1. Leukocytes from thirteen cases of leukemia were isolated, homogenized, and extracted in 0.88 M sucrose, 0.14 M NaCl, and 2.0 M NaCl solutions. All thirteen 0.88 M sucrose, twelve of thirteen 2.0 M NaCl, and seven of the thirteen 0.14 M NaCl extracts, were found to contain a hemolysin and agglutinin active against normal and trypsinized erythrocytes.
2. The hemolysin and agglutinin of leukemic leukocyte extracts was found to differ from coating antibody eluted from erythrocytes of patients with acquired hemolytic anemia, from β-glucuronidase, and from anti-H agglutinin. In spite of great similarities, the hemolysin and agglutinin differed in certain respects from the lysin-inhibitor complexes that have been extracted from tissues.
3. An inhibitor of the hemolysin and agglutinin of leukemic leukocyte extracts was found in normal serum. This inhibitor is stable at 56° C. for 30 minutes, is not dialyzable, is not exhausted from leukemic sera, and apparently does not permanently change the hemolysin or agglutinin.
4. The possible role of the leukemic leukocyte hemolysin and agglutinin in instituting premature senescene of the erythrocyte resulting in a "hemopathic" type of hemolytic anemia is discussed.