Donath-Landsteiner Hemolytic Anemia
a.k.a. Paroxysmal Cold Haemoglobinuria
Paroxysmal Cold Haemoglobinuria (PCH) is an autoimmune hemolytic anemia, caused by cold-reacting immunoglobulins. It primarily affects children and tends to cause a quite severe, but transient, disease. The usual trigger for the formation of the cold-reacting Polyclonal Immunogloblulin G (IgG) autoantibodies is an episode of infection. The episode usually, but not always, follows a period of exposure to cold. It is usually a transient postinfectious or postvaccination problem that resolves, but it may cause significant morbidity. The degree of haemolysis is variable but may lead to an acute onset of intravascular haemolysis and haemoglobiuria.
Cross-reactivity (between antibodies formed against microbial antigens and the red-cell membrane P-antigen) inducees intravascular haemolysis through complement activation. The antibodies detectable in the blood of those who suffer from PCH are known as Donath-Landsteiner antibodies.
It is a very rare illness; there are no reliable population-incidence figures, but it is believed to be respnosible for about 40% of all autoimmune haemolytic anaemias that affect children (lower percentage for adults). Although the vast majority of cases occur in children, adults may rarely be affected. The acute, transient form of PCH, by far the most usual modern presentation, is much more common in children.
Viral infections – measles, mumps, adenovirus, chickenpox, influenza A, cytomegalovirus, Epstein-Barr virus.
Bacterial infections – Haemophilus influenzae, Mycoplasma pneumoniae and Treponema pallidum (a chroni recurrent form is associated with secondary, tertiary or congentila syphilis).
Postvaccination syndrome – particularly measles vaccine.
Rarely, when it affecs adults, it may be precipitated by an underlying neoplasm.
Very rare chronic idiopatic/primary autoimmune disease form (usually seen in adults).
Links to websites for further research