Objective To explore the differential expression of the key microfilament cytoskeleton-binding proteins in immature dendritic cells(imDCs)during antigen phagocytosis.Methods Monocytes(MOs)were isolated from peripheral blood of healthy individuals and cultured with recombinant human granulocyte-macrophage colony stimulating factor(rhGM-CSF)and recombinant human interleukin-4(rhIL-4)for 6 days to obtain imDCs.ImDCs were co-cultured with low molecular weight(40 kDa)and high molecular weight(150 kDa)dextrans for 1,3 and 6 hours,respectively.Flow cytometry was used to detect the percentage of imDCs phagocytosing dextran and the expression of immunophenotype molecules.The localization of filamentous actin(F-actin),PFN1,WASP,and α-actinin in cells were observed by immunofluorescence imaging.The differential expression of MCBPs at the mRNA and protein levels were respectively detected by q-PCR and Western blotting.Finally,the MCBPs with the highest component coefficients were identified based on the stepwise regression and principal component analysis method in systems biology algorithms.Results During the process of antigen phagocytosis,imDCs phagocytized low molecular weight antigens at a faster rate,with a phagocytic duration of approximately three hours.Their cell phenotypes and morphology gradually differentiated into mDCs,and F-actin remodeling was occurred significantly.The expression of MCBPs such as PFN1,CDM,WASP,CAPZB,Filamin A,α-actinin were downregulated,while the expression of WAVE1,Arp2/3 complex,and Fascin were upregulated.The mRNA expression of signaling protein Rac1 was upregulated,while the mRNA expressions of CDC42 and RhoA were downregulated.The immunofluorescence results showed that PFN1,WASP,and α-actinin were transposed during the antigen phagocytosis process of imDCs.The results of stepwise regression and principal component analysis showed that PFN1 had the highest component coefficient.Conclusions PFN1 may be a key MCBPs involved in the process of antigen phagocytosis of imDCs,which is of great significance for further understanding the relationship between changes in the cytoskeleton structure of imDCs and their immunological functions.