Positive selection of V beta 8+ CD4-8- thymocytes by class I molecules expressed by hematopoietic cells.
A small subset of T cells of mature phenotype express the alpha/beta T cell receptor, but not CD4 and CD8 coreceptors (alpha/beta double-negative [DN] cells). The repertoire of V beta usage of alpha/beta DN cells is strongly biased towards V beta 8 expression, suggesting that the formation of the population is subject to selection. We now report that deficiency of class I expression leads to a strongly depressed frequency of V beta 8+ DN cells, but has little effect on V beta 8- DN cells. Studies of hematopoietic chimeras between class I+ and class I- mice demonstrated that expression of class I molecules by hematopoietic cells is necessary and sufficient for selection of most V beta 8 DN cells. The lack of a role for class I expression by thymic epithelial cells suggests that the mechanism of selection of these cells by class I differs significantly from the mechanism of selection of conventional T cells. Models to explain the selection of these cells as well as their possible function in vivo are discussed.
Bix
M
M
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Coles
M
M
Raulet
D
D
D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D008099:Liver / Q000196:embryology; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D011828:Radiation Chimera; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology*; D001613:beta 2-Microglobulin / Q000378:metabolism
D015704:CD4 Antigens; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D016693:Receptors, Antigen, T-Cell, alpha-beta; D001613:beta 2-Microglobulin