ABSTRACT
The T cell specific adapter protein (TSAd) is expressed in activated T cells and NK cells. While TSAd is beginning to emerge as a critical regulator of Lck and Itk activity in T cells, its role in NK cells has not yet been explored. Here we have examined susceptibility to virus infections in a murine model using various viral infection models. We report that TSAd-deficient mice display reduced clearance of murine cytomegalovirus (MCMV) that lack the viral MHC class I homologue m157, which is critical for Ly49H-mediated NK cell recognition of infected cells. In this infection model, NK cells contribute in the early stages of the disease, whereas CD8+ T cells are critical for viral clearance. We found that mice infected with MCMV Δm157 displayed reduced viral clearance in the spleen as well as reduced proliferation in spleen NK cells and CD8+ T cells in the absence of TSAd. Though no other immunophenotype was detected in the infection models tested, these data suggests that in the absence of the Ly49H ligand activation, NK cell and CD8+ T cell responses may be compromised in TSAd-deficient mice.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Muromegalovirus/genetics , Viral Proteins/genetics , Adaptor Proteins, Signal Transducing/genetics , Animals , CD11b Antigen/metabolism , CD8-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , Cell Line , Cell Proliferation , Cytomegalovirus Infections/immunology , Cytomegalovirus Infections/veterinary , Cytomegalovirus Infections/virology , Disease Models, Animal , Flow Cytometry , Genotype , Humans , Immunophenotyping , Killer Cells, Natural/cytology , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Muromegalovirus/physiology , Mutation , Spleen/cytology , Spleen/immunology , Spleen/virology , Tumor Necrosis Factor Receptor Superfamily, Member 7/metabolism , Viral Load , Virus ReplicationABSTRACT
The hallmark of the classical major histocompatibility complex (MHC) class I molecules is their astonishing level of polymorphism, a characteristic not shared by the nonclassical MHC class I genes. A distinct family of MHC class I genes has been recently identified within the human MHC class I region. The MICA (MHC class I chain-related A) gene in this family is a highly divergent member of the MHC class I family and has a unique pattern of tissue expression. We have sequenced exons encoding the extracellular alpha1, alpha2, and alpha3 domains of the MICA gene from twenty HLA homozygous typing cell lines and four unrelated individuals. We report the identification of eleven new alleles defined by a total of twenty-two amino acid substitutions. Thus, the total number of MICA alleles is sixteen. Interestingly, a tentative superimposition of MICA variable residues on the HLA-A2 structure reveals a unique pattern of distribution, concentrated primarily on the outer edge of the MICA putative antigen binding cleft, apparently bordering an invariant ligand binding site.
