodimers of Igalpha and Igbeta. To eliminate foreign antigens, B cells cooperate with other cells of the immune system including macrophages, dendritic cells and T cells. B cell development is a tightly controlled process in which over 75% of the developing cells become apoptotic because of inappropriate immunoglobulin gene rearrangements or recognition of self antigens by Igs. Hence, the majority of B cell-associated disorders are caused by the incorrect function of genes/proteins involved in B cell development.
authors.affiliation: Department of Biological and Environmental Sciences, Division of Biochemistry, P.O. Box 56, FI-00014 University of Helsinki, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Ollila
authors.forename: Mauno
authors.initials: M
authors.lastname: Vihinen
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D015322:Gene Rearrangement, B-Lymphocyte; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007137:Immunoglobulin alpha-Chains / Q000235:genetics; D007136:Immunoglobulins / Q000172:deficiency; D008213:Lymphocyte Activation; D008954:Models, Biological; D011947:Receptors, Antigen, B-Cell / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology; D045567:VDJ Recombinases / Q000235:genetics
chemical_list: D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007137:Immunoglobulin alpha-Chains; D007136:Immunoglobulins; D011947:Receptors, Antigen, B-Cell; D045567:VDJ Recombinases