MEDizzy - A 13-year-old girl has a gastrointestinal viral infection.

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Immune System Diseases

A 13-year-old girl has a gastrointestinal viral infection. Within the cytoplasm, viral proteins are processed to peptides. These peptides are displayed with MHC I molecules on the surface of macrophages. A receptor heterodimer made up of an α and a β polypeptide chain recognizes the peptide. Which of the following cells has this receptor?

ExplanationThe adaptive immune system requires the presentation of antigens to effector cells. Intracellular pathogens such as viruses are displayed by MHC I molecules to both CD4 and CD8 T cells with αβ T cell receptors. Some CD8 cells secrete cytokines, but most are cytotoxic. B lymphocytes express immunoglobulin receptors that primarily react to extracellular antigens, such as those derived from bacteria, as an adaptive humoral immune response. Dendritic cells are a type of antigen-presenting cell. Natural killer cells are part of innate immunity and react against cells when they do not display MHC molecules. A subset of T cells beneath epithelia displays γδ receptors that are part of an innate immune response.