Donath-Landsteiner autoimmune hemolytic anemia in children. A study of 22 cases.

During the last 4 years, we have studied a total of 531 adults and 68 children with clinically and serologically well-defined forms of immune hemolytic anemias. Among these, Donath-Landsteiner (DL) hemolysis was the underlying disease in 22 of the 68 children (32.4%), but was not observed in adults. All children with DL hemolysis suffered from acute infections presumably of viral origin. In none of the cases was the DL hemolysis suspected clinically. Boys were more often affected than girls. The hemolytic episodes were severe, but resolved within few weeks. Serologically, all patients had a strongly positive direct antiglobulin test (DAT) using anti-C3d reagents, but a weak (n = 6) or negative (n = 16) IgG-DAT. DL hemolysins were always weak and transient, detectable with enzyme-treated red blood cells (RBC) in all, with untreated RBC in 12 of 22 sera. To explore the reason why these weak antibodies can cause extensive hemolysis in vivo, we compared the action of DL antibodies and of cold agglutinins (anti-I) on RBC by several reincubations at 4 and at 37 degrees C. The data obtained from this experiment demonstrate a stronger aggravation of hemolysis by DL than by anti-I antibodies, presumably due to low-affinity interaction between the cells and DL antibodies.