Expression of functional CD8alpha Beta heterodimer on rat gamma delta T cells does not correlate with the CDR3 length of the TCR delta chain predicted for MHC class I-restricted antigen recognition.
In accordance with their lack of MHC restriction, most mouse and human gamma delta T cells express neither the CD4 nor CD8(alpha beta) coreceptor. In striking contrast, up to 80% of splenic rat gamma delta T cells express the CD8alpha beta isoform of CD8, which for the alpha beta T cell subset serves as a marker for MHC class I-restricted cells. We compared CD8 on alpha beta and gamma delta T cells with regard to co-stimulatory function and correlation of CD8 expression with TCRDV usage and CDR3delta length. In both subsets, CD8 acted as a co-stimulatory molecule in vitro and was found to bind the kinase lck efficiently. No differences between the CDR3delta length spectra of CD8+ and CD8- gamma delta T cells or between unselected thymic and peripheral gamma delta T cells were found. As seen in man and mice, CDR3delta were rather long, a structural feature which can be expected to interfere with an alpha beta TCR-like mode of MHC class I binding. In summary, CD8 expressed by rat gamma delta T cells is a molecule with the potential to act as a coreceptor, but its expression gives no indication for antigen recognition analogous to that of MHC class I-restricted alpha beta T cells.
Straube
F
F
Institute for Virology and Immunbiology, W¿rzburg, Germany.
Herrmann
T
T
D000818:Animals; D001483:Base Sequence; D016827:CD8 Antigens / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D022801:Complementarity Determining Regions / Q000737:chemistry*; D019281:Dimerization; D015395:Histocompatibility Antigens Class I / Q000502:physiology*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D051381:Rats; D011917:Rats, Inbred Lew; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*
D016827:CD8 Antigens; D022801:Complementarity Determining Regions; D015395:Histocompatibility Antigens Class I; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)