This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Extravascular Changes, Subject name: Pathology
[{'content': 'After binding of complement and antibody on the surface of encapsulated bacteria, the process of phagocytosis by polymorphonuclear leukocytes/macrophages is enhanced by all of the following opsonins, except? \nSelect and explain. \nA. C3b complement protein, B. IgG antibody, C. Mannose binding lectin (MBL), D. CD11b/CD18', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The efficiency of phagocytosis is greatly enhanced when microbes are coated with opsonins for which the phagocytes express high-affinity receptors. The major opsonins are immunoglobulin G (IgG) antibodies, the C3b breakdown product of complement, and ceain plasma lectins, notably mannose-binding lectin and collectins, all of which are recognized by specific receptors on leukocytes. CD11b/CD18 (MAC-1) is macrophage integrin which help in binding of microbes to macrophages, and are not opsonins.', 'role': 'assistant'}]