Equid herpesvirus 1: platelets and alveolar macrophages are potential sources of activated TGF-B1 in the horse.
Cell mediated responses to Equid herpesvirus 1 (EHV-1) are of short duration in vivo and require considerable expansion to be detected in vitro. Raised serum levels of active transforming growth factor B (TGF-B1) have been shown to depress proliferative T cell responses in experimental infections with EHV-1 in ponies. The present work indicates that latent transforming growth factor B (TGF-B1) is present in circulating platelets, lymph node, bronchial epithelium and alveolar macrophages. Activation of platelets in vitro by thrombin resulted in the release of latent TGF-B1 from platelets, with a pg level of conversion to active TGF-B1, but virus alone did not activate TGF-B1. Exposure of circulating leucocytes to EHV-1 in vivo or in vitro does not result in detection of active TGF-B1 above residual levels that could be attributed to activation of platelets by manipulation. However, alveolar macrophages obtained by lavage at autopsy yield both latent and active TGF-B1 in ng quantities. Bronchial epithelium, and mesenteric lymph node leucocytes had equivalent levels of latent TGF-B1, but horses varied as to whether these tissues were a source of activated TGF-B1 and as to whether EHV-1 activated TGF-B1.
Chesters
P M
PM
Royal Veterinary College, Royal College Street, NW1 0UT, London, UK.
Hughes
A
A
Edington
N
N
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D018893:Bronchoalveolar Lavage; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D006566:Herpesviridae Infections / Q000378:metabolism*; D004861:Herpesvirus 1, Equid; D006734:Horse Diseases / Q000378:metabolism* / Q000821:virology; D006736:Horses; D016676:Macrophages, Alveolar / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*
D016212:Transforming Growth Factor beta