title: T Cells in Fish.
abstract: Cartilaginous and bony fish are the most primitive vertebrates with a thymus, and possess T cells equivalent to those in mammals. There are a number of studies in fish demonstrating that the thymus is the essential organ for development of T lymphocytes from early thymocyte progenitors to functionally competent T cells. A high number of T cells in the intestine and gills has been reported in several fish species. Involvement of CD4⁺ and CD8α⁺ T cells in allograft rejection and graft-versus-host reaction (GVHR) has been demonstrated using monoclonal antibodies. Conservation of CD4⁺ helper T cell functions among teleost fishes has been suggested in a number studies employing mixed leukocyte culture (MLC) and hapten/carrier effect. Alloantigen- and virus-specific cytotoxicity has also been demonstrated in ginbuna and rainbow trout. Furthermore, the important role of cell-mediated immunity rather than humoral immunity has been reported in the protection against intracellular bacterial infection. Recently, the direct antibacterial activity of CD8α⁺, CD4⁺ T-cells and sIgM⁺ cells in fish has been reported. In this review, we summarize the recent progress in T cell research focusing on the tissue distribution and function of fish T cells.
authors.affiliation: Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa 252-0880, Japan. nakanishi.teruyuki@nihon-u.ac.jp.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nakanishi
authors.affiliation: Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa 252-0880, Japan. yasuhiroshibasaki@gmail.com.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shibasaki
authors.affiliation: Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa 252-0880, Japan. bryu13505@g.nihon-u.ac.jp.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Matsuura
keywords: CD4; CD8; Cytotoxicity; T cells; Thymus