Rituximab depletes CD20-positive B cells, yet patients treated long-term do not develop hypogammaglobulinaemia from the drug alone. The reason is:

• A Rituximab upregulates IL-6, sustaining antibody secretion by surviving B cells
• B Plasma cells lack CD20 expression, so immunoglobulin production continues ✓
• C CD20 is expressed only on malignant B cells, never on normal lymphocytes
• D Immunoglobulins have a half-life of several years, masking depletion indefinitely

Explanation

CD20 appears from the pre-A cell stage through mature A cells but is absent on early pro-A cells and on terminally differentiated plasma cells. Since plasma cells produce circulating immunoglobulin and carry no CD20, rituximab spares them directly, and the stem cell compartment repopulates the A lineage after treatment. Option C is wrong because CD20 is a normal pan-A marker, which is exactly why rituximab also causes A-cell depletion in non-malignant settings.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.