Cold agglutinins are IgM autoantibodies that cause red blood cells to agglutinate and undergo lysis at temperatures below 37°C. Cold agglutinin disease is a rare autoimmune disease characterized by high levels of these cold-sensitive antibodies directed against red blood cells. Intraoperatively during procedures involving hypothermia and cardiopulmonary bypass, cold agglutinins can be detected by mixing blood with cold cardioplegia solution or diluting the blood sample to simulate bypass conditions to check for red blood cell agglutination. Cold agglutinins can be monoclonal or polyclonal in nature, with monoclonal agglutinins seen in lymphoproliferative disorders and polyclonal forms associated

1. COLD AGGLUTINS
Manu Jacob

2. Agglutination in the venous reservoir and oxygenator during
hypothermia and cardiopulmonary bypass. The agglutination can be
seen as a white aggregate forming in the reservoir (circle and arrows)

3. • Cold agglutinins are IgM autoantibodies that react with erythrocytes at
temperatures below 37° .
• Cold agglutinin disease is a rare autoimmune disease characterized by the
presence of high concentrations of circulating cold sensitive antibodies,
usually IgM and autoantibodies that are also active at temperatures below 30 °C
(86 °F) directed against red blood cells, causing them to agglutinate and
undergo lysis.
• It is a form of autoimmune hemolytic anemia, specifically one in which antibodies
bind red blood cells only at low body temperatures, typically 28–31 °C.

4. • Intraoperatively, low-thermal-amplitude CAs can be determined by mixing
cold cardioplegia with some of the patient's blood to check for separation of
cells.
• If there is concern about CAs after routine testing, the sample can also be
diluted to simulate CPB, cooled, and inspected for RBC agglutination.

6. COLD AGGLUTTINS
POLYCLONAL MONOCLONAL
PARA INFECTIOUS NATURALLY OCCURING
CHRONIC LYMPHO PROLIFERATIVE

7. • Monoclonal CAs, generally belonging to the IgM isotype, are observed in patients
with lymphoproliferative disorders or suffering from the ‘idiopathic’ chronic cold
agglutinin disease.
• Polyclonal CAs, also belonging to the IgM isotype, may be found in patients with various
infectious diseases, but more particularly in patients with Epstein–Barr virus or Mycoplasma
pneumoniae infection.
The evaluation of the clonality of CAs, that are frequently at very low concentrations in serum, can
be easily performed using 2D-PAGE.
CAs are isolated from serum by cold absorption of immunoglobulins on red bloods cells. After
several cold washes, red blood cells coated with CAs are rewarmed to 37°C. After centrifugation,
the supernatant is collected and studied with 2D-PAGE.
As mentioned in the previous section, polyclonal IgM are quite easily differentiated from
monoclonal IgM according to their different electrophoretic patterns

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