Biochemical Differences in the αβ T Cell Receptor·CD3 Surface Complex between CD8+ and CD4+ Human Mature T Lymphocytes

Pilar S. Torres,María L. Toribio,David A. Zapata,Balbino Alarcón,María N. Navarro,José R. Regueiro,Wolfgang W.A. Schamel,Nineth E. Rossi

doi:10.1074/jbc.m311455200

Abstract

We have reported the existence of biochemical and conformational differences in the alphabeta T cell receptor (TCR) complex between CD4(+) and CD8(+) CD3gamma-deficient (gamma(-)) mature T cells. In the present study, we have furthered our understanding and extended the observations to primary T lymphocytes from normal (gamma(+)) individuals. Surface TCR.CD3 components from CD4(+) gamma(-) T cells, other than CD3gamma, were detectable and similar in size to CD4(+) gamma(+) controls. Their native TCR.CD3 complex was also similar to CD4(+) gamma(+) controls, except for an alphabeta(deltaepsilon)(2)zeta(2) instead of an alphabetagammaepsilondeltaepsilonzeta(2) stoichiometry. In contrast, the surface TCRalpha, TCRbeta, and CD3delta chains of CD8(+) gamma(-) T cells did not possess their usual sizes. Using confocal immunofluorescence, TCRalpha was hardly detectable in CD8(+) gamma(-) T cells. Blue native gels (BN-PAGE) demonstrated the existence of a heterogeneous population of TCR.CD3 in these cells. Using primary peripheral blood T lymphocytes from normal (gamma(+)) donors, we performed a broad epitopic scan. In contrast to all other TCR.CD3-specific monoclonal antibodies, RW2-8C8 stained CD8(+) better than it did CD4(+) T cells, and the difference was dependent on glycosylation of the TCR.CD3 complex but independent of T cell activation or differentiation. RW2-8C8 staining of CD8(+) T cells was shown to be more dependent on lipid raft integrity than that of CD4(+) T cells. Finally, immunoprecipitation studies on purified primary CD4(+) and CD8(+) T cells revealed the existence of TCR glycosylation differences between the two. Collectively, these results are consistent with the existence of conformational or topological lineage-specific differences in the TCR.CD3 from CD4(+) and CD8(+) wild type T cells. The differences may be relevant for cis interactions during antigen recognition and signal transduction.

Highlights

Mature CD4ϩ and CD8ϩ ␣␤ T cells differ sharply in their major histocompatibility complex ligands, but their TCR1⁄7CD3 complex is believed to be qualitatively identical
We have extended these biochemical studies to the cell surface and provide further evidence for the existence of qualitative differences in the ␣␤ TCR1⁄7CD3 complex between CD8ϩ and CD4ϩ T lymphocytes, when CD3␥ is lacking, and in normal T cells
The results indicated that the TCR1⁄7CD3 complex from CD4ϩ ␥Ϫ T lymphocytes was similar to normal complexes from ␥ϩ T cells (CD4ϩ, CD8ϩ, or Jurkat), with delayed electrophoretic mobility (Fig. 4A)

Summary

Introduction

Mature CD4ϩ and CD8ϩ ␣␤ T cells differ sharply in their major histocompatibility complex ligands, but their TCR1⁄7CD3 complex is believed to be qualitatively identical. We have extended these biochemical studies to the cell surface and provide further evidence for the existence of qualitative differences in the ␣␤ TCR1⁄7CD3 complex between CD8ϩ and CD4ϩ T lymphocytes, when CD3␥ is lacking, and in normal T cells.

Results

Conclusion