A child with recurrent severe candidiasis of the mouth, nails and skin since infancy also has endocrinopathy. Mutations in the autoimmune regulator (AIRE) gene are identified. The underlying immunological defect predisposing to this chronic mucocutaneous candidiasis lies primarily in which arm of immunity?

• A IgE mediated mast cell degranulation
• B Complement C3 deposition
• C Classical MHC class II antigen presentation
• D Th17 cell and IL-17 axis responses ✓

Explanation

Protection against mucosal and cutaneous Candida depends on Th17 cells producing IL-17, which recruits neutrophils and induces epithelial antimicrobial peptides. Defects in the IL-17 pathway, including STAT3 loss of function causing hyper IgE syndrome and AIRE mutations causing autoimmune polyendocrinopathy candidiasis ectodermal dystrophy, produce chronic mucocutaneous candidiasis. Complement defects predispose to pyogenic and Neisseria infections, and IgE defects to staphylococcal abscesses rather than persistent candidiasis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.