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Itk negatively regulates induction of T cell proliferation by CD28 costimulation.

Liao XC, Fournier S, Killeen N, Weiss A, Allison JP, Littman DR - J. Exp. Med. (1997)

Bottom Line: T cells defective in Itk were found to be fully competent to respond to costimulation.The results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways.By negatively regulating the amplitude of signaling upon CD28 costimulation, Itk may provide a means for modulating the outcome of T cell activation during development and during antigen-driven immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA.

ABSTRACT
CD28 is a cell surface molecule that mediates a costimulatory signal crucial for T cell proliferation and lymphokine production. The signal transduction mechanisms of CD28 are not well understood. Itk, a nonreceptor protein tyrosine kinase specifically expressed in T cells and mast cells, has been implicated in the CD28 signaling pathway because of reports that it becomes phosphorylated on tyrosines and associates with CD28 upon cross-linking of the cell surface molecule. To determine whether Itk plays a functional role in CD28 signaling, we compared T cells from Itk-deficient mice and control mice for their responses to CD28 costimulation. T cells defective in Itk were found to be fully competent to respond to costimulation. Whereas the CD3-mediated proliferative response was severely compromised in the absence of Itk, the calcineurin-independent CD28-mediated response was significantly elevated when compared with cells from control animals. The augmented proliferation was not due to increased production of interleukin-2. The results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways. By negatively regulating the amplitude of signaling upon CD28 costimulation, Itk may provide a means for modulating the outcome of T cell activation during development and during antigen-driven immune responses.

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Related in: MedlinePlus

Cell proliferation induced by  TCR and CD28 is dependent on IL-2.  CD4+ T cells from itk−/− mice and itk+/−  littermates were stimulated with plate-bound  anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). Anti-CD28 and anti-murine IL-2 were added with anti-murine  IL-2R or with recombinant human IL-2 at  the beginning of culture. Cell proliferation  was measured 72 h after stimulation.  a-CD28, anti-CD28 ascites; a-mIL2, anti-murine IL-2 mAb; a-mIL2R, anti-murine  IL-2Rα mAb; and hIL-2, recombinant human IL-2.
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Figure 4: Cell proliferation induced by TCR and CD28 is dependent on IL-2. CD4+ T cells from itk−/− mice and itk+/− littermates were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). Anti-CD28 and anti-murine IL-2 were added with anti-murine IL-2R or with recombinant human IL-2 at the beginning of culture. Cell proliferation was measured 72 h after stimulation. a-CD28, anti-CD28 ascites; a-mIL2, anti-murine IL-2 mAb; a-mIL2R, anti-murine IL-2Rα mAb; and hIL-2, recombinant human IL-2.

Mentions: Monoclonal antibodies used for immunofluorescence staining have been described (27). Antibodies used for cell purification include anti-HSA (M1/69), anti-CD8α (53-6.72 and 3.155), anti-I-Ab,d (28-16-8S), anti-I-Ab,d,  j,p,q,u (BP107), anti-rat immunoglobulins, and anti-mouse immunoglobulins (American Type Culture Collection, Rockville, MD). Antibodies used in cell culture include anti-CD3 (500A2 for Figs. 1, 2, 4, and 145-2C11 for Fig. 3), anti-CD28 (37.51), anti-CTLA-4 (9H10), anti-IL-2 (S4B6), anti-IL-2Rα (3C7), and anti-IL-4 (11B11) (PharMingen, San Diego, CA). Antibodies used in the IL-2 ELISA include the capture mAb JES6-1A12 and the detecting mAb JES6-5H4 (PharMingen, San Diego, CA).


Itk negatively regulates induction of T cell proliferation by CD28 costimulation.

Liao XC, Fournier S, Killeen N, Weiss A, Allison JP, Littman DR - J. Exp. Med. (1997)

Cell proliferation induced by  TCR and CD28 is dependent on IL-2.  CD4+ T cells from itk−/− mice and itk+/−  littermates were stimulated with plate-bound  anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). Anti-CD28 and anti-murine IL-2 were added with anti-murine  IL-2R or with recombinant human IL-2 at  the beginning of culture. Cell proliferation  was measured 72 h after stimulation.  a-CD28, anti-CD28 ascites; a-mIL2, anti-murine IL-2 mAb; a-mIL2R, anti-murine  IL-2Rα mAb; and hIL-2, recombinant human IL-2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198978&req=5

Figure 4: Cell proliferation induced by TCR and CD28 is dependent on IL-2. CD4+ T cells from itk−/− mice and itk+/− littermates were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). Anti-CD28 and anti-murine IL-2 were added with anti-murine IL-2R or with recombinant human IL-2 at the beginning of culture. Cell proliferation was measured 72 h after stimulation. a-CD28, anti-CD28 ascites; a-mIL2, anti-murine IL-2 mAb; a-mIL2R, anti-murine IL-2Rα mAb; and hIL-2, recombinant human IL-2.
Mentions: Monoclonal antibodies used for immunofluorescence staining have been described (27). Antibodies used for cell purification include anti-HSA (M1/69), anti-CD8α (53-6.72 and 3.155), anti-I-Ab,d (28-16-8S), anti-I-Ab,d,  j,p,q,u (BP107), anti-rat immunoglobulins, and anti-mouse immunoglobulins (American Type Culture Collection, Rockville, MD). Antibodies used in cell culture include anti-CD3 (500A2 for Figs. 1, 2, 4, and 145-2C11 for Fig. 3), anti-CD28 (37.51), anti-CTLA-4 (9H10), anti-IL-2 (S4B6), anti-IL-2Rα (3C7), and anti-IL-4 (11B11) (PharMingen, San Diego, CA). Antibodies used in the IL-2 ELISA include the capture mAb JES6-1A12 and the detecting mAb JES6-5H4 (PharMingen, San Diego, CA).

Bottom Line: T cells defective in Itk were found to be fully competent to respond to costimulation.The results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways.By negatively regulating the amplitude of signaling upon CD28 costimulation, Itk may provide a means for modulating the outcome of T cell activation during development and during antigen-driven immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA.

ABSTRACT
CD28 is a cell surface molecule that mediates a costimulatory signal crucial for T cell proliferation and lymphokine production. The signal transduction mechanisms of CD28 are not well understood. Itk, a nonreceptor protein tyrosine kinase specifically expressed in T cells and mast cells, has been implicated in the CD28 signaling pathway because of reports that it becomes phosphorylated on tyrosines and associates with CD28 upon cross-linking of the cell surface molecule. To determine whether Itk plays a functional role in CD28 signaling, we compared T cells from Itk-deficient mice and control mice for their responses to CD28 costimulation. T cells defective in Itk were found to be fully competent to respond to costimulation. Whereas the CD3-mediated proliferative response was severely compromised in the absence of Itk, the calcineurin-independent CD28-mediated response was significantly elevated when compared with cells from control animals. The augmented proliferation was not due to increased production of interleukin-2. The results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways. By negatively regulating the amplitude of signaling upon CD28 costimulation, Itk may provide a means for modulating the outcome of T cell activation during development and during antigen-driven immune responses.

Show MeSH
Related in: MedlinePlus