Targeted disruption of the MHC class II Aa gene in C57BL/6 mice.
The MHC class II gene Aa was disrupted by targeted mutation in embryonic stem (ES) cells derived from C57BL/6 mice to prevent expression of MHC class II molecules. Contrary to previous reports, the effect of the null-mutation on T cell development was investigated in C57BL/6 mice, which provide a defined genetic background. The complete lack of cell surface expression of MHC class II molecules in B6-Aa0/Aa0 homozygous mutant mice was directly demonstrated by cytofluorometric analysis using anti-Ab and anti-Ia specific mAbs. Development of CD4+CD8- T cells in the thymus was largely absent except for a small population of thymocytes expressing high levels of CD4 together with low amounts of CD8. The majority of these cells express the TCR at high density. Although mature CD4+CD8- T cells were undetectable in the thymus, some T cells with a CD4+CD8-TCRhigh phenotype were found in lymph nodes and spleen. Peripheral T cells from the mutant mice can be polyclonally activated in vitro with the mitogen concanavalin A. However, they could not be stimulated with staphylococcal enterotoxin B in autologous lymphocyte reactions, thereby demonstrating the absence of MHC class II expression in these mice. Peripheral B cells in B6-Aa0/Aa0 mutants were functional and responded to the T cell independent antigen levan by the production of antigen-specific IgM antibodies similar to wild-type cells. The B6-Aa0/Aa0 mutant mice described in this study represent an important tool to investigate the involvement of MHC class II molecules in lymphocyte maturation and the immune response.
Köntgen
F
F
Department of Biology, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
Süss
G
G
Stewart
C
C
Steinmetz
M
M
Bluethmann
H
H
D000818:Animals; D000955:Antigens, T-Independent / Q000276:immunology; D001483:Base Sequence; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D005260:Female; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D007114:Immunization; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*
D000955:Antigens, T-Independent; D015704:CD4 Antigens; D016827:CD8 Antigens; D000949:Histocompatibility Antigens Class II; D011948:Receptors, Antigen, T-Cell