"False positive" acidified serum test in a preleukemic dyserythropoiesis.

In a case of preleukemic dyserythropoiesis, in vitro red cell lysis tests showed a positive acidified serum test whose characteristics are described. The positive acidified serum test occurred in 10 normal sera, in 1 serum with complete deficiency of the fourth component of complement and in 1 serum with complete deficiency of the second component of complement. The test was found negative with 2 hyperlipemic sera. The other in vitro red-cell lysis tests were negative. The results of the in vitro lysis tests were different from the results obtained in paroxysmal nocturnal hemoglobinuria and congenital dyserythropoietic anemias.