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A role in B cell activation for CD22 and the protein tyrosine phosphatase SHP

G M Doody1, L B Justement, C C Delibrias

  • 1Wellcome Trust Immunology Unit, Department of Medicine, University of Cambridge, School of Clinical Medicine, UK.

Science (New York, N.Y.)
|July 14, 1995
PubMed

Insights

CD22 protein on B cells acts as a molecular switch. It regulates B cell activation by interacting with SHP, a phosphatase, influencing immune responses.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • CD22 is a protein associated with membrane immunoglobulin (mIg) on B cells.
  • Upon mIg ligation, CD22 undergoes tyrosine phosphorylation.

Purpose of the Study:

  • To investigate the role of CD22 in regulating B cell signaling.
  • To understand how CD22 influences the activation threshold of B cells.

Main Methods:

  • Studying CD22 phosphorylation and its interaction with SHP (a protein tyrosine phosphatase).
  • Analyzing the effect of CD22 ligation on mIg-mediated B cell activation.
  • Investigating CD22 localization in secondary lymphoid organs.

Main Results:

  • Tyrosine-phosphorylated CD22 binds and activates SHP, which negatively regulates mIg signaling.
  • Preventing CD22 coaggregation with mIg reduces the B cell activation threshold by 100-fold.
  • CD22 may be sequestered from mIg by T cell counterreceptors in lymphoid organs.

Conclusions:

  • CD22 functions as a molecular switch for SHP, modulating B cell signaling.
  • CD22 may direct mIg signaling to T cell-rich areas in secondary lymphoid organs.

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