Effect of antiplague vaccination on phagocytic activity of human blood granulocytes

Abstract

Anti-plague vaccination stimulates phagocytosis of Yersinia pestis cells by blood leukocytes of laboratory animals. However its effect on the phagocytic activity of human white blood cells towards plague microbes has not been studied. In this work, flow cytometry was used to study phagocytic activity of blood granulocytes towards Y. pestis, Escherichia coli and Staphylococcus aureus in the people vaccinated, or not vaccinated against plague. These persons inhabited the territories of natural plague foci in Russian Federation. The results of phagocytic activity were evaluated in microvolumes of whole blood. The induced IFNγ production was evaluated in blood by enzyme immunoassay technique, and the titers of specific antibodies to plague-specific F1 antigen were determined in blood serum samples. It was found, that the subjects who have never been vaccinated against plague had 3-fold lower granulocyte phagocytic activity towards Y. pestis than the persons repeatedly vaccinated with live plague vaccine, and 5-fold lower than phagocytosis of E. coli and S. aureus. The next annual revaccination caused additional stimulation of in vitro phagocytic capacity of blood leukocytes with respect to plague microbes. Individual values of phagocytic indices correlated with serum antibody titers (r = 0.65, p = 0.0004), and with levels of IFNγ production (r = 0.73, p = 0.0004). Thus, the obtained data confirmed dependence between phagocytic activity of human blood leukocytes and the pathogen type, thus allowing to demonstrate a connection between activated phagocytic response to Y. pestis cells in live plague-vaccinated individuals with other immune indexes of vaccine efficiency (specific antibodies to F1, induced IFNγ production). Further research in this direction will bring us closer to development of an informative test for assessing the intensity of antiplague immunity.