lactoferrin and Leukemia--Monocytic--Acute

We examined the activity of bovine lactoferricin (Lfcin-B), a peptide derived from a bovine milk protein lactoferrin (LF-B), to induce apoptosis in THP-1 human monocytic leukemic cells. Treatment with Lfcin-B at up to 50 micrograms/ml induced cell death in THP-1 cells in dose- and time-dependent manner, showing apparent morphological changes, hypodiploid forms of genomic DNA and apoptotic DNA fragmentation, whereas LF-B was inactive even at a high dose (500 micrograms/ml). The apoptosis-inducing effect of Lfcin-B increased with reduction of serum concentration, but was inhibited by addition of Zn2+, a inhibitor of Ca2+/Mg(2+)-dependent endonucleases in a dose-dependent manner. Furthermore, Lfcin-B-induced apoptosis in THP-1 cells was completely abolished by addition of antioxidants such as N-acetyl-L-cysteine (NAC) and glutathione (GSH), but not by various cytokines and mitogen which can activate monocytic cells. In addition, THP-1 cells treated with Lfcin-B, but not LF-B, showed high levels of intracellular reactive oxygen species (ROS) from the early period (20 min) of Lfcin-B treatment. And the production of ROS by Lfcin-B was dependent upon the dose of Lfcin-B added. These results suggested that Lfcin-B, a LF-B-derived peptide, but not LF-B itself, is able to induce apoptosis in THP-1 human monocytic tumor cells, and that its apoptosis-inducing activity is related to the pathway mediated by production of the intracellular ROS and activation of Ca2+/Mg(2+)-dependent endonucleases.

Topics: Acetylcysteine; Animals; Apoptosis; Cattle; Diploidy; DNA Fragmentation; DNA, Neoplasm; Female; Glutathione; Humans; Kinetics; Lactoferrin; Leukemia, Monocytic, Acute; Milk; Reactive Oxygen Species; Tumor Cells, Cultured

Samples from 49 cases of myeloproliferative diseases were tested by an immunocytochemical technique for leucocyte lysozyme and lactoferrin. The presence of these constituents in myeloid precursors from cases of acute and chronic myeloid leukaemia reflected the degree of cellular maturation, lysozyme appearing (as it does in normal myeloid cells) at the stage of primary granule production (in promyelocytes), while lactoferrin wad detectable only in more mature, secondary granule-containing myeloid cells. Auer rods stained positively for lysozyme, in keeping with their relationship to primary granules. Monocytes from five cases of leukaemia showing predominantly monocytic differentiation were indistinguishable from normal monocytes in their staining reactions for lysozyme despite the presence of raised serum and urinary lysozyme levels. In four cases of acute myeloid leukaemia circulating polymorphs deficient in lactoferrin were detected: in one of these cases a similar percentage of polymorphs was lysozyme negative.

Topics: Humans; Immunoenzyme Techniques; Intracellular Fluid; Lactoferrin; Lactoglobulins; Leukemia, Monocytic, Acute; Leukemia, Myeloid, Acute; Leukocytes; Monocytes; Muramidase; Myeloproliferative Disorders; Neutrophils