The response of mouse macrophage cell line infected with BCG in vitro

Abstract:

Abstract：[Objective] To illuminate the response of mouse macrophage cell line RAW264.7 after infected with Bacille Calmette-Guerin (BCG) in vitro. [Methods] We analyzed the morphology and expression of co-stimulatory molecules on the surface of RAW264.7 after exposed to BCG for 23 hours. Then during the different culture time after discard the BCG in the supernatant, we analyzed the response of RAW264.7 by flow cytometry using carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE), annexin V/PI and Rhodamine 123, respectively. [Results] We observed the phagosome containing BCG under transmission electronic microscope and RAW264.7 cells still grow well after incubated with BCG for 23 hours. We found that the expression level of co-stimulatory molecules, CD40, CD54, CD80, CD86 and CD11b, were elevated evidently, except CD11c, I-Ad and H-2Kd. The fluorescence intensity of BCG stained with CFDA-SE decreased with the prolongation of culture time, but it was still more higher than unstained control four days later. After removal of uninfected BCG, the percents of BCG-infected cell decreased and we didn’t detected BCG-infected cells evidently for 60 h culture. Furthermore, we also found that there was no obvious cell apoptosis for all the time, and the mitochondrial membrane potential of BCG-infected cells increased early and then decreased to the same level as the uninfected control. [Conclusion]These results would be helpful to elucidate the mechanism of BCG vaccination.