B220 on B cells = CD45R

[Apoptosis]

B220 is a surface marker on B cells.

 

B220 is rather another name for CD45R, the ligand which is present on helper T cells that binds to CD22 on APC to activate T helper cells by cleaving phosphates off certain signalling molecules of the CD3 apparatus.

 

This being so, does it not mean that B cells binds to APC? This confused me, as I knew of B cell – T helper cells interaction, but not the former.

B cell itself is an APC, so it further does not make sense.

 

Help?

[dttom]

Even if B cells contain CD45R and CD45R is found to have interaction with CD22 does not imply B cells would interact with all cells expressing surface CD22. Interaction might requires other intermolecular adhesion. And CD22 is present in B cells, so it actually suggests the APC role of B lineage.

[Bjorn]

Hi Apoptosis,

 

B220 is rather another name for CD45R

B220 isn't exactly another name for CD45R, but rather an isoform of CD45R predominantly found on B cells (hence the B) weighing 220 Kd.

 

CD45R is found to have interaction with CD22

As far as I'm aware CD22 (Siglec 2) binds to sialic acids on glycans of glycoproteins and glycolipids. I'm not aware of CD22 binding to B220.

 

As dttom said, even if these molecules do interact this doesn't necessarily mean that B-cells and APC interact through cell to cell contact. Usually, cell to cell interaction involves many receptors and ligands interacting.

 

Hope that helps!