Immune responses to antigens of in vitro reared Echinococcus granulosus adult worms in Balb/c mice

Abstract

Background: Cystic echinococcosis (CE), also known as echinococcosis/hydatidosis, is one of the most important parasitic diseases in the world. It enhances both humoral and cellular (Th1 and Th2) responses in infected host. Different antigens of the worm may favor the Th1 or Th2 immune responses in CE patients.

Objective: To evaluate the humoral and cellular immune responses of Balb/c mice against the crude and excretory/secretory (E/S) antigens of in vitro reared Echinococcus granulosus adult worms.

Methods: A total of 20 Balb/c mice divided into 5 groups of 4 mice each. Three groups of mice (n=4) were immunized with crude, E/S and an immunodominant antigen of in vitro reared Echinococcus granulosus adult worms on day 1 and 28. The fourth and the fifth groups were negative control groups and received PBS plus adjuvant, or nothing, respectively. Two weeks after the second injection, the mice were killed and their blood was collected for determining antibody responses, and their spleens were employed for proliferation assay. Total IgG was measured by indirect ELISA. Spleen cells of immunized mice were cultivated and exposed to different antigens of adult worms including E/S and crude antigens. Levels of IFN-γ, IL-12, IL-4 and IL-10 were measured in the recovered cell culture supernatants by capture ELISA.

Results: Total IgG assay showed the highest level of antibody produced in mice immunized with crude antigens. Proliferation assay showed a statistically significant production of cytokines in the mice immunized with crude antigens (p<0.05). The highest levels of IFN-γ, IL-12 and IL-4 were produced in mice immunized with crude antigen of the in vitro reared Echinococcus granulosus adult worms followed by E/S antigens. Immunodomonant antigen induced the lowest levels of cytokines (IL-12, IFN-γ, IL-4 and IL-10) in immunized mice.

Conclusion: Significant levels of Th1 related cytokines (IFN-γ and IL-12) were produced in Balb/c mice immunized with crude antigen of the in vitro reared Echinococcus granulosus adult worms.