Cold agglutinin disease is an acquired autoimmune hemolytic anemia due to an IgM autoantibody usually directed against the I antigen on red blood cells.

These IgM autoantibodies characteristically will not react with cells at 37 degrees centigrade but only at lower temperatures. Since the blood temperature (even in the most peripheral parts of the body) rarely goes lower than 20 degrees centigrade, only antibodies active at higher temperatures than this will produce clinical effects. In the cooler parts of the body (fingers, nose, ears), agglutination of red blood cells by the IgM antibodies will transiently occur.

Hemolysis results indirectly from attachment of IgM, which in the cooler parts of the circulation binds and fixes complement. When the red blood cell returns to a cooler temperature, the IgM antibody dissociates, leaving complement on the cell. Lysis, or destruction, of cells rarely occurs. Rather, C3b present on the red cells is recognized by Kupffer cells (which have receptors for C3b); and red blood cell formation follows.

Most cases of chronic cold agglutinin disease are of undetermined origin. Others occur in association with Waldenström's macroglobulinemia, a malignant lymphoproliferative disease in which a monoclonal IgM paraprotein is produced.


Also check autoimmune hemolytic anemia which could be ongoing ... underlying this condition:

Autoimmune hemolytic anemia is an autoimmune disorder which causes the premature destruction of red blood cells. There are several related autoimmune blood diseases. A normally red blood cell has a life span of approximately 120 days before the spleen removes it from circulation. Red blood cells are made in the bone marrow and released into circulation. In persons with autoimmune hemolytic anemia, the red blood cells are destroyed prematurely; and bone marrow production of new cells cannot make up for their loss. The severity of this disorder is determined by the length of time the red blood cell survives and by the capability of the bone marrow to continue red blood cell production.

Autoimmune hemolytic anemia is a disorder that occurs in persons who have formerly had a normal red blood cell count. The disorder usually occurs in conjunction with some other medical condition, very often another autoimmune disease. It may sometimes occur alone and without a triggering factor. It affects twice as many women as men, specifically women in the childbearing years. Cold antibody hemolytic anemia most commonly affects elderly persons, and warm antibody hemolytic anemia can affect anyone at any age