The Integrin Associated Protein CD47 Modulates Murine B cell Maturation

• CD47 is a ubiquitously expressed transmembrane glycoprotein that can function as a ligand for the inhibitory ITIM-receptor signal-regulatory protein α (SIRPα), which is highly expressed by myeloid cells but not lymphoid cells. In secondary lymphoid organs, the interaction between CD47 and SIRPα has been shown to be important in the homeostasis of T lymphocytes and CD8- dendritic cells, but a possible role in regulating B cell homeostasis remain unidentified. In the present study, we show that CD47-/- mice displayed reduced numbers of mature B cells in the bone marrow and in blood, and a reduced fraction of follicular B cells in the spleen. On the contrary, the fraction of marginal zone B cells was increased but normally localized to the splenic MZ. This B cell phenotype was found to be associated with an increasing age. However, we were unable to detect increased levels of autoantibodies in CD47-/- mice. From this investigation, no conclusion can be made whether these effects are B cell-intrinsic or secondary to other cell abnormalities. In conclusion, CD47-/- mice manifested a fairly similar B cell phenotype as we have previously described in SIRPα mutant mice (lacking the SIRPα cytoplasmic domain) and suggest that SIRPα and its ligand CD47 are important for steady-state homeostasis of B cells. 

Nyckelord

CD47

Bone marrow

Marginal zone B cells

Follicular B cells

immunologi

Immunology

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