CELLULAR AND CHEMICAL MEDIATORS OF TYPE-1 HYPERSENSITIVITY IN CALVES INFECTED WITH OSTERTAGIA-OSTERTAGI - HISTAMINE, PROSTAGLANDIN-D2, PROSTAGLANDIN-E2 AND LEUKOTRIENE-C4

Plasma histamine, prostaglandin (PG) D2, PGE2, and leukotriene (LT) C4 levels were determined in 26 Holstein steers before and after natural or experimental infection with Ostertagia ostertagi. Post-infection a bomasal lymph was also assayed for PGD2, PGE2, and LTC4. Histamine det erminations were performed on abomasal tissue from three locations. Re sults showed that: (1) tissue histamine levels increased in steers wit h type 2 ostertagiosis, (2) lymphatic PGD2 and PGE2 levels were increa sed, probably as a result of macrophage activity, (3) lymphatic LTC4 l evels increased in steers with type 1 ostertagiosis, and were correlat ed with tissue eosinophilia, and (4) plasma levels of PGD2, PGE2, LTC4 and histamine were not useful for predicting worm burdens. These find ings suggest a functional role for eosinophils and mast cells in the p athophysiology of ostertagiosis, through mediation of a type 1 hyperse nsitivity reaction.