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Nonequivalence of classical MHC class I loci in ability to direct effective antiviral immunity.

Pavelko KD, Mendez-Fernandez Y, Bell MP, Hansen MJ, Johnson AJ, David CS, Rodriguez M, Pease LR - PLoS Pathog. (2012)

Bottom Line: We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens.Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity.This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA.

ABSTRACT
Structural diversity in the peptide binding sites of the redundant classical MHC antigen presenting molecules is strongly selected in humans and mice. Although the encoded antigen presenting molecules overlap in antigen presenting function, differences in polymorphism at the MHC I A, B and C loci in humans and higher primates indicate these loci are not functionally equivalent. The structural basis of these differences is not known. We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens. Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity. Whereas, parental FVB and transgenic FVB mice expressing the H-2K(b) gene are highly susceptible to persisting Theiler's virus infection within the CNS and subsequent demyelination, mice expressing the D(b) transgene clear the virus and are protected from demyelination. Remarkably, animals expressing a chimeric transgene, comprised primarily of K(b) but encoding the peptide binding domain of D(b), develop a robust anti viral CTL response yet fail to clear virus and develop significant demyelination. Differences in expression of the chimeric K(b)α1α2D(b) gene (low) and D(b) (high) in the CNS of infected mice mirror expression levels of their endogenous H-2(q) counterparts in FVB mice. These findings demonstrate that locus specific elements other than those specifying peptide binding and T cell receptor interaction can determine ability to clear virus infection. This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

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Surface expression of H-2 transgenes is regulated by genomic elements outside of sequences encoding peptide binding domains.(A) The mean fluorescence intensity (MFI) for peripheral blood lymphocytes stained with the H-2Db specific antibody B22.249 from H-2b haplotype mice (white) and transgenic mice (gray); (* Line 1 v. B10 or FVB Db, p<0.05, a Line 2 v. B10 or FVB Db, p<0.05). (B) Splenocytes from mice infected with TMEV for 21 days were isolated and tested by flow cytometry for H-2Db expression levels using B22.249.R1 labeled with FITC. Data are expressed as the MFI of the FITC labeled cells (* p<0.05, Two-way ANOVA). (C) The same splenocytes in (B) were co-stained with AF6-88.5 labeled phycoerythrin to determined expression of the H-2Kb present on the chimeric Kbα1α2Db molecule. Data are expressed as MFI of PE labeled cells (* p<0.001, Two-way ANOVA). (D) Brain resident cells from FVB, FVB Db and FVB Kbα1α2Db mice were isolated from naïve mice and analyzed by flow cytometry. Side-scatter and forward-scatter were analyzed for the presence of mononuclear resident cells using a lymphocyte gate. Resident antigen-presenting cells were further analyzed by a CD45 mid-level staining gate and assessed for expression of MHC class I. FVB (green), FVB Db (black) and FVB Kbα1α2Db (blue) brain cells were assessed for H-2Db expression by FACS (* p<0.001, t-test). (E) Brain cells isolated from 6 day TMEV infected mice were gated as in (D) and assessed for changes in H-2Db expression by FACS. Data are the MFI for H-2Db-FITC.
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ppat-1002541-g005: Surface expression of H-2 transgenes is regulated by genomic elements outside of sequences encoding peptide binding domains.(A) The mean fluorescence intensity (MFI) for peripheral blood lymphocytes stained with the H-2Db specific antibody B22.249 from H-2b haplotype mice (white) and transgenic mice (gray); (* Line 1 v. B10 or FVB Db, p<0.05, a Line 2 v. B10 or FVB Db, p<0.05). (B) Splenocytes from mice infected with TMEV for 21 days were isolated and tested by flow cytometry for H-2Db expression levels using B22.249.R1 labeled with FITC. Data are expressed as the MFI of the FITC labeled cells (* p<0.05, Two-way ANOVA). (C) The same splenocytes in (B) were co-stained with AF6-88.5 labeled phycoerythrin to determined expression of the H-2Kb present on the chimeric Kbα1α2Db molecule. Data are expressed as MFI of PE labeled cells (* p<0.001, Two-way ANOVA). (D) Brain resident cells from FVB, FVB Db and FVB Kbα1α2Db mice were isolated from naïve mice and analyzed by flow cytometry. Side-scatter and forward-scatter were analyzed for the presence of mononuclear resident cells using a lymphocyte gate. Resident antigen-presenting cells were further analyzed by a CD45 mid-level staining gate and assessed for expression of MHC class I. FVB (green), FVB Db (black) and FVB Kbα1α2Db (blue) brain cells were assessed for H-2Db expression by FACS (* p<0.001, t-test). (E) Brain cells isolated from 6 day TMEV infected mice were gated as in (D) and assessed for changes in H-2Db expression by FACS. Data are the MFI for H-2Db-FITC.

Mentions: Next, we assessed the expression of the transgene and endogenously encoded class I genes at the protein level. The mean fluorescence intensity of class I molecules expressing the B22.249 (Db) defined epitope shared by Db and Kbα1α2Db was comparable in peripheral blood mononuclear cells for all the tested mouse lines, although a slight, but statistically significant lower expression was seen for the chimeric transgene encoded molecules (Figure 5A). A similar expression pattern was seen using spleen cells when comparing independent founder lines (Figure 5B). Expression of the Kbα1α2Db transgene was confirmed in these mice by using an antibody [23] with a reactivity pattern dependent, in part, on the α3 region of Kb (Figure 5C).


Nonequivalence of classical MHC class I loci in ability to direct effective antiviral immunity.

Pavelko KD, Mendez-Fernandez Y, Bell MP, Hansen MJ, Johnson AJ, David CS, Rodriguez M, Pease LR - PLoS Pathog. (2012)

Surface expression of H-2 transgenes is regulated by genomic elements outside of sequences encoding peptide binding domains.(A) The mean fluorescence intensity (MFI) for peripheral blood lymphocytes stained with the H-2Db specific antibody B22.249 from H-2b haplotype mice (white) and transgenic mice (gray); (* Line 1 v. B10 or FVB Db, p<0.05, a Line 2 v. B10 or FVB Db, p<0.05). (B) Splenocytes from mice infected with TMEV for 21 days were isolated and tested by flow cytometry for H-2Db expression levels using B22.249.R1 labeled with FITC. Data are expressed as the MFI of the FITC labeled cells (* p<0.05, Two-way ANOVA). (C) The same splenocytes in (B) were co-stained with AF6-88.5 labeled phycoerythrin to determined expression of the H-2Kb present on the chimeric Kbα1α2Db molecule. Data are expressed as MFI of PE labeled cells (* p<0.001, Two-way ANOVA). (D) Brain resident cells from FVB, FVB Db and FVB Kbα1α2Db mice were isolated from naïve mice and analyzed by flow cytometry. Side-scatter and forward-scatter were analyzed for the presence of mononuclear resident cells using a lymphocyte gate. Resident antigen-presenting cells were further analyzed by a CD45 mid-level staining gate and assessed for expression of MHC class I. FVB (green), FVB Db (black) and FVB Kbα1α2Db (blue) brain cells were assessed for H-2Db expression by FACS (* p<0.001, t-test). (E) Brain cells isolated from 6 day TMEV infected mice were gated as in (D) and assessed for changes in H-2Db expression by FACS. Data are the MFI for H-2Db-FITC.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285594&req=5

ppat-1002541-g005: Surface expression of H-2 transgenes is regulated by genomic elements outside of sequences encoding peptide binding domains.(A) The mean fluorescence intensity (MFI) for peripheral blood lymphocytes stained with the H-2Db specific antibody B22.249 from H-2b haplotype mice (white) and transgenic mice (gray); (* Line 1 v. B10 or FVB Db, p<0.05, a Line 2 v. B10 or FVB Db, p<0.05). (B) Splenocytes from mice infected with TMEV for 21 days were isolated and tested by flow cytometry for H-2Db expression levels using B22.249.R1 labeled with FITC. Data are expressed as the MFI of the FITC labeled cells (* p<0.05, Two-way ANOVA). (C) The same splenocytes in (B) were co-stained with AF6-88.5 labeled phycoerythrin to determined expression of the H-2Kb present on the chimeric Kbα1α2Db molecule. Data are expressed as MFI of PE labeled cells (* p<0.001, Two-way ANOVA). (D) Brain resident cells from FVB, FVB Db and FVB Kbα1α2Db mice were isolated from naïve mice and analyzed by flow cytometry. Side-scatter and forward-scatter were analyzed for the presence of mononuclear resident cells using a lymphocyte gate. Resident antigen-presenting cells were further analyzed by a CD45 mid-level staining gate and assessed for expression of MHC class I. FVB (green), FVB Db (black) and FVB Kbα1α2Db (blue) brain cells were assessed for H-2Db expression by FACS (* p<0.001, t-test). (E) Brain cells isolated from 6 day TMEV infected mice were gated as in (D) and assessed for changes in H-2Db expression by FACS. Data are the MFI for H-2Db-FITC.
Mentions: Next, we assessed the expression of the transgene and endogenously encoded class I genes at the protein level. The mean fluorescence intensity of class I molecules expressing the B22.249 (Db) defined epitope shared by Db and Kbα1α2Db was comparable in peripheral blood mononuclear cells for all the tested mouse lines, although a slight, but statistically significant lower expression was seen for the chimeric transgene encoded molecules (Figure 5A). A similar expression pattern was seen using spleen cells when comparing independent founder lines (Figure 5B). Expression of the Kbα1α2Db transgene was confirmed in these mice by using an antibody [23] with a reactivity pattern dependent, in part, on the α3 region of Kb (Figure 5C).

Bottom Line: We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens.Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity.This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA.

ABSTRACT
Structural diversity in the peptide binding sites of the redundant classical MHC antigen presenting molecules is strongly selected in humans and mice. Although the encoded antigen presenting molecules overlap in antigen presenting function, differences in polymorphism at the MHC I A, B and C loci in humans and higher primates indicate these loci are not functionally equivalent. The structural basis of these differences is not known. We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens. Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity. Whereas, parental FVB and transgenic FVB mice expressing the H-2K(b) gene are highly susceptible to persisting Theiler's virus infection within the CNS and subsequent demyelination, mice expressing the D(b) transgene clear the virus and are protected from demyelination. Remarkably, animals expressing a chimeric transgene, comprised primarily of K(b) but encoding the peptide binding domain of D(b), develop a robust anti viral CTL response yet fail to clear virus and develop significant demyelination. Differences in expression of the chimeric K(b)α1α2D(b) gene (low) and D(b) (high) in the CNS of infected mice mirror expression levels of their endogenous H-2(q) counterparts in FVB mice. These findings demonstrate that locus specific elements other than those specifying peptide binding and T cell receptor interaction can determine ability to clear virus infection. This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

Show MeSH
Related in: MedlinePlus