title: Trypanosoma theileri associated with T-lymphocytes isolated from a latently infected cow.
abstract: Trypanosoma theileri infection, latent in a mature Hereford cow, could not be demonstrated in routine blood smears or cultures. Throughout the 2-year period an intravenous injection of dexamethasone consistently produced parasitaemia which was detectable in peripheral blood mononuclear cell (PBMC) cultures. Fractionation techniques such as plastic adherence and Sephadex-G10 fractionation, designed to deplete monocytes and enrich T-lymphocytes, increased trypanosome-positive cultures from 25 to 100%. Removal of B-lymphocytes from Sephadex, non-adherent (SE-NA) cells did not reduce the percentage of positive cultures. Light and transmission electron microscopy of SE-NA PBMC cultured for 36 or 45 h revealed numerous trypanosomes and widespread T-lymphocyte destruction. No trypanosomes were observed in 12-h cultures. A close association, either extra- or intracellular, of a parasitic stage of T. theileri with T-lymphocytes is inferred.
authors: Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
authors: P J
authors: PJ
authors: Griebel
authors: A A
authors: AA
authors: Gajadhar
authors: L A
authors: LA
authors: Babiuk
authors: J R
authors: JR
authors: Allen
mesh_terms: D000818:Animals; D001402:B-Lymphocytes; D002417:Cattle; D003470:Culture Media; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D013601:T-Lymphocytes / Q000469:parasitology* / Q000648:ultrastructure; D014345:Trypanosoma / Q000187:drug effects / Q000302:isolation & purification; D014354:Trypanosomiasis, Bovine / Q000469:parasitology*
chemical_list: D003470:Culture Media; D003907:Dexamethasone