title: Age-dependent appearance of non-major histocompatibility complex-restricted helper T cells.
abstract: T cells which recognize antigen in association with self major histocompatibility complex (MHC) molecules are positively selected within the thymus. This results in skewing of the T-cell repertoire toward the recognition of antigenic peptides presented by self MHC molecules. While the thymus gland involutes at a relatively young age, bone marrow function and the size of the peripheral T-cell pool are maintained with age. We have investigated the MHC restriction of helper T-cell function for B-cell production of specific antibody in mice of different ages. Splenic helper T cells from 2- to 3-month old mice immunized with phosphocholine-keyhole limpet hemocyanin conjugate were MHC-restricted as defined by their capacity to induce phosphocholine-specific antibody synthesis by syngeneic but not by allogeneic B cells. In contrast, splenic T cells from immunized 18- to 20-month-old mice induced specific anti-phosphocholine antibodies by both syngeneic and allogeneic B cells. No evidence of polyclonal immunoglobulin synthesis was detected. The ability of T cells from old mice immunized with phosphocholine-keyhole limpet hemocyanin to induce phosphocholine-specific antibody synthesis by B cells from allogeneic mice was inhibited by T cells from immunized young mice. These findings suggest that non-MHC-restricted T-cell helper activity in old mice results from the loss of T cells, present in young mice, which suppress non-MHC-restricted helper cells.
authors.affiliation: Department of Medicine, Cornell University Medical College, New York, NY 10021.
authors.forename: C
authors.initials: C
authors.lastname: Russo
authors.forename: E P
authors.initials: EP
authors.lastname: Cherniack
authors.forename: A
authors.initials: A
authors.lastname: Wali
authors.forename: M E
authors.initials: ME
authors.lastname: Weksler
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D005260:Female; D006433:Hemocyanins / Q000276:immunology; D007114:Immunization; D016130:Immunophenotyping; D008285:Major Histocompatibility Complex; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008974:Mollusca; D010767:Phosphorylcholine / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D010767:Phosphorylcholine; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin