CD20: an ideal target antigen
CD20 is a transmembrane surface antigen that appears to be involved in the regulation of B-cell growth and differentiation, possibly by functioning as a calcium channel (Janas et al 2005; Li et al 2003). The CD20 antigen has a number of properties that make it an attractive target for monoclonal antibody therapy in NHL.
CD20 is reliably expressed on most NHL malignant B-cells as well as normal Bcells, but not on stem cells, mature plasma cells or other tissues (Anderson et al 1984; Nadler et al 1981), therefore it allows eradication of targeted cells without causing excessive toxicity because B-cells will continue to differentiate from stem cells, thus restoring normal B-cell numbers and serum immunoglobulin levels will be maintained by unaffected plasma cells.
Furthermore, CD20 expression is stable and it is not internalised after antibody binding (Press et al 1987), allowing initiation of immune processes and induction of apoptosis. CD20 provides an enduring target; it is not normally shed from the cell surface, and serum levels of the CD20 antigen are undetectable in most patients (Einfeld et al 1988).
References
- Janas E, et al. Biochem Soc Symp 2005; 165-175.
- Li H, et al. J Biol Chem 2003; 278: 42427-42434.
- Anderson KC, et al. Blood 1984; 63: 1424-1433.
- Nadler LM, et al. J Clin Invest 1981; 67: 134-140.
- Einfeld DA, et al. EMBO J 1988; 7: 711-717.
- Press OW, et al. Blood 1987; 69: 584-591.
