A 35-year-old woman with common variable immunodeficiency (CVID) is found to have absent B cells and very low all immunoglobulin classes. She has recurrent sino-pulmonary infections and Giardia lamblia diarrhoea. What is the expected T-cell status?

• A Absent T cells with normal NK cells
• B Markedly reduced CD4+ T cells similar to HIV infection
• C Absent T and B cells with normal monocytes (SCID)
• D Normal T-cell numbers with impaired B-cell maturation ✓

Explanation

CVID is characterised by failure of B-cell terminal differentiation into plasma cells despite generally normal or near-normal T-cell numbers and counts; the defect lies in B-cell maturation and class-switch recombination. This distinguishes CVID from X-linked agammaglobulinemia (no B cells, T cells normal) and SCID (both T and B cell absence). Giardia is a classic infection in hypogammaglobulinaemia because secretory IgA at mucosal surfaces is absent. T-cell function may be partially impaired in CVID but T-cell lymphopenia is not the primary defect.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.