Exogenous double-stranded DNA induces immunophenotypic changes of bone marrow-derived dendritic cells

Objective To study the effects of exogenous double-stranded DNA antigen on the immunophenotypic changes of dendritic cells (DCs) derived from stem cells in mouse bone marrow. Methods LinCD117 (c-kit)+ hemopoietic stem cells were obtained from the bone marrow of C57 mice by magnetic affinity cell sorting. Some cytokines, including granulocyte-macrophage colony-stimulating factor, interleukin-4, tumor necrosis factor-α and so on, were used to enhance the proliferation or differentiation of stem cells to obtain mature, semimature and immature DCs. The double stranded DNA of kinetoplast (kDNA) was isolated from Trypanosoma equiperdum, and added to the culture media to pulse DCs. The immunophenotypic and morphologic features of DCs were analyzed by using flow cytometry and laser confocal microscopy respectively. Results The expression rates of CD117 and CD11c in DCs showed no significant changes after kDNA pulse compared with those before the pulse. In unpulsed immature, semi-mature and mature DCs, the expression rate was 11.42% ± 2.56%, 27.08% ± 5.29% and 44.63% ± 10.37% for MHC Ⅱ, 8.54% ± 2.01%, 31.35% ± 6.40% and52.96% ± 10.34% for CD80, 10.22% ± 3.47%, 32.15% ± 6.83% and 64.72% ± 9.68% for CD86, respectively.After pulse with the kDNA antigen, the expression rate increased by 15.63%, 9.66% and 4.12% (t = 6.21,4.35, 2.82, P < 0.05) for MHC Ⅱ, by 9.63%, 7.09% and 4.09% for CD80, by 13.16%, 9.75% and 3.10% for CD86, respectively in immature, semi-mature and mature DCs, respectively. The increase of expression rate of these membrane antigens in decreasing order was observed in immature DCs, semi-mature DCs and mature DCs. Conclusions The exogenous DNA antigen could enhance the maturation of bone marrow-derived DCs,likely by upregulating the expression of certain immunophenotypic membrane proteins, and the lower the maturity degree, the more liable the DCs to be affected by the antigen. Key words: Connective tissue diseases; Antibodies,anti-double stranded DNA; Dendritic cells; Immunophenotyping