Changes on lysosomal compartment during PMA-induced differentiation of THP-1 monocytic cells: Influence of type I and type IV collagens

""hesion during phorbol-12-myristate-13-acetate (PMA)- induced differentiation of THP-1 monocytic cell line was studied. In particular, by morphocytochemical and cytometric approaches, the influence of type I and type IV collagens in an experimental model rep- resentative of three phases (initial, intermediate and terminal) of monocyte-macrophage transition was analyzed. The cells in these three phases of differen- tiation were obtained by using 6, 30 e 60 nM PMA. In this experimental model, referring to adhesion to glass as control, by using the azo-dye coupling me- thod, we have considered the analysis of Acid Phos- phatase (AcP) activity as a marker of differentiated status expression, in relation to the acquisition of macrophagic phenotype. Endosomal\\\/lysosomal sys- tem was further characterized by taking in account the uptake of fluorescent probe LysoTracker Red. Fluorochromization in the various experimental con- ditions was analyzed morphologically (fluorescence microscopy) and quantitatively (static cytometry). Data related to lysosome compartment were integra- ted, from a cytokinetic point of view, by flow cy- tometry measurements of DNA\\\/protein content. Our results have indicated that type I and type IV colla- gens were able to influence, with respect to glass ad- hesion, various differentiation phases. Type I collagen showed the higher effects in the condition of high dif-ferentiation (60 nM PMA), causing an increase in AcP activity and lysosomal system. Type IV collagen, besides determining effects on lysosomal compart- ment of intermediate and terminally differentiated cells, influenced mainly proliferative activity of cells with initial differentiation level (6 nM PMA).""