Abstract: Objective To investigate the adaptive changes of morphology and cytoskeleton of the dendritic cells （DC） before and after lipopolysaccharide（LPS）-induced maturation. Methods The murine bone marrow mononuclear cells were induced into immatured dendritic cells（imDC） with granulocyte -macrophage colony -stimulating factor（GM-CSF） and interleukin（IL）-4, after 6 days imDC were further induced into matured DC（mDC） with LPS for 48 hours. These DC morphology was observed under fluorescent microscope and inverted phase contrast microscope（IPCM）, and the changes of cytoskeleton between imDC and mDC were compared. Results mDC expressed higher level of CD11c, MHC-Ⅱ, CD86 compared with imDC via flow cytometry. After LPS stimulation, the DC
became a little bigger. The external dendrites had obvious changes from thin, short（imDC） to thick, long（mDC）, finally thin, short again. Filament-actin（F-actin） was mainly focused on cytomembrane and dendrites. The mean
fluorescence of F-actin in cytomembrane and dendrite was the highest after 24 hours stimulated with LPS, but decreased apparently after 48 hours stimulated with LPS, and this time the F-actin in cytoplasma became sparse and
fragmentarypartially. Conclusion During the maturation, DC became more and more large with number, length and consistence of surface processes improved gradually, which helps to augment surface of cell and play the important
role of translation and presentation of antigen. Gradually largened nucleolus suggested that it maybe play a very important role in the translation and presentation of antigen. Within the progress of maturation, cytoskeleton,
such as F-actin, gave a closed cooperation via gradually increased number.

Key words: dendritic cell, lipopolysaccharide, cytoskeleton, filament-actin