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Expression and function of CD22, a B-cell restricted molecule
J E Moyron-Quiroz1, S Partida-Sánchez, R Donís-Hernández
1Department of Cellular Biology, Centro de Investigación y Estudios Avanzados del I.P.N., 07360 México D.F., México.
Scandinavian Journal of Immunology
|April 23, 2002
Summary
CD22 is expressed early in B cell development and its expression increases upon stimulation. Unlike B-cell receptor signaling, CD22 is not phosphorylated or associated with CD38 or CD40, suggesting it may not regulate activation by these molecules.
Area of Science:
- Immunology
- Cell Biology
Background:
- CD22 is recognized as an activation marker on mature B lymphocytes.
- Its role in early B cell development and regulation of activation by various stimuli is not fully understood.
Purpose of the Study:
- To investigate the expression pattern of CD22 during B cell ontogeny.
- To examine the functional role of CD22 in B cell activation mediated by the B-cell antigen receptor (BCR), CD38, and CD40.
Main Methods:
- Studied CD22 expression in murine B cells from different lymphoid compartments.
- Analyzed CD22 phosphorylation and association with BCR, CD38, and CD40 upon B cell stimulation.
- Utilized cross-linking techniques for CD38 and CD40 stimulation.
Main Results:
- CD22 is expressed early in B cell development in bone marrow and spleen.
- B cell stimulation via BCR, CD38, and CD40 upregulates CD22 expression within 24 hours.
- CD22 phosphorylation occurs after BCR signaling but not after CD38 or CD40 cross-linking.
- No physical association was found between CD22 and CD38 or CD40.
Conclusions:
- CD22 expression is broader than previously thought, appearing early in B cell ontogeny.
- CD22 phosphorylation and association are specific to BCR signaling.
- CD22 may not play a significant role in downregulating B cell activation induced by CD38 and CD40.