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Fyn tyrosine kinase associated with Fc epsilon RII/CD23: possible multiple roles in lymphocyte activation

K Sugie1, T Kawakami, Y Maeda

  • 1Department of Biological Responses, Kyoto University Medical School, Japan.

Proceedings of the National Academy of Sciences of the United States of America
|October 15, 1991
PubMed

Insights

The low-affinity IgE receptor (Fc epsilon RII/CD23) activates lymphoid cells. This receptor signals through protein-tyrosine kinase p59fyn, suggesting its role in immune cell activation.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Signaling

Background:

  • The low-affinity IgE receptor (Fc epsilon RII), also known as CD23, is expressed on activated lymphoid cells.
  • The precise mechanism of Fc epsilon RII/CD23-mediated signal transduction remains incompletely understood.

Purpose of the Study:

  • To investigate the signal transduction pathway of Fc epsilon RII/CD23.
  • To identify the role of protein-tyrosine kinases in Fc epsilon RII/CD23 activation.

Main Methods:

  • Transfection of Fc epsilon RII cDNA into YT human natural killer-like cells (YTSER cells).
  • Cross-linking of Fc epsilon RII/CD23 using an anti-Fc epsilon RII monoclonal antibody (H107).
  • Detection of interleukin 2 receptor/p55 (Tac) induction as a marker of cell activation.
  • Co-immunoprecipitation to assess the association of Fc epsilon RII/CD23 with protein-tyrosine kinases.

Main Results:

  • Cross-linking Fc epsilon RII/CD23 markedly enhanced interleukin 2 receptor/p55 expression in YTSER cells.
  • Similar Fc epsilon RII/CD23-mediated activation was observed in an Epstein-Barr virus-transformed B-cell line and primary leukemic B cells.
  • Fc epsilon RII/CD23 was found to be physically associated with the src family tyrosine kinase p59fyn, but not p56lck.

Conclusions:

  • Fc epsilon RII/CD23 provides activation signals to both engineered and naturally occurring B cells.
  • The protein-tyrosine kinase p59fyn is implicated in Fc epsilon RII/CD23-mediated signal transduction.
  • p59fyn may have multiple functions in Fc epsilon RII/CD23-mediated activation of YT cells.

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