A patient with a genetic defect has impaired Class II MHC protein expression on antigen-presenting cells (APCs). If exposed to a novel pathogen, which consequence is most likely?

💡 Explanation

Class II MHC molecules are essential for presenting antigens to helper T cells, thereby initiating adaptive immune responses. Because impaired MHC II expression reduces helper T cell activation, rather than enhancing CTL responses or complement, therefore the adaptive immune response will be blunted.

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