A 25-year-old man has recurrent sinopulmonary infections, low serum IgG/IgA/IgM, absent B cells in peripheral blood but normal T-cell counts. He is found to have a mutation in Bruton's tyrosine kinase (BTK). Which serology pattern is expected for his vaccination history?

• A Positive isohemagglutinins (anti-A and anti-B) and positive tetanus antibody titres
• B Absent isohemagglutinins and undetectable vaccine antibody titres ✓
• C Normal vaccine antibody titres because T-cell function is intact
• D Positive IgM responses only, as IgM production is T-cell independent

Explanation

X-linked agammaglobulinaemia (Bruton's disease) results from BTK mutation causing arrest of B-cell development at the pre-B stage; no mature B cells or plasma cells are formed. Consequently, all immunoglobulins are absent or severely reduced. Isohemagglutinins (naturally occurring antibodies to blood group antigens) require B-cell function and will be absent. Vaccine responses to both T-dependent and T-independent antigens will be absent. T-cell function is unaffected, but antibody production depends on B cells.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.