A 21.6 kDa tegumental protein of Clonorchis sinensis induces a Th1/Th2 mixed immune response in mice.

INTRODUCTION: Clonorchis sinensis is a major parasite affecting the Korea population. Despite the high infection rate and pathogenicity, very few studies have been conducted to investigate the immune responses against the proteins of C. sinensis.

METHODS: In this study, in vitro immune response induced by a recombinant 21.6 kDa tegumental protein derived from C. sinensis (rCsTegu21.6) was confirmed in murine dendritic cells and T cells. For the in vivo analysis, each mouse was immunized three times. Total serum IgG and T cell cytokine production were determined by ELISA, while T cell proliferation was detected by a WST (Water-Soluble Tetrazolium salt)-1 assay.

RESULTS: In vitro tests indicated that rCsTegu21.6 treatment increased the expression of surface molecules, such as CD40 (77%), CD80 (52%) and CD86 (46%), on murine dendritic cells and the secretion of cytokines (TNF-α, IL-6, IL-1β, IL-10, and IL-12p70). Moreover, co-culturing dendritic cells activated by rCsTegu21.6 with allogenic T cells induced T cell proliferation over time. rCsTegu21.6 also stimulated specific antibody production and cytokine secretion [IL-2, IL-4, and interferon (IFN)-γ)] from T cells following immunization in vivo. Notably, rCsTegu21.6 predominantly induced IgG1 production and secretion of the Th2 cytokine IL-4, regardless of the type of adjuvant used.

CONCLUSION: These results serve as a foundation for the development of tegumental protein-based vaccines against C. sinensis.