A patient with a genetic defect has impaired cytotoxic T lymphocyte (CTL) function. Why does this deficiency increase the risk of virally induced tumors?

💡 Explanation

CTLs recognize and kill virally infected cells that present viral antigens on MHC class I molecules. Reduced CTL function impairs the immune system's ability to eliminate these infected cells, because the virus can replicate and cause tumors; therefore, decreased killing of infected cells is the correct answer rather than antibody neutralization, complement, or phagocytosis, which have different roles.

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