Donath landsteiner antibody is seen in?

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