Fumarase Activity of Human Leukocytes and Erythrocytes

1. The results of over 400 assays of fumarase activity in separated leukocytesand erythrocytes in a variety of hematologic and nonhematologic diseases arepresented.

2. The highest mean leukocyte fumarase values occurred in acute monocyticleukemia and acute granulocytic leukemia. Blast cells have greater fumaraseactivity than more mature forms of the same cell type.

3. Fumarase appears to be distributed ubiquitously among the various leukocytes. Cell populations which contained predominantly neutrophils, lymphocytes, monocytes, blasts, eosinophils, and basophils, all exhibited appreciableenzyme activity.

4. Assays of erythrocyte fumarase activity did not reveal a pattern with theexception of elevated values in macrocytic anemias and in some, but not all,cases of hemolytic anemia.

Submitted on August 22, 1960 Accepted on December 9, 1960