CD20 monoclonal antibodies stimulate extracellular cleavage of the low affinity receptor for IgE (Fc epsilon RII/CD23) in Epstein-Barr-transformed B cells.

This study demonstrates that monoclonal antibodies to the B cell-specific CD20 molecule down-regulate both constitutive and interleukin-4-induced CD23 expression on Epstein-Barr-transformed B cells. This effect of CD20 antibody B1 does not take place at the transcriptional level as shown by the lack of effect on the CD23 mRNA level. Incorporation of 35S-labeled amino acids into CD23 polypeptide chain is not affected either. In cycloheximide-treated cells, B1 increases the decline of CD23 from the cell surface. The disappearance of CD23 molecule correlates with an increase of soluble CD23 fragments detected in the culture medium. Taken collectively, these results indicate that CD20 mAb B1 stimulates the cleavage of the CD23 molecule at the surface of B cells.