From pathology to physiology of the human T-lymphocyte receptor.
The recent description of a selective human CD3 gamma deficiency and other T-cell receptor (TCR)/CD3 structural and functional defects, together with previous biochemical data on the structure and interactions of the TCR/CD3 complex, may aid in elucidating the physiology of this multi-subunit membrane ensemble. CD3 gamma seemed to be required for the commitment and thymic maturation of an important fraction of T lymphocytes to the CD8 (but not CD4) lineage, perhaps by participating with the CD8 co-receptor in the instructive signal delivered through the alpha beta TCR during intrathymic positive selection by HLA class I molecules. The homologous CD3 delta component would, in contrast, be necessary for the selection of CD4 lymphocytes by HLA class II molecules. The interaction of CD4 and CD8 with the TCR/CD3 complex during antigen recognition may thus be asymmetrical, taking place through CD3 delta and gamma, respectively. Also, the existence of in vivo functional TCR/CD3 hemireceptors (lacking either CD3 gamma or CD3 delta) is suggested, and defects in their relative amount on the T-cell surface may disrupt unresponsiveness to self antigens and generate autoimmunity.
Regueiro
J R
JR
Timón
M
M
Pérez-Aciego
P
P
Corell
A
A
Martín-Vílla
J M
JM
Rodríguez-Gallego
C
C
Góngora
R
R
Arnaiz-Villena
A
A
D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D015551:Autoimmunity / Q000276:immunology; D017252:CD3 Complex; D006801:Humans; D008962:Models, Theoretical; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology
D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell