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The CD8 population in CD4-deficient mice is heavily contaminated with MHC class II-restricted T cells.

Tyznik AJ, Sun JC, Bevan MJ - J. Exp. Med. (2004)

Bottom Line: In experiments to study the impact of deficiency in CD4+ T cell help on the magnitude of CD8+ cytotoxic T cell response to pathogens, it was noted that in CD4 gene knockout mice, the CD8 population made significant responses to several nominally major histocompatibility complex (MHC) class II-restricted epitopes in addition to the expected responses to MHC class I-restricted epitopes.Further experiments suggested that these two observations are linked and that the CD8 population in CD4-/- mice may contain a majority of T cells that were actually selected by recognition of MHC class II molecules in the thymus.These results have implications for understanding CD4 versus CD8 lineage commitment in the thymus, and for the practical use of CD4-/- mice as models of helper deficiency.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, University of Washington, Seattle 98195, USA.

ABSTRACT
In experiments to study the impact of deficiency in CD4+ T cell help on the magnitude of CD8+ cytotoxic T cell response to pathogens, it was noted that in CD4 gene knockout mice, the CD8 population made significant responses to several nominally major histocompatibility complex (MHC) class II-restricted epitopes in addition to the expected responses to MHC class I-restricted epitopes. A similar response by CD8+ T cells to class II-restricted epitopes was not observed in wild-type mice, or in mice that had been acutely depleted of CD4+ T cells just before the immunization. Coincident with this unexpected response to class II-restricted epitopes, it was also observed that the CD8+ response to the class I-restricted epitopes was consistently lower in CD4-/- mice than in wild-type mice. Further experiments suggested that these two observations are linked and that the CD8 population in CD4-/- mice may contain a majority of T cells that were actually selected by recognition of MHC class II molecules in the thymus. These results have implications for understanding CD4 versus CD8 lineage commitment in the thymus, and for the practical use of CD4-/- mice as models of helper deficiency.

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Wild-type CD8+ T cells respond better than CD4−/− CD8+ T cells even when immunized in the same host. MACS-sorted CD8+ cells from Ly5.1 B6 and Ly5.2 CD4−/− mice were mixed in a 1:1 ratio and injected into Thy 1.1 hosts, which were immunized 1 d later with rLmOva or LCMV. For the analysis, donor T cells were gated as CD8+Thy1.1− and assessed for CD4−/− (Ly5.1−) or wild-type (Ly5.1+) origin. (A) 7 d after rLmOva immunization, the fraction of donor CD8+ T cells making IFN-γ in response to Ova peptide was quantitated. Numbers show the average of five adoptive hosts. (B) 8 d after LCMV immunization, IFN-γ synthesis by donor CD8 cells after in vitro stimulation with H2-Db-restricted GP33–41 peptide was assessed. Data are representative of two independent experiments.
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fig5: Wild-type CD8+ T cells respond better than CD4−/− CD8+ T cells even when immunized in the same host. MACS-sorted CD8+ cells from Ly5.1 B6 and Ly5.2 CD4−/− mice were mixed in a 1:1 ratio and injected into Thy 1.1 hosts, which were immunized 1 d later with rLmOva or LCMV. For the analysis, donor T cells were gated as CD8+Thy1.1− and assessed for CD4−/− (Ly5.1−) or wild-type (Ly5.1+) origin. (A) 7 d after rLmOva immunization, the fraction of donor CD8+ T cells making IFN-γ in response to Ova peptide was quantitated. Numbers show the average of five adoptive hosts. (B) 8 d after LCMV immunization, IFN-γ synthesis by donor CD8 cells after in vitro stimulation with H2-Db-restricted GP33–41 peptide was assessed. Data are representative of two independent experiments.

Mentions: As aforementioned, we observed that the overall magnitude of the CD8+ T cell response to class I–restricted peptides assessed by intracellular cytokine staining or cytotoxicity was consistently lower in CD4−/− than in wild-type mice (Figs. 1 and 2). To determine whether this was due to helper deficiency in the CD4−/− mice, or is an intrinsic property of the CD8 population, purified CD8+ T cells from wild-type and CD4−/− mice were mixed in a 1:1 ratio, transferred into adoptive hosts and immunized with pathogen. After immunization with rLmOva, the IFN-γ response of transferred wild-type CD8+ T cells to the Ova peptide was roughly twofold higher than the response of the transferred CD4−/− cells in the same infected host (Fig. 5 A). After correcting for the slight skewing of total donor CD8 T cell numbers after L. monocytogenes infection, there were 2.5-fold more wild-type than CD4−/− effectors.


The CD8 population in CD4-deficient mice is heavily contaminated with MHC class II-restricted T cells.

Tyznik AJ, Sun JC, Bevan MJ - J. Exp. Med. (2004)

Wild-type CD8+ T cells respond better than CD4−/− CD8+ T cells even when immunized in the same host. MACS-sorted CD8+ cells from Ly5.1 B6 and Ly5.2 CD4−/− mice were mixed in a 1:1 ratio and injected into Thy 1.1 hosts, which were immunized 1 d later with rLmOva or LCMV. For the analysis, donor T cells were gated as CD8+Thy1.1− and assessed for CD4−/− (Ly5.1−) or wild-type (Ly5.1+) origin. (A) 7 d after rLmOva immunization, the fraction of donor CD8+ T cells making IFN-γ in response to Ova peptide was quantitated. Numbers show the average of five adoptive hosts. (B) 8 d after LCMV immunization, IFN-γ synthesis by donor CD8 cells after in vitro stimulation with H2-Db-restricted GP33–41 peptide was assessed. Data are representative of two independent experiments.
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Related In: Results  -  Collection

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fig5: Wild-type CD8+ T cells respond better than CD4−/− CD8+ T cells even when immunized in the same host. MACS-sorted CD8+ cells from Ly5.1 B6 and Ly5.2 CD4−/− mice were mixed in a 1:1 ratio and injected into Thy 1.1 hosts, which were immunized 1 d later with rLmOva or LCMV. For the analysis, donor T cells were gated as CD8+Thy1.1− and assessed for CD4−/− (Ly5.1−) or wild-type (Ly5.1+) origin. (A) 7 d after rLmOva immunization, the fraction of donor CD8+ T cells making IFN-γ in response to Ova peptide was quantitated. Numbers show the average of five adoptive hosts. (B) 8 d after LCMV immunization, IFN-γ synthesis by donor CD8 cells after in vitro stimulation with H2-Db-restricted GP33–41 peptide was assessed. Data are representative of two independent experiments.
Mentions: As aforementioned, we observed that the overall magnitude of the CD8+ T cell response to class I–restricted peptides assessed by intracellular cytokine staining or cytotoxicity was consistently lower in CD4−/− than in wild-type mice (Figs. 1 and 2). To determine whether this was due to helper deficiency in the CD4−/− mice, or is an intrinsic property of the CD8 population, purified CD8+ T cells from wild-type and CD4−/− mice were mixed in a 1:1 ratio, transferred into adoptive hosts and immunized with pathogen. After immunization with rLmOva, the IFN-γ response of transferred wild-type CD8+ T cells to the Ova peptide was roughly twofold higher than the response of the transferred CD4−/− cells in the same infected host (Fig. 5 A). After correcting for the slight skewing of total donor CD8 T cell numbers after L. monocytogenes infection, there were 2.5-fold more wild-type than CD4−/− effectors.

Bottom Line: In experiments to study the impact of deficiency in CD4+ T cell help on the magnitude of CD8+ cytotoxic T cell response to pathogens, it was noted that in CD4 gene knockout mice, the CD8 population made significant responses to several nominally major histocompatibility complex (MHC) class II-restricted epitopes in addition to the expected responses to MHC class I-restricted epitopes.Further experiments suggested that these two observations are linked and that the CD8 population in CD4-/- mice may contain a majority of T cells that were actually selected by recognition of MHC class II molecules in the thymus.These results have implications for understanding CD4 versus CD8 lineage commitment in the thymus, and for the practical use of CD4-/- mice as models of helper deficiency.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, University of Washington, Seattle 98195, USA.

ABSTRACT
In experiments to study the impact of deficiency in CD4+ T cell help on the magnitude of CD8+ cytotoxic T cell response to pathogens, it was noted that in CD4 gene knockout mice, the CD8 population made significant responses to several nominally major histocompatibility complex (MHC) class II-restricted epitopes in addition to the expected responses to MHC class I-restricted epitopes. A similar response by CD8+ T cells to class II-restricted epitopes was not observed in wild-type mice, or in mice that had been acutely depleted of CD4+ T cells just before the immunization. Coincident with this unexpected response to class II-restricted epitopes, it was also observed that the CD8+ response to the class I-restricted epitopes was consistently lower in CD4-/- mice than in wild-type mice. Further experiments suggested that these two observations are linked and that the CD8 population in CD4-/- mice may contain a majority of T cells that were actually selected by recognition of MHC class II molecules in the thymus. These results have implications for understanding CD4 versus CD8 lineage commitment in the thymus, and for the practical use of CD4-/- mice as models of helper deficiency.

Show MeSH