Aim: Since cellular maturation largely depends on lipid metabolism, we examined whether L-carnitine (L-C), a substance involved in these biochemical pathways, is able to promote differentiation of the promyelocytic cell line HL-60.
Methods: Differentiation was assessed by marker analysis, morphology, immunohistochemistry, proliferation and cellular activity assays.
Results: L-C increases HLA-DR and CD14 surface antigens, while morphologic and marker analysis of the treated cells reveals the presence of monocytes, neutrophiles and few dendritic cells. What is important, however, is the induction of cells that have an atypical to this pathway allure staining positive for the neurofilament 3A10 monoclonal antibody, specific for nerve cells and the anti-p75 (Nerve Growth Factor Receptor) monoclonal antibody. The events described concern active and, at the same time, not proliferative senescent cells.
Conclusions: L-C exerts its differentiation action on a certain fraction of the leukemic population yielding a non-negligible number of atypical for the myeloid lineage cells. These findings complement earlier and recent reports that describe the generation of cells of a different lineage irrelevant to their parent line of differentiation indicating that the hemopoietic pool appears to be the source of any kind of cell types according to the stimulus provided. Thus, in the context of the plasticity theory it appears that the HL-60 cell line also possess the potential to differentiate towards unexpected pathways.