Eosinophilia, mast cell hyperplasia and antibody production in rats following an intraperitoneal injection of Ascaris cuticle including in-vitro studies of immune eosinophil granule lysis.

A single intraperitoneal injection of Ascaris cuticle caused a local eosinophilia with peak levels at 2 wk after injection. Mast cells reduced in number and size at 1 wk were found in increased numbers at 3 wk. Injection of a collagen-poor fraction of cuticle known as "cuticlin" resulted in a diminished eosinophil and mast cell response compared with injection of whole cuticle. Precipitating antibodies to soluble Ascaris cuticle collagen were detected in the serum and peritoneal fluid from day 5 onward. It is proposed that the eosinophilia and mast cell hyperplasia are the result of immunization of the animal to an antigen present in Ascaris collagen and rendered soluble by the action of mononuclear phagocytes. The eosinophil and mast cell response to Ascaris cuticle mimicked the response in connective tissue to living nematode parasites. It is concluded that the cuticle of nematode parasites may be responsible for eosinophilia and mast cell hyperplasia in the host.