This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Perforins are produced by: \nSelect and explain. \nA. Cytotoxic T cells, B. Suppressor T cells, C. Memory helper T cells, D. Plasma cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Perforins are hole forming proteins synthesized by cytotoxic T-cells. They can perforate the plasma membrane of the target cells that are under attack by CD8+ lymphocytes. Granzymes are delivered into the target cells through these holes formed by perforins. In addition, the perforin pores allow water to enter the cells, thus causing osmotic lysis.', 'role': 'assistant'}]