Cold agglutinins commonly cause clumping (agglutination) of red blood cells. Cold agglutinins are IgM antibodies that can develop as a result of viral or Mycoplasma infections, as well as in the context of plasma cell or lymphoid neoplasms. Red cell agglutination can interfere with red blood cell indices. These may be corrected by heating the sample at 56°C for 30 minutes or adding ethylenediaminetetraacetic acid (EDTA) to prevent further agglutination. Autoantibodies can also cause red blood cell agglutination. These autoantibodies are usually associated with autoimmune diseases such as lupus erythematosus, but they can also occur in the setting of chronic infection or after exposure to chemicals. Autoimmune hemolytic anemia is caused by autoantibodies that attack and destroy red blood cells. This can lead to decreased oxygen delivery to body tissues and can be life-threatening if not treated promptly. Chemicals can also cause red blood cell agglutination. If you work in an environment where you are exposed to compounds such as mercury, lead, or arsenic, you may develop chemical agglutinations. The symptoms of lead poisoning include nervous system problems, impaired hearing, memory loss, changes in mood, confusion, weakness, paralysis, and death.