Induction of interleukin 2 receptor beta chain expression by self-recognition in the thymus.
1-2% of adult mouse thymocytes express the T cell receptor alpha/beta (TCR-alpha/beta) together with the interleukin (IL) 2R beta (p70), but not the alpha (p 55) chain. We show that the previously described alpha/beta-TCR +CD4-8- and the partially overlapping Ly6C+ thymocytes are contained within this subset. Most IL-2R beta+ alpha/beta-TCR+ cells have a mature and activated (heat stable antigen [HSA]-, thymic shared antigen 1 [TSA-1]-, CD44high, CD69+) phenotype. Overrepresentation of V beta 8.2 in both CD4-8- and CD4 and/or CD8+ IL-2R beta+ thymocytes suggests that IL-2R beta expression is induced by a TCR-mediated activation event. In mice transgenic for an H-2Kb-specific TCR, IL-2R beta+ cells were abundant under conditions of mainstream negative selection, i.e., in the presence of Kb, but absent under conditions of mainstream positive selection or in a nonselecting environment. Together, these results show that in addition to clonal deletion, self-recognition by immature thymocytes leads to phenotypic maturation of a small subset of thymocytes expressing IL-2R beta. IL-2-deficient mice contain normal numbers of IL-2R beta+ alpha/beta-TCR+ thymocytes, indicating that like mainstream T cell development, this minor pathway of positive selection does not depend on IL-2. However, in the absence of IL-2, the CD4/CD8 subset composition of IL-2R beta+ thymocytes is skewed towards CD4-8+, mostly at the expense of CD4-8-. A possible relevance of this finding for the development of the immune pathology of IL-2-deficient mice is discussed.
Institute of Virology and Immunobiology, University of Würzburg, Germany.
T
T
Hanke
R
R
Mitnacht
R
R
Boyd
T
T
Hünig
D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D005260:Female; D007376:Interleukin-2 / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis / Q000502:physiology; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; D016693:Receptors, Antigen, T-Cell, alpha-beta; D015375:Receptors, Interleukin-2