Objective:To investigate the preparation,extraction and identification of exosomes(Dex) derived from the different maturity dendritic cells(DCs) in vitro. Methods:F344 rat bone marrow-derived DCs were cultured 6 days then divided into 2 groups,the immature dendritic cells group(immature DC,imDC):the supernatant was collect;the mature dendritic cells group(mature DC,mDC):the concentration of 1μg/ml of LPS was added,and after cultured for 48 hours,the supernatant was collected. The Dex was isolated by multi-step centrifugation. Flow cytometry was used to detecte Dex phenotype. Enzyme-linked immunoassay (ELISA) was used to detected the IL-10 and interleukin-12 (IL-12p70) levels of in the supernatant. Both groups of Dex were co-cultured with imDC derived from Wistar bone marrow. The co-cultured DCs ability to stimulate T cell proliferation was detected by mixed lymphocyte reaction(MLR). Results:Compared with exosomes secreted from mDc,the imDC secreted exosomes expressing moderate levels of MHC-Ⅱ,low levels of CD80,CD86,CD40. And it has a weak stimulation to IL-12p70 secretion after co-cultured with Wistar rat bone marrow-derived imDC(P < 0.05),as to as stimulation to T lymphocyte proliferation(P < 0.05). Conclusion:The exosomes secreted by different maturity of DCs have different functions,may play different roles in the host immune response.