A 15-year-old girl develops malaise, headache, and low-grade fever, followed by pharyngitis and cervical lymph node enlargement as a result of infectious mononucleosis caused by Epstein-Barr virus (EBV). Her acute symptoms resolve within 2 weeks, and the fatigue improves within 3 months. All of the following are required for CD8⁺ cytotoxic T lymphocyte (CTL) recognition and killing of EBV-infected cells EXCEPT:
A)β₂-Microglobulin
B)HLA-A, -B or -C
C)CD28
D)LFA-1 (leukocyte function-associated antigen-1)
E)TAP (transporter associated with antigen processing)

Question

Quizplus · Accepted Answer

CD28 is not involved in antigen recognition by T cells, but rather, in costimulation. Cell-mediated immunity against intracellular organisms, such as viruses, is largely mediated by class I-restricted T cells, such as cytotoxic T lymphocytes (CTLs). The class I MHC molecules are HLA-A, HLA-B, and HLA-C. CTLs recognize complexes of viral peptides with class I MHC molecules. β₂-Microglobulin is the nonpolymorphic, noncovalently associated polypeptide chain of MHC class I molecules. TAP is a critical protein involved in the processing and presentation of antigen by class I MHC. LFA-1 is an important integrin mediating adhesion of the CD8⁺ T cells to virus-infected target cells.

A 15-Year-Old Girl Develops Malaise, Headache, and Low-Grade Fever, Followed