Effect of the Monocyte Locomotion Inhibitory Factor (MLIF) a Natural Anti-Inflammatory Produced by E. Histolytica on Apoptosis in Human CD4 + T Lymphocytes

Apoptosis prevents the extravasation of intracellular material and the subsequent inflammatory response. Currently, it is not known whether Monocyte Locomotion Inhibitor Factor (MLIF), an anti-inflammatory pentapeptide, induces programmed cell death. We evaluated the effect of MLIF on extrinsic and intrinsic apoptosis pathways human CD4 + T lymphocytes. Cells were cultured for 24 h in RPMI-1640 medium alone (control) or in RPMI medium containing MLIF alone, PMA alone, PMA + MLIF or actinomycin D. Annexin V/propidium iodide-stained cells in early apoptosis showed that cells treated with MLIF or PMA + MLIF were not significantly different from control cells in medium; in contrast, cells treated with PMA or PMA + MLIF demonstrated significant differences from the control in delayed apoptosis. Cytochrome c and caspase 3 levels in cells treated with MLIF showed no significant differences from control cells, however, compared to the control, cells treated with PMA and PMA + MLIF exhibited a significant increase in cytochrome c and caspase 3 levels, which demonstrates that this weak induction of cell death is regulated by the intrinsic pathway of apoptosis. The Fas receptor was not detected in cell culture with any of the treatments employed, suggesting that the extrinsic pathway of apoptosis is not involved. The MLIF per se does not induce apoptosis in human CD4 + T lymphocytes; there may be an additional effect of PMA + MLIF producing the low levels of cell death recorded in the late apoptosis phase. MLIF acts as a natural, biological anti-inflammatory compound produced in axenic cultures of E. histolytica that does not cause apoptosis or elicit an immune response due to its small size, which could make it a strong candidate for future clinical applications.