title: Biology of autoreactive extrathymic T cells and B-1 cells of the innate immune system.
abstract: Cumulative evidence has shown that extrathymic T cells can be autoreactive and that B-1 cells may produce autoantibodies. These T and B-1 cells, which form part of the innate immune system, tend to be activated simultaneously when conventional T and B cells are in a suppressive state, for example, when thymic atrophy occurs by stress or involution with aging. In other words, autoreactive T cells and autoantibody-producing B cells are different from thymus-derived T cells and bone marrow-derived B cells. Activated extrathymic T cells and B-1 cells are often observed in numerous autoimmune diseases, aging, malarial infection and chronic graft-versus-host disease. It is thought that the autoreactivity of extrathymic T cells and B-1 cells may be important for the elimination of "abnormal self" tissues or cells. However, over-activation of innate lymphocytes may be related to the onset of disease or self-tissue destruction. However, it must be emphasized that the autoreactivity of innate lymphocytes is not generated by failure of the thymic pathway of T-cell differentiation or the conventional pathway of B-2 cells.
authors.affiliation: Department of Immunology, Niigata University School of Medicine, Niigata, 951-8510, Japan. immunol2@med.niigata-u.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Abo
authors.forename: Chikako
authors.initials: C
authors.lastname: Tomiyama
authors.forename: Hisami
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000375:Aging / Q000276:immunology; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology; D015551:Autoimmunity; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001854:Bone Marrow Cells / Q000276:immunology*; D002908:Chronic Disease; D006086:Graft vs Host Disease / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D008288:Malaria / Q000276:immunology; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology