Role of Leukotrienes on Protozoan and Helminth Infections
Figure 3
Modulation of innate and adaptive immune responses during the helminth infections. Initial exposure of the immune system to parasitic antigens leads to the activation of a subset of T cells known as Th2 cells, which orchestrate the immune response to these exogenous antigens by secreting cytokines, including IL-4, IL-5 and IL-13. The accumulation of eosinophils in the blood and in different organs and tissues as well as the degranulation of IgE-sensitized mast cells is hallmarks of helminthiasis. Eosinophils and mast cells are sources of LTs. (A) CysLTs are required for molting of the infectious larvae (e.g., Brugia malayi larvae). (B) CysLTs, alone or in conjunction with Th2 cytokines, cause contractility of smooth muscle cells, the permeability of epithelial cells, and the production of mucus, thereby contributing to worm expulsion. (C) LTB4 recruits and activates inflammatory cells such as eosinophils to favor the kill of helminths. (D) LTB4 regulates IL-5 production by human T lymphocytes and consequently contributes to parasite elimination. (E) LTB4 induces chemotaxis of CD4+ T cells.
