Inflammatory markers in bronchoalveolar lavage fluid of standardbred racehorses with inflammatory airway disease: response to interferon-alpha.

Protein and eicosanoid concentrations and procoagulant activity were determined in bronchoalveolar lavage fluid (BALF) from 32 Standardbred racehorses with inflammatory airway disease (IAD) and 6 control horses. Total protein, albumin and immunoglobulin G (IgG) concentrations were high (P < 0.05) in the BALF from horses with IAD, a finding consistent with exudation of plasma protein into the airway. Immunoglobulin A (IgA) concentrations also were increased (P < 0.05) which may signify local immunoglobulin production. Difference was not detected in prostaglandin E2 and 6-ketoprostaglandin F1 alpha concentrations in BALF of IAD-affected and control horses. Procoagulant activity was identified in the majority (66%) of BALF samples from IAD-affected horses and was not detected in control horses. Natural human interferon-alpha (nHulFN alpha) (placebo, 50, 150, or 450 units) was administered orally for 5 days to IAD-affected horses in a double-blind, randomised block design. Total protein, IgG, and IgA concentrations in BALF were reduced (P < 0.05) 8 days after administration of 50 u and 150 u nHuIFN alpha, and 15 days after administration of 50 u nHuIFN alpha. Procoagulant activity and albumin concentrations in BALF were lower 8 days after administration of 50 u nHuIFN alpha. Oral administration of low-dose nHuIFN alpha appeared to ameliorate these parameters of lower respiratory tract inflammation in Standardbred racehorses with IAD.