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Identification of CD22 Ligands on Bone Marrow Sinusoidal Endothelium Implicated in CD22-dependent Homing of Recirculating B Cells

CD22 is a B cell–specific transmembrane protein known to function as a negative regulator of B cell signaling. It has also been implicated in cell adhesion through recognition of α2,6-linked sialic acids on glycans of target cells. Previous studies showed that CD22-deficient mice had a strongly redu...

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Detalles Bibliográficos
Autores principales: Nitschke, Lars, Floyd, Helen, Ferguson, David J.P., Crocker, Paul R.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1999
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2193059/
https://www.ncbi.nlm.nih.gov/pubmed/10224292
Descripción
Sumario:CD22 is a B cell–specific transmembrane protein known to function as a negative regulator of B cell signaling. It has also been implicated in cell adhesion through recognition of α2,6-linked sialic acids on glycans of target cells. Previous studies showed that CD22-deficient mice had a strongly reduced population of mature recirculating B cells in the bone marrow despite normal B cell development. Using a soluble recombinant form of the receptor (CD22-Fc), we demonstrate here that sialylated ligands for CD22 are expressed on sinusoidal endothelial cells of murine bone marrow but not on endothelial cells in other tissues examined. Injection of CD22-Fc revealed that the CD22 ligands in the bone marrow were accessible to the circulation. Treatment of mice with either CD22-Fc or affinity-purified anti-CD22 antibody led to an ∼50% reduction in mature recirculating B cells in the bone marrow without affecting numbers in the spleen. Finally, consistent with the notion that CD22 is a homing receptor, we show that compared with wild-type mice, CD22-deficient animals have a lower number of immunoglobulin M–secreting plasma cells in the bone marrow.