Possible cell recruitment in human leukaemia

Lymphocyte stimulation by soluble subcellular fractions

Nuclear material can produce inhibition or stimulation of healty leucocytes under different experimental conditions, Reactivity could not be produced in cultures using intact nuclei and allogeneic lymphocytes. The effect of nuclear and cytoplasm fractions was compared with that of whole cells on intact healthy lymphocytes. The HLA activity in the individual fractions was assessed. Stimulation was produced by certain nuclear and cytoplasmic fractions and these were closely related to the peaks of HLA activity. The response to these fractions showed less activity than that achieved in conventional one way MLC tests.

[Pharmakokinetics of hydroxy-urea. Therapy of acute myeoblastic leukemias using synchronization and recruitment effects (author' transl)]

By a plasma-concentration of hydroxy-urea (HU) higher than 0.5-2.2x10(-4)M the DNA-synthesis in leukemia cells was blocked reversibly in 9 patients. The plasma half-time of HU varied between 120 and 198 min. To synchronize leukemic cell populations the DNS-synthesis was blocked over a period of 36 hours by maintaining the HU-concentration above the critical lower level. In a second phase-specific therapeutic step cytosine-arabinoside (AraC) was given 4 times in a dose of 1 mg/kg each. A recruitment after the application of AarC made more cells available for the next following synchronization step. 4 acute myeloblastic leukemias with high peripheral cell counts were treated according to this schedule. One patient is still in complete remission for now 14 month. This synchronization/recruitment schedule seems to be successful in acute myeloblastic leukemias with high proliferation rates measured by biochemical and cytokinetic methods.