Dendritic cells and interleukin-2: cytochemical and ultrastructural study

The aim of the present study was to verify the effect of IL-2 on dendritic cell (DC) differentiation. Various cytokines have been indicated as factors inducing DC differentiation, but no data about the interleukin-2 (IL-2) ef fect on DC differentiation have been reported. Monocytes isolated from peri pheral blood were treated in vitro with the following factors: IL-2, IL-4, GM-CSF and G-CSF alone or in combination. Morphological (also ultrastructur al) and cytochemical observations were carried out starting from 3 to 21 da ys of treatment. The results indicate that the differentiation of cells sho wing dendritic pattern is related to the presence of IL-2. Moreover a syner gic effect of IL-2 and GM-CSF was observed. The enzymatic features changed with the culture time: before the differentiation into DC, the stimulated c ells expressed the typical pattern of monocytes. On the contrary, at advanc ed stage of differentiation, some enzyme activities changed and in terminal ly differentiated dendritic cells the reactions for peroxidase and serine e sterase were negative. Considering the morphological features, the ability to interact with lympho cytes and the enzymatic pattern observed, we suppose that IL-2 may act as a maturative factor rather than as a growth factor in the DC differentiation .