EVALUATION OF HUMORAL AND CELLULAR IMMUNITY LEVEL AMONG PERSONS LIVING IN THE CASPIAN NATURAL SANDY FOCUS TERRITORY AFTER ANTI-PLAGUE REVACCINATION

In view of increasing epidemic danger potential of some natural plague foci and performing measures to provide specific prevention of this infection, it becomes necessary to carefully monitor the state of immunity in vaccinated (revaccinated) individuals. The aim of the study was to assess humoral and cellular immunity levels in the persons after repeated anti-plague revaccination performed for appropriate epidemiological indications. Evaluation of immune responses to anti-plague revaccination was carried out according to studies of blood samples from 20 people aged 24 to 53 years living in the Caspian sandy natural plague focus located at the territory in Kalmykia Republic. Specific antibody titers to the F1 antigen of plague microbe were assessed in blood serum by immunoassay testing using an “ELISA-AT-F1 YERSINIA PESTIS” test system (Russian Research Anti-Plague Institute “Microbe”, Russia), along with spontaneous and concanavalin A-induced production of different cytokines, i.e., IFNγ, TNFα, IL-4, IL-10 (Vector-Best, Russia), IL-17A (Bender Medsystems, Austria). The studies were performed before vaccination, and 1, 6, 12 month after the booster vaccination.The results of the study indicate that immunological reconstitution after revaccination with live plague vaccine occurs occurred mostly according to mixed Th1/Th2 type. Detection of antibodies to the F1 specific plague microbe antigen before and 1 month after revaccination (65 and 85%, respectively) was indicative of development of humoral response. The most informative cytokine markers (IFNγ and TNFα) for evaluation of an anti-plague cellular immune response have been identified. The threefold increase in IFNγ induced production before revaccination indicates to initial immunological competence of all the examined individuals. A high correlation between TNFα and other cytokine levels was determined. The fact of high correlation for the studied cytokines (TNFα, IFNγ, IL-10) indicated to a synchronism in the immunocompetent T helper cell reaction. By measuring the levels of spontaneous and induced cytokine production levels, one may indirectly judge on degree of anti-plague cell immunity in humans