VITAMIN B 12 CONTENT OF CIRCULATING LEUKOCYTES AS AN AID IN THE DIFFERENTIATION OF THE ACUTE LEUKEMIAS.

From 25 patients with acute leukemia 116 specimens of leukocytes were assayed microbiologically for total vitamin B(12) to determine if variation in vitamin B(12) content would help in differentiating the acute leukemias. The mean cell vitamin B(12) levels (mumug./10(8) cells) in the different types of leukemia were: lymphoblastic 464, myeloblastic 1058 and monocytic 200. Cell vitamin B(12) levels above the normal range (100-800 mumug./10(8) cells) are suggestive of myeloblastic leukemia. The only elevated cell vitamin B(12) levels comparable to those found in myeloblastic leukemia were in reticulum cell leukemia, and this type of leukemia was not difficult to diagnose morphologically. Blast cells contained more vitamin B(12) than mature cells of the same series; there was a significant positive correlation between the percentage of blast cells and cell levels of total vitamin B(12) in both lymphoblastic and myeloblastic leukemia.