Features of cold agglutinin disease:
(1) IgM autoantibodies bind to I antigen on erythrocytes
(2) binding occurs optimally below body temperature
(3) because of the nature of IgM antibodies the binding causes agglutination AND activation of the classic complement system via C1s, resulting in a hemolytic anemia
(4) there is an increased risk of thromboembolism
Conditions with cold agglutinins:
(1) cold agglutinin syndrome: transient, secondary to infection, an autoimmune disease or in association with a malignancy
(2) cold agglutinin disease: clonal, low-grade B-cell lymphoproliferative disorder
A patient with hemolysis associated with cold agglutinins:
(1) develops an anemia, that may range from mild to severe
(2) develops fatigue and a reduced quality of life
(3) may become transfusion dependent
