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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.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 results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways.

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.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 results suggest that Itk has distinct roles in the CD3 versus the CD28 signaling pathways.

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