Antibody‐dependent in‐vitro cytotoxicity of newborn Trichinella spiralis larvae: nature of the cells involved

Abstract

The cytotoxic reaction of normal peritoneal mouse cells, containing less than 3% eosinophils, against newborn Trichinella spiralis larvae, in the presence of antibody, was studied using newborn worms less than 2 h of age, or newborn worms that had been maintained in culture at 37 degrees C for 20 h. Newborn worms 2 h old were killed, whereas 20 h newborn worms were not. The cells that initially adhered to the larvae were examined by electron microscopy. Only eosinophils adhered to 2 h newborn worms and only macrophages to 20 h ones. The attached eosinophils degranulated and died after a few hours. The macrophages that adhered to, but did not kill the 20 h newborn worms were morphologically in good state and no lysis of the larvae was observed. These results suggest that different antibody classes are involved in eosinophil and macrophage adherence, and strongly support the hypothesis that eosinophils mediate larval destruction. They also show that rapid changes are taking place after birth in the structure of the larval cuticle and that the age of Trichinella newborn worms is a major factor in the antibody-dependent cellular cytotoxicity reaction.

Eosinophils and Trichinella infection: toxic for the parasite and the host?

“…This observation supports the hypothesis that eosinophils are cytotoxic versus the larval stage in mice [48,49]. Mouse eosinophils adhere to and kill T. spiralis newborn larvae in an antibody-dependent cellular cytotoxicity system [49] ( Figure 2 and Figure 3). …”

“…Worm burdens in the skeletal muscle were increased and the frequency of encysted larvae that exhibited necrosis was reduced in CCR3-deficient mice, compared with wild-type mice, during a primary infection [14]. This observation supports the hypothesis that eosinophils are cytotoxic versus the larval stage in mice [48,49]. Mouse eosinophils adhere to and kill T. spiralis newborn larvae in an antibody-dependent cellular cytotoxicity system [49] ( Figure 2 and Figure 3).…”

Mouse Mast Cell Tryptase mMCP-6 Is a Critical Link between Adaptive and Innate Immunity in the Chronic Phase ofTrichinella spiralisInfection

“…Previous analyses in IgE-deficient mice and in IgE-depleted rats demonstrated the importance of the adaptive immune response in clearance of T. spiralis from skeletal muscle (29,47). Because the mouse eosinophil does not express the highaffinity IgE receptor, this dependence implicated either mast cells in this process based on their expression of the high-affinity IgE receptor (although no direct assessment of mast cells around the lesion was performed) or antibody-dependent cytotoxicity by the eosinophil based on killing of newborn larvae in vitro (31). We herein extend those studies and show that mast cells are recruited to the site of larval infection, and that mMCP-6 Ϫ/Ϫ mice, like IgE Ϫ/Ϫ mice, exhibit profound decreases in eosinophil recruitment to T. spiralis larvae despite an intact humoral IgE response.…”

“…IgE also contributes to the immune response to larval presence through a mechanism not fully understood, although activation of mast cells found in the skeletal muscle has been hypothesized (29). Mouse eosinophils are not thought to express the high-affinity IgE receptor; however, eosinophil activation via antibody-dependent cytotoxicity is not excluded and has been suggested by in vitro studies (31).…”

Contrasting roles for IL‐10 in protective immunity to different life cycle stages of intestinal nematode parasites

“…In summary, the data presented here demonstrate that IFN-+ is crucially involved in protection against newborn larvae, but does not affect the expulsion of adult worms. Mechanisms of IFN-+ -mediated immunity to newborn larvae may include enhanced cytotoxic killing by eosinophils, granulocytes and activated macrophages [45][46][47][48][49].…”