This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2019, Subject name: Pathology
[{'content': 'MHC II is associated with:- \nSelect and explain. \nA. Antigen presenting cells, B. Red blood cells, C. Platelets, D. Epithelial cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: During antigen recognition, CD4 molecules bind to class II MHC molecules that are displaying antigen (Fig. 6-5), and CD8 molecules bind to class I MHC molecules, and the CD4 or CD8 coreceptor initiates signals that are necessary for activation of the T cells. Because of this requirement for coreceptors, CD4+ helper T cells can recognize and respond to antigen displayed only by class II MHC molecules, whereas CD8+ cytotoxic T cells recognize cell-bound antigens only in association with class I MHC molecules; this segregation is described later. Integrins are adhesion molecules that promote the attachment of T-cells to APCs. To respond, T cells have to recognize not only antigen- MHC complexes but additional signals (CD 28) provided by antigen- presenting cells.', 'role': 'assistant'}]