Advantage of having regulatory T cells requires localized suppression of immune reactions.
The immune system of vertebrates may attack its own body and cause autoimmunity diseases. To prevent autoimmunity, regulatory T cells suppress the activity of the autoreactive effector T cells, but they also interrupt normal immune reactions against foreign antigens. In this paper, we discuss the advantage of having some regulatory T cells by considering the host's ability of coping with foreign antigens and the harm of autoimmunity. Assumptions are as follows: the immature T cells reactive to abundant self-antigens are eliminated, those reactive to rare self-antigen will become regulatory T cells, and those that fail to interact with the antigens to which they are reactive will become effector T cells. Some self-reactive immature T cells may fail to interact with their own target antigens during the limited training period, and will later become effector T cells, causing autoimmunity. Analysis suggests that, having some regulatory T cells can never be advantageous to the host, if activated regulatory T cells suppress effector T cells at any location of the body (global suppression). In contrast, producing some regulatory T cells can be beneficial, if the body is composed of many compartments and regulatory T cells suppress the immune reactions only within the same compartment (localized suppression). This requires regulatory T cells to stop circulating once they are activated by their own target self-antigens.
Saeki
Koichi
K
Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. saekikou@bio-math10.biology.kyushu-u.ac.jp
Iwasa
Yoh
Y
D000818:Animals; D001324:Autoantigens / Q000276:immunology; D015551:Autoimmunity / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D007108:Immune Tolerance / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D018448:Models, Immunological; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D001324:Autoantigens