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': "Donath landsteiner antibody is seen in? \nSelect and explain. \nA. PNH, B. Waldenstrom's macroglobulinemia, C. Paroxysmal cold hemoglobinuria, D. Malaria", 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Paroxysmal cold hemoglobinuria Paroxysmal cold hemoglobinuria (PCH) o PCH is characterized by intermittent massive intravascular hemolysis frequently with hemoglobinuria at low temprature. o The autoantibodies are of IgG class, also known as Donath-Landsteiner antibody. o These antibodies are directed against P-antigen on RBC. o Antigen antibody complex on the red blood cell activates complement. o As a result, large amount of membrane attack complex forms which destroys red cells directly --> intravascular hemolysis. o Causes are : - Syphilis, Mycoplasma, Mumps, Measles, Flu syndrome", 'role': 'assistant'}]