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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

Itk is not required for the inhibitory signal mediated by  CTLA-4. (A) CD4+ T cells were stimulated with polystyrene beads  coated with various antibodies as indicated. Cell proliferation was measured 72 h after stimulation. (B) CD4+ T cells from itk−/− mice (circles)  and itk+/− littermates (squares) were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence  of anti-CD28 ascites (1:500). CTLA-4Ig was included at the beginning of  culture (closed symbols) together with anti-CD28. Cell proliferation was  measured 72 h after stimulation.
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Figure 2: Itk is not required for the inhibitory signal mediated by CTLA-4. (A) CD4+ T cells were stimulated with polystyrene beads coated with various antibodies as indicated. Cell proliferation was measured 72 h after stimulation. (B) CD4+ T cells from itk−/− mice (circles) and itk+/− littermates (squares) were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). CTLA-4Ig was included at the beginning of culture (closed symbols) together with anti-CD28. Cell proliferation was measured 72 h after stimulation.

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)

Itk is not required for the inhibitory signal mediated by  CTLA-4. (A) CD4+ T cells were stimulated with polystyrene beads  coated with various antibodies as indicated. Cell proliferation was measured 72 h after stimulation. (B) CD4+ T cells from itk−/− mice (circles)  and itk+/− littermates (squares) were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence  of anti-CD28 ascites (1:500). CTLA-4Ig was included at the beginning of  culture (closed symbols) together with anti-CD28. Cell proliferation was  measured 72 h after stimulation.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: Itk is not required for the inhibitory signal mediated by CTLA-4. (A) CD4+ T cells were stimulated with polystyrene beads coated with various antibodies as indicated. Cell proliferation was measured 72 h after stimulation. (B) CD4+ T cells from itk−/− mice (circles) and itk+/− littermates (squares) were stimulated with plate-bound anti-CD3 at different concentrations as indicated, in the presence or absence of anti-CD28 ascites (1:500). CTLA-4Ig was included at the beginning of culture (closed symbols) together with anti-CD28. Cell proliferation was measured 72 h after stimulation.
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