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Human CD3γ, but not CD3δ, haploinsufficiency differentially impairs γδ versus αβ surface TCR expression.

Muñoz-Ruiz M, Pérez-Flores V, Garcillán B, Guardo AC, Mazariegos MS, Takada H, Allende LM, Kilic SS, Sanal O, Roifman CM, López-Granados E, Recio MJ, Martínez-Naves E, Fernández-Malavé E, Regueiro JR - BMC Immunol. (2013)

Bottom Line: To test this hypothesis, we compared the surface TCR expression of primary αβ and γδ T cells from healthy donors carrying a single or leaky mutation in CD3G (γ+/-) or CD3D (δ+/-, δ+/leaky) with that of normal controls.Although the partial reduction in the intracellular availability of CD3γ or CD3δ proteins was comparable as a consequence of the mutations, surface TCR expression measured with anti-CD3ε antibodies was significantly more decreased in γδ than in αβ T lymphocytes in CD3γ+/- individuals, whereas CD3δ+/- and CD3δ+/leaky donors showed a similar decrease of surface TCR in both T cell lineages.A modified version of the prevailing TCR assembly model is proposed to accommodate these new data.

View Article: PubMed Central - HTML - PubMed

Affiliation: Inmunología, Facultad de Medicina, Universidad Complutense, Madrid, 28040, Spain.

ABSTRACT

Background: The T cell antigen receptors (TCR) of αβ and γδ T lymphocytes are believed to assemble in a similar fashion in humans. Firstly, αβ or γδ TCR chains incorporate a CD3δε dimer, then a CD3γε dimer and finally a ζζ homodimer, resulting in TCR complexes with the same CD3 dimer stoichiometry. Partial reduction in the expression of the highly homologous CD3γ and CD3δ proteins would thus be expected to have a similar impact in the assembly and surface expression of both TCR isotypes. To test this hypothesis, we compared the surface TCR expression of primary αβ and γδ T cells from healthy donors carrying a single or leaky mutation in CD3G (γ+/-) or CD3D (δ+/-, δ+/leaky) with that of normal controls.

Results: Although the partial reduction in the intracellular availability of CD3γ or CD3δ proteins was comparable as a consequence of the mutations, surface TCR expression measured with anti-CD3ε antibodies was significantly more decreased in γδ than in αβ T lymphocytes in CD3γ+/- individuals, whereas CD3δ+/- and CD3δ+/leaky donors showed a similar decrease of surface TCR in both T cell lineages. Therefore, surface γδ TCR expression was more dependent on available CD3γ than surface αβ TCR expression.

Conclusions: The results support the existence of differential structural constraints in the two human TCR isotypes regarding the incorporation of CD3γε and CD3δε dimers, as revealed by their discordant surface expression behaviour when confronted with reduced amounts of CD3γ, but not of the homologous CD3δ chain. A modified version of the prevailing TCR assembly model is proposed to accommodate these new data.

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Peripheral αβ and γδ T lymphocyte numbers in human CD3G or CD3D haploinsufficiencies. (A) Peripheral blood cell counts from different γ+/−, δ+/− or δ+/leaky individuals are compared with the normal age-matched distribution as mean ± SEM against the P5/P95 normal range (horizontal dashed lines [6]). Asterisks in bars indicate significant differences as compared with controls. p < *0.05, **0.01 or ***0.001. (B) Proportion of αβ (BMA031+) and γδ (Immu510+) T cells (defined as CD3+) in different peripheral blood subsets (CD4+, CD8bright, CD8dull and DN) in healthy individuals. Data are mean ± SD (n = 6).
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Figure 1: Peripheral αβ and γδ T lymphocyte numbers in human CD3G or CD3D haploinsufficiencies. (A) Peripheral blood cell counts from different γ+/−, δ+/− or δ+/leaky individuals are compared with the normal age-matched distribution as mean ± SEM against the P5/P95 normal range (horizontal dashed lines [6]). Asterisks in bars indicate significant differences as compared with controls. p < *0.05, **0.01 or ***0.001. (B) Proportion of αβ (BMA031+) and γδ (Immu510+) T cells (defined as CD3+) in different peripheral blood subsets (CD4+, CD8bright, CD8dull and DN) in healthy individuals. Data are mean ± SD (n = 6).

Mentions: CD3G (γ+/−) or CD3D (δ+/−) haploinsufficient donors were uniformly healthy and showed abundant peripheral blood T lymphocytes with an essentially normal phenotype (Table 1). However, total T cell numbers were consistently lower than controls (Figure 1A) which correlated with a partial impairment of lymphocyte function (Table 1).


Human CD3γ, but not CD3δ, haploinsufficiency differentially impairs γδ versus αβ surface TCR expression.

Muñoz-Ruiz M, Pérez-Flores V, Garcillán B, Guardo AC, Mazariegos MS, Takada H, Allende LM, Kilic SS, Sanal O, Roifman CM, López-Granados E, Recio MJ, Martínez-Naves E, Fernández-Malavé E, Regueiro JR - BMC Immunol. (2013)

Peripheral αβ and γδ T lymphocyte numbers in human CD3G or CD3D haploinsufficiencies. (A) Peripheral blood cell counts from different γ+/−, δ+/− or δ+/leaky individuals are compared with the normal age-matched distribution as mean ± SEM against the P5/P95 normal range (horizontal dashed lines [6]). Asterisks in bars indicate significant differences as compared with controls. p < *0.05, **0.01 or ***0.001. (B) Proportion of αβ (BMA031+) and γδ (Immu510+) T cells (defined as CD3+) in different peripheral blood subsets (CD4+, CD8bright, CD8dull and DN) in healthy individuals. Data are mean ± SD (n = 6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585704&req=5

Figure 1: Peripheral αβ and γδ T lymphocyte numbers in human CD3G or CD3D haploinsufficiencies. (A) Peripheral blood cell counts from different γ+/−, δ+/− or δ+/leaky individuals are compared with the normal age-matched distribution as mean ± SEM against the P5/P95 normal range (horizontal dashed lines [6]). Asterisks in bars indicate significant differences as compared with controls. p < *0.05, **0.01 or ***0.001. (B) Proportion of αβ (BMA031+) and γδ (Immu510+) T cells (defined as CD3+) in different peripheral blood subsets (CD4+, CD8bright, CD8dull and DN) in healthy individuals. Data are mean ± SD (n = 6).
Mentions: CD3G (γ+/−) or CD3D (δ+/−) haploinsufficient donors were uniformly healthy and showed abundant peripheral blood T lymphocytes with an essentially normal phenotype (Table 1). However, total T cell numbers were consistently lower than controls (Figure 1A) which correlated with a partial impairment of lymphocyte function (Table 1).

Bottom Line: To test this hypothesis, we compared the surface TCR expression of primary αβ and γδ T cells from healthy donors carrying a single or leaky mutation in CD3G (γ+/-) or CD3D (δ+/-, δ+/leaky) with that of normal controls.Although the partial reduction in the intracellular availability of CD3γ or CD3δ proteins was comparable as a consequence of the mutations, surface TCR expression measured with anti-CD3ε antibodies was significantly more decreased in γδ than in αβ T lymphocytes in CD3γ+/- individuals, whereas CD3δ+/- and CD3δ+/leaky donors showed a similar decrease of surface TCR in both T cell lineages.A modified version of the prevailing TCR assembly model is proposed to accommodate these new data.

View Article: PubMed Central - HTML - PubMed

Affiliation: Inmunología, Facultad de Medicina, Universidad Complutense, Madrid, 28040, Spain.

ABSTRACT

Background: The T cell antigen receptors (TCR) of αβ and γδ T lymphocytes are believed to assemble in a similar fashion in humans. Firstly, αβ or γδ TCR chains incorporate a CD3δε dimer, then a CD3γε dimer and finally a ζζ homodimer, resulting in TCR complexes with the same CD3 dimer stoichiometry. Partial reduction in the expression of the highly homologous CD3γ and CD3δ proteins would thus be expected to have a similar impact in the assembly and surface expression of both TCR isotypes. To test this hypothesis, we compared the surface TCR expression of primary αβ and γδ T cells from healthy donors carrying a single or leaky mutation in CD3G (γ+/-) or CD3D (δ+/-, δ+/leaky) with that of normal controls.

Results: Although the partial reduction in the intracellular availability of CD3γ or CD3δ proteins was comparable as a consequence of the mutations, surface TCR expression measured with anti-CD3ε antibodies was significantly more decreased in γδ than in αβ T lymphocytes in CD3γ+/- individuals, whereas CD3δ+/- and CD3δ+/leaky donors showed a similar decrease of surface TCR in both T cell lineages. Therefore, surface γδ TCR expression was more dependent on available CD3γ than surface αβ TCR expression.

Conclusions: The results support the existence of differential structural constraints in the two human TCR isotypes regarding the incorporation of CD3γε and CD3δε dimers, as revealed by their discordant surface expression behaviour when confronted with reduced amounts of CD3γ, but not of the homologous CD3δ chain. A modified version of the prevailing TCR assembly model is proposed to accommodate these new data.

Show MeSH
Related in: MedlinePlus