Memory CD8 T lymphocytes express inhibitory MHC-specific Ly49 receptors.
Natural killer (NK) cells survey potential targets using an array of receptors specific for major histocompatibility complex class I molecules. In mice, members of the Ly49 receptor gene family are expressed on overlapping subsets of NK cells and on CD1-restricted NK1 T cells. Here we characterize a population of memory cytotoxic (CD8(+)) T lymphocytes which also express inhibitory Ly49 family members. This cell population increases steadily with age; by 11 months, over one third of memory CD8(+) T cells express Ly49 molecules. These cells appear to express a normal TCR repertoire, and share several traits with previously activated T cells. Analysis of mutant mouse strains reveals that normal development of these cells depends upon the presence of the transporter associated with antigen presentation (TAP), classical class I molecules, and class II molecules. As a functional consequence of Ly49 expression, we demonstrate that T cell receptor-mediated activation of CD8(+) T cells is inhibited by Ly49 interactions with cognate class I molecules. We hypothesize that conventional memory CD8(+) T cells initiate Ly49 expression as a means of dampening an immune response and / or inhibiting T cell autoreactivity.
Coles
M C
MC
Department of Molecular Biology, Cancer Research Laboratory, University of California at Berkeley, Berkely, USA.
McMahon
C W
CW
Takizawa
H
H
Raulet
D H
DH
D000367:Age Factors; D000818:Animals; D000950:Antigens, Ly; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry* / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000502:physiology*; D007156:Immunologic Memory; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D011971:Receptors, Immunologic / Q000032:analysis*; D055630:Receptors, NK Cell Lectin-Like
D000950:Antigens, Ly; D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011971:Receptors, Immunologic; D055630:Receptors, NK Cell Lectin-Like