Rituximab is directed against which antigen?

Rituximab is directed against which antigen?

• A. CD45
• B. CD20
• C. CD33
• D. CD54

Answer: (B)

Rituximab binds to CD20, a protein on the surface of mature B cells. By attaching to CD20, it flags these B cells for destruction through immune mechanisms such as complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity, and it can directly trigger B-cell death. Because CD20 is present on most mature B cells but not on hematopoietic stem cells or plasma cells, this approach can deplete B cells while allowing normal immune recovery later. Other antigens listed are not targets of rituximab: CD45 is a common leukocyte marker found on many white cells, CD33 is a myeloid marker, and CD54 (ICAM-1) is an adhesion molecule. Rituximab’s action is specifically tied to CD20 on B cells.

Rituximab binds to CD20, a protein on the surface of mature B cells. By attaching to CD20, it flags these B cells for destruction through immune mechanisms such as complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity, and it can directly trigger B-cell death. Because CD20 is present on most mature B cells but not on hematopoietic stem cells or plasma cells, this approach can deplete B cells while allowing normal immune recovery later.

Other antigens listed are not targets of rituximab: CD45 is a common leukocyte marker found on many white cells, CD33 is a myeloid marker, and CD54 (ICAM-1) is an adhesion molecule. Rituximab’s action is specifically tied to CD20 on B cells.