Influence of immunomodulation on intracellular cytokine expression by spleen T-helpers of mice immunized by Yersinia pestis EV NIIEG

Aim . To characterize the intracellular expression of cytokines by spleen T-helpers and the spontaneous production of cytokines in the blood of BALB/c mice immunized with Yersinia pestis EV NIIEG against the background of immunomodulation. Materials and methods . Intracellular expression of CD4 + IFN-γ + , CD4 + IL-4 + , CD4 + IL-17 + was determined in mice spleen cell suspensions by flow cytometry, IFN-γ and IL-10 were measured in ELISA in blood supernatants on day 3 and day 21 after the immunization with Y. pestis EV against the background of immunomodulation. On day 21 after the immunization animals were infected by Y. pestis 231 at a dose of 400 LD50. Results . Differences in cytokine response to studied drugs, correlated with CD4 + IFN-γ + levels in animals, were identified. On day 3, a significant decrease in CD4 + IFN-γ + was observed in response to Y. pestis EV and to recombinant gamma interferon (Ingaron). A significant increase in CD4 + IFN-γ + was detected in response to vaccine strain administered with azoximer bromide (Polyoxidonium). Intracellular expression of IFN-γ, IL-4 and IL-17 increased on day 21by an average of 2,3 times when immunomodulators were used in the immunization schedule. In addition, on day 21 a significant (p ˂ 0.05) increase in the proportion of T-helpers expressing IFN-γ, as well as in level of spontaneous IFN-γ production in blood supernatants was observed only in animals immunized by schedules that included immunomodulators. After the challenge with Y. pestis 231 of animals previously immunized by schedules that included Polyoxidonium, the correlation analysis confirmed the association (r = 0,94; p = 0,0004) of mice survival with intensity of CD4 + IFN-γ + expression. Conclusion . The data obtained confirm the effectiveness of Polyoxidonium application in experimental animal Y. pestis EV immunization schedule and the usefulness of intracellular cytokine expression measurement for assessment of the level of protection following the immunization.