Role of Ly-6A/E and T cell receptor-zeta for IL-2 production. Phosphatidylinositol-anchored Ly-6A/E antagonizes T cell receptor-mediated IL-2 production by a zeta-independent pathway.
Ly-6A/E molecules were originally implicated in regulation of T cell activation because anti-Ly-6A/E mAb induce IL-2 production. More recently we have shown that anti-Ly-6A/E also inhibits IL-2 production induced by anti-CD3. In the present study we used mutant and transfected cell lines that varied in expression of Ly-6A/E or TCR-zeta to test whether the positive and negative modulations of IL-2 production by anti-Ly-6A/E occur by distinct mechanisms. Anti-Ly-6A/E inhibited anti-CD3-induced IL-2 production for Ly-6E.1-transfected EL4J cells, but did not affect IL-2 production of the parental Ly-6A/E-negative EL4J cells. These results indicate that TCR-mediated IL-2 production can occur in the absence of Ly-6A/E expression and establish that anti-Ly-6A/E-induced inhibition of IL-2 production was the result of antibody binding to Ly-6A/E. As expected, MA5.8 (zeta-negative) or CT108 (zeta-truncated) variants of the 2B4.11 T cell hybridoma did not produce IL-2 when stimulated with anti-Thy-1 or anti-Ly-6A/E mAb. In contrast, anti-Ly-6A/E inhibited anti-CD3-induced IL-2 production by MA5.8 and CT108. Furthermore, anti-Ly-6A/E-induced IL-2 production was restored for zeta-transfected MA5.8. Thus, although induction of IL-2 by anti-Ly-6A/E depends on zeta expression, inhibition of IL-2 by anti-Ly-6A/E occurs by a zeta-independent mechanism. Interestingly, anti-Ly-6A/E, but not anti-Thy-1, inhibited anti-CD3-induced IL-2 production by MA5.8 and Ly-6E.1-transfected EL4J. Therefore, inhibition of IL-2 production by anti-Ly-6A/E was not a general property of a mAb binding to a phosphatidylinositol-linked molecule, as has been suggested for induction of IL-2 production. Taken together these data suggest that the molecular mechanisms of induction and inhibition of IL-2 production by anti-Ly-6A/E are separable and expression of TCR-zeta is one variable that distinguishes these two pathways.
Codias
E K
EK
Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101.
Fleming
T J
TJ
Zacharchuk
C M
CM
Ashwell
J D
JD
Malek
T R
TR
D000818:Animals; D000950:Antigens, Ly / Q000502:physiology*; D002478:Cells, Cultured; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000096:biosynthesis*; D051379:Mice; D010716:Phosphatidylinositols / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection
D000950:Antigens, Ly; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D007376:Interleukin-2; D010716:Phosphatidylinositols; D011948:Receptors, Antigen, T-Cell