Pathophysiology Exam 1: Immunodeficiency and Autoimmune Disease Practice Exam

Defects in the IL-17 signaling axis disrupt a key mucosal defense against Candida. IL-17 produced by Th17 cells signals epithelial cells to make antimicrobial peptides and to recruit neutrophils to surfaces like mouth, gut, and skin. When this pathway is impaired—due to mutations in IL-17 ligands, the IL-17 receptor, or downstream signaling components—the mucosal barrier can’t effectively clear Candida, leading to chronic mucocutaneous candidiasis.

Other listed immunodeficiencies involve B-cell defects or broad T-cell failures that cause a wider spectrum of infections, but they don’t specifically hit the IL-17–dependent mucosal defense that underlies chronic mucocutaneous candidiasis. So the immunodeficiency most associated with CMC via IL-17 pathway defects is a primary immunodeficiency affecting IL-17 signaling.