Paroxysmal cold hemoglobinuria

Paroxysmal cold hemoglobinuria (PCH) or Donath–Landsteiner hemolytic anemia (DLHA) is an autoimmune hemolytic anemia featured by complement-mediated intravascular hemolysis after cold exposure. It can present as an acute non-recurrent postinfectious event in children, or chronic relapsing episodes in adults with hematological malignancies or tertiary syphilis. Described by Julius Donath (1870–1950) and Karl Landsteiner (1868–1943) in 1904, PCH is one of the first clinical entities recognized as an autoimmune disorder.

is a result of cold-reacting antibody immunoglobulin (Ig) induced hemolytic response inside vessels leading to anemia and, thus, a cold antibody autoimmune hemolytic anemias (CAAHA).

In most patients with DLHA, the antibody selectively targets against the red blood cells on-surface antigen called the antigen P or antigen I, respectively. Most cases were found to be owing to polyclonal IgG. Nonetheless, IgM-induced DLHA has already also been described in the past. For example, there was a case study reporting that autoimmune hemolytic anemia where an IgA Donath–Landsteiner denoted as [D-L] antibody appeared to cause Donath–Landsteiner cold hemoglobinuria. The most notable difference between DLHA and CAD (cold agglutinin disease) is the causative agent. For cold agglutinin disease, the causative agent is constantly owing to a cold-active IgM antibody.