In vitro modulation of preleukemic AKR mouse macrophage function by bacterial immunomodulators

Methionine enkephalin suppresses metabolic activity of a leukemic cell line (NALM-1) and enhances CD10 expression

NALM-1 cells (a cell line derived from human pre-B leukemia) were exposed to the opioid pentapeptide methionine-enkephalin (Met-enkephalin) and/or to thiorphan, an inhibitor of the enzyme that degrades the enkephalins (membrane endopeptidase EC 3.4.24.11, CALLA, the CD10 marker). Metabolic and proliferative activity was assessed after 6, 24 and 48 h in microplates using a colorimetric assay with vital dye MTT. CD10 expression was determined by means of semi-quantitative RT-PCR. Exposure to the Met-enkephalin at concentrations of 10(-8)-10(-6) M for 6 h reduced the MTT-activity, and after 24 and 48 h the suppression waned. Thiorphan (5 x 10(-6) M) abrogated the suppressive effect of the enkephalin, and after 6 h converted suppression into stimulation. Met-enkephalin (10(-6) M) increased and thiorphan (2.5 x 10(-6)-10(-6) M) decreased expression of CD10 at the RNA level. Suppression of the MTT uptake was attributed to the products of Met-enkephalin degradation caused by the enzymatic activity of CD10.

The effect of opioid agonists of delta-class DSLET, mu-class DAMGO, kappa-class U-69593 and an opioid antagonist, naloxone, on MTT activity of NALM-1 leukemic cells

The effects of synthetic agonists of delta-, mu-, kappa-opioid classes were studied on the proliferation of NALM-1 leukemic cells, using the MTT-test. Delta-opioid DSLET and mu-opioid DAMGO mildly and transiently decreased, in higher concentrations, the MTT-activity of NALM-1 cells after 6 h of treatment. The kappa-opioid agonist U-69593 mildly suppressed proliferation of NALM-1 cells after 48 h of treatment. Naloxone, an opioid receptor antagonist, mildly and transiently diminished MTT-activity of NALM-1 cells after 6 h of treatment. Treatment with opioid agonists, DAMGO, DSLET, U-69593, and an opioid antagonist naloxone for 6, 24, and 48 h, did not trigger DNA fragmentation, which was considered as a possible mechanism of action.

Activity of sympathoadrenal system and myelokaryocyte death during aging in AKR/JY mice

Accelerated bone marrow cell death and activation of the sympathoadrenal system were observed during aging of highly leukemic 2-7-month-old AKR/JY mice compared to that in (CBA/CaLacxAKR/JY)F1 strain. Close correlation was revealed between activity of the sympathoadrenal system and necrotic and apoptotic forms of cell death. This can promote tumor process, because maximum changes in hemopoietic cells occur during advanced stage of the disease.