Autoimmune haemolytic anaemias. V. studies on the resistance against complement haemolysis of the red cells of patients with chronic cold agglutinin disease.

Experiments are described the results of which sustain the hypothesis that resistance against complement haemolysis, which is a characteristic of the red cells of patients with chronic cold agglutinin disease, is due to the following mechanism: when red cells react with cold auto-agglutinins , they are either haemolysed immediately, or, due to an unknown factor, escape direct haemolysis. In the latter case βE and βA disappear from the cell membrane. To the sites where these proteins have been attached once, no new βE or βA molecules can be bound. Full complement activation thus becomes impossible.