Differential modulation of CD8beta by rat gammadelta and alphabeta T cells after activation.
Major histocompatibility complex (MHC) class I-restricted alphabeta T cells express the CD8alphabeta heterodimer, which acts as a MHC class I-specific co-receptor. Rats are so far the only species with frequent expression of the CD8alphabeta by MHC-unrestricted gammadelta T cells. This study compares CD8alphabeta expression by splenic rat alphabeta and gammadelta T cells and reveals a lineage-specific difference in the control of CD8beta expression. After activation in vitro, many gammadelta T cells, but not alphabeta T cells, persistently down-modulate the expression of CD8beta, but not CD8alpha, at the RNA level. Down-regulation occurred after stimulation with T-cell receptor (TCR)-specific monoclonal antibody (mAb) and interleukin-2 (IL-2) or CD28-mediated costimulation, and after activation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. Functional differences between modulating and non-modulating cells were not found with respect to interferon-gamma (IFN-gamma) production and cytolytic activity. The modulation could be indicative for a fundamental difference between alphabeta and gammadelta T cells and also limits the use of CD8beta as a stable marker of gammadelta T-cell subsets. Possibly, CD8beta modulation provides a mechanism to escape over-stimulation by (auto-)antigens by increasing the threshold of TCR-mediated activation in gammadelta T cells.
Straube
F
F
Institute of Virology and Immunobiology, University of Würzburg, Würzburg, Germany.
Herrmann
T
T
D000818:Animals; D016827:CD8 Antigens / Q000235:genetics / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018929:Cell Culture Techniques; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation / Q000276:immunology; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000276:immunology
D016827:CD8 Antigens; C409469:CD8 antigen, alpha chain; C433839:CD8alphabeta antigen; D012333:RNA, Messenger; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D007371:Interferon-gamma