Cytochemical demonstration of folic acid in normal and leukemic granulocytes

By means of an original cytochemical method, folic acid was demonstrated "in situ" in peripheral white blood cells in acute and chronic granulocytic leukemia. In control blood smears folic acid-relevant granules were found predominantly in the nuclei of neutrophils and basophils. Eosinophils were found positive for folic acid reaction both in nuclei and cytoplasm. In leukemic undifferentiated cells, less marked in acute than in chronic granulocytic leukemia, the cytoplasms contained a great quantity of folate. Nuclei were fewer or nonreactive. Therefore the cytochemical localization may be related to the degree of the white cells differentiation.