Dermatology Week 1 Practice Exam

Rituximab directly targets B cells. It binds to CD20, a surface protein present on most mature B cells, and flags these cells for destruction. The main ways this happens are antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, with some ability to induce direct cell death as well. Because CD20 is not on stem cells or plasma cells, rituximab depletes circulating and tissue B cells while sparing others, which reduces antibody production and B-cell–mediated antigen presentation. It does not directly modulate T cells, NK cells, or macrophages, though those cells can participate in clearing the opsonized B cells as part of the process.