Figure 1

Donath-Landsteiner antibody test. Hemolysis of donor erythrocytes was observed when patient serum (tube 7) or a mixture of patient serum and normal serum (to provide complement; tube 9) was incubated at 0°C for 30 minutes, followed by 37°C for 60 minutes. Little or no hemolysis was seen when patient serum or mixed serum was incubated at 0°C for 90 minutes (tubes 1 and 3) or 37°C for 90 minutes (tubes 4 and 6). No hemolysis was observed in control tubes containing normal serum only (tubes 2, 5, 8).