Ionic‐strength‐dependent autohaemolysins recognizing papain‐sensitive antigens

Autoimmune hemolytic anemia caused by warm-reacting IgM-class antibodies

“…26 In Patient 1, the condition was secondary to non-Hodgkin's lymphoma, whereas Patient 2's condition was idiopathic. A number of the previous cases also were secondary to a variety of diseases, including non-Hodgkin's lymphoma, 20,25,27,28 Hodgkin's disease, 11 chronic myeloid leukemia, 11 primary biliary cirrhosis, 11 systemic lupus erythematosus, 11,17 polyarthritis, 24 rheumatoid arthritis, 19 collagen vascular disease, 20 infection, 20,26 and methyl dopa therapy; 16 whereas in others, the condition was idiopathic. 11,15,20,21,25 The autoantibodies in our cases were predominantly cell bound and showed no obvious specificity within the routinely identified blood group systems; however, it should be noted that they were not tested for sialidasesensitive determinants (anti-En a , Pr, Wr b , or Ge), which have been particularly associated with warm-reacting IgM-class autoantibodies and severe, sometimes fatal, hemolysis.…”

“…11,15,20,21,25 The autoantibodies in our cases were predominantly cell bound and showed no obvious specificity within the routinely identified blood group systems; however, it should be noted that they were not tested for sialidasesensitive determinants (anti-En a , Pr, Wr b , or Ge), which have been particularly associated with warm-reacting IgM-class autoantibodies and severe, sometimes fatal, hemolysis. 10,18,23,25,27 Other reported specificities have included anti-c, 22 anti-e, 19 anti-H, 28 anti-I, 11 and anti-I T . 15 Warm IgM autoantibodies almost always bind complement, as in Patients 1 and 2, and can be conveniently classified by their in vitro serologic reactions into agglutinins and hemolysins, which may be either incomplete or complete.…”

“…21 Fortunately, these antibodies are rare, with only 4 out of 340 examples of warm hemolysins reacting with untreated RBCs. 9 Hemoglobin levels are typically low (e.g., < 50 g/L), 21 and patient treatment, based on blood transfusion and high-dose steroids, can be difficult, 30 although sometimes a good response has been reported; 27 plasma exchange and complement inhibitory agents have been suggested on theoretical grounds. 30 Occasional cases may have a more benign prognosis and two patients in which the in vitro hemolytic activity was ionic-strength dependent had no evidence of hemolysis in vivo.…”

“…30 Occasional cases may have a more benign prognosis and two patients in which the in vitro hemolytic activity was ionic-strength dependent had no evidence of hemolysis in vivo. 27 Some patients do not fit into these groups and a series of children were described with warm IgM RBC autoantibodies that were nonagglutinating and noncomplement binding. 26 Hemolysis was generally severe (hemoglobin levels ranging from 30-94 g/L), but tended to respond well to steroids and blood transfusions.…”