Predominance of IL-10 and TGF-β production from the mouse macrophage cell line, RAW264.7, in response to crude antigens from Clonorchis sinensis.

Parasitic helminths are well-known to have the ability to modulate host immune responses. In this study, we investigated the fundamental immunoregulatory mechanism of the liver fluke Clonorchis sinensis (C. sinensis) using a murine macrophage RAW 264.7 (RAW) cell line and mouse bone marrow derived macrophages (BMDMs). We found that C. sinensis crude antigen (CA) is able to differentiate macrophage RAW cells into dendritic-like cells that can be detected by morphological observations. In addition, CA induces prominent secretion of anti-inflammatory cytokines such as IL-10 and TGF-β; however, we did not observe changes in cell surface markers that are involved in antigen recognition, antigen presentation, and T cell activation. Additionally, CA treatment induced ERK and JNK phosphorylation, and unexpectedly, elevated levels of IL-10 and TGF-β were inhibited by the addition of an ERK-specific inhibitor. Taken together, these data demonstrate that CA from C. sinensis may modulate host immune responses by upregulating anti-inflammatory cytokines via the regulation of ERK.