cold agglutinin disease

cold agglutinin disease

Etymology: AS, kald + L, agglutinare, to glue, dis, without; Fr, aise, ease

a disorder characterized by autoantibodies that agglutinate red blood cells at below normal body temperatures. They occur in the sera of patients with mycoplasmal pneumonia.

cold agglutinin disease

Cold agglutinin syndrome Clinical immunology An immune disorder characterized by IgM autoantibodies that optimally agglutinate RBCs at very low temperatures–eg, 4ºC; low titers–< 1:32 of cold agglutinins–CAs are detectable in many normal subjects; polyclonal CAs ↑ after certain infections–eg, mycoplasma, CMV, EBV, trypanosomiasis, and malaria, peak in 2-3 wks and are insignificant if non-hemolytic; CAs may occur in any Pt with acquired hemolytic anemia and a positive direct Coomb's test; certain antibodies have been implicated–eg, anti-I, -i, -Pr, -Gd, Sd^a. See Autoantibody. Cf 'Room temps. '.

cold agglutinin disease

Any of a group of disorders marked by hemolytic anemia, obstruction of the microcirculation, or both. It is caused by agglutination of red blood cells by immunoglobulins that precipitate at cool or cold temperatures. The most common symptom is Raynaud's phenomenon. Cold agglutinin disease often occurs transiently after infection with Mycoplasma pneumoniae or Epstein-Barr virus. Often the cause is idiopathic.

agglutinin

any substance causing agglutination (clumping together) of cells, particularly a specific antibody formed in the blood in response to an invading agent. Such agglutinating antibodies (see immunoglobulin) function as part of the immune mechanism of the body. When the invading agents that bring about the production of agglutinins are bacteria, the agglutinins produced bring about agglutination of the bacterial cells both in vivo and in vitro.

Erythrocytes also may be agglutinated by agglutinins that are naturally present in the blood, such as the presence of anti A antibody in humans with the blood group B erythrocytes, or such agglutinins may also be formed in response to the entrance of noncompatible blood cells into the bloodstream. A transfusion reaction is an example of the result of agglutination of blood cells brought about by agglutinins present in the recipient's blood.

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cold agglutinin

antibody that acts only at low temperature.

cold agglutinin disease

an autoimmune disease in which erythrocyte autoantibodies, usually IgM, are most active at temperatures below 98.6°F (37°C). Agglutination occurs in capillaries of the extremities (tail, ears, nose and feet), particularly on exposure to cold, resulting in tissue necrosis in those areas. Hemolytic anemia is a variable feature.

group agglutinin

antibody made against a particular organism. One that has a specific action on certain organisms, but will agglutinate other, usually related species as well.

H agglutinin

one that is specific for flagellar antigens of bacteria.

immune agglutinin

a specific antibody found in the blood after recovery from the disease or injection of the microorganism.

incomplete agglutinin

antibody that at appropriate concentrations fails to agglutinate the homologous antigen for steric reasons.

normal agglutinin

a specific antibody found in the blood of an animal or of humans that has had no known exposure to the antigen with which it combines; these may be natural antibodies such as those directed against A and B blood group antigens in humans or cross-reacting antibodies produced after infection with a related microorganism.

O agglutinin

antibody specific for somatic or cell wall antigens of a bacterium.

partial agglutinin

antibody which agglutinates organisms closely related to the specific antigen, but at a lower dilution.

warm agglutinin

an incomplete antibody that sensitizes and reacts optimally with erythrocytes at 98.6°F (37°C).