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.
Department of Biology, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
F
F
Köntgen
G
G
Süss
C
C
Stewart
M
M
Steinmetz
H
H
Bluethmann
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