Positive regulation of human T cell activation by Gi2 proteins and interleukin-8.
We investigated whether pertussis toxin (PT)-sensitive heterotrimeric Gi proteins (Gi1, Gi2, Gi3) are involved in the regulation of TCR-induced activation of human T cells. First, Gi proteins were inactivated by PT: pretreatment with PT of purified blood T lymphocytes before CD3 cross-linking inhibited cell proliferation (-71.1 +/- 22.0%, P < 0.001), production of interleukin-2 (IL-2; -47.3 +/- 12.6%, P = 0.008), and expression of CD25 (-24.6 +/- 11.7%, P < 0.001) and CD69 (-25.7 +/- 9.0%, P < 0.001). Then, to identify which of the three Gi was involved, Gi1, Gi2, and Gi3 proteins were specifically inactivated by stably transfecting dominant-negative mutated forms of their alpha subunit in Jurkat cells. After activation, IL-2 production and CD69 expression were inhibited only in cells expressing inactive Gi2. We then studied the effects of interleukin-8 (IL-8), a CXC-chemokine with receptors coupled to Gi2 and produced in an autocrine fashion by activated T cells. Although its effects varied among donors, exogenous IL-8 stimulated proliferation and CD25 expression (up to, respectively, 200 and 77%) of PB T lymphocytes in response to CD3 activation, in a PT-sensitive manner. IL-8 also stimulated IL-2 production (by up to 42%) and CD69 expression, although weakly (+27%). Anti-human IL-8 antibody inhibited proliferation (-43%) and CD25 up-regulation (-45%) of activated T lymphocytes. In summary, several major responses of human T lymphocytes to TCR-mediated activation are regulated by Gi2 proteins, which for this function can be activated by IL-8 in an autocrine manner.
Lippert
E
E
INSERM U463 Interactions Récepteurs-Ligands en Immunologie et Cancérologie, Institut de Biologie, Nantes, France.
Jacques
Y
Y
Hermouet
S
S
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000502:physiology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis / Q000502:physiology; D002478:Cells, Cultured; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000494:pharmacology / Q000502:physiology*; D019169:Jurkat Cells; D037181:Lectins, C-Type; D008213:Lymphocyte Activation / Q000276:immunology*; D037342:Pertussis Toxin; D010835:Phytohemagglutinins / Q000494:pharmacology; D010940:Plant Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051381:Rats; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D007376:Interleukin-2; D016209:Interleukin-8; D037181:Lectins, C-Type; D037342:Pertussis Toxin; D010835:Phytohemagglutinins; D010940:Plant Proteins; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D010566:Virulence Factors, Bordetella; D000099192:CD69 Antigens; C101135:phytohemagglutinin L protein, Phaseolus vulgaris; C498015:GNAI2 protein, human; C498017:Gnai2 protein, rat