Cytokine Concentrations in Bronchoalveolar Lavage Fluid from Horses with Neutrophilic Inflammatory Airway Disease

BackgroundMultiple cytological patterns occur in bronchoalveolar lavage fluid (BALF) of horses with inflammatory airway disease (IAD). Only few data on BALF cytokine profiles are available for horses with IAD, and are limited to mRNA expression. Hypothesis/ObjectiveCytological profiles of IAD are associated with different BALF immunological pathways. To investigate BALF cytokine concentrations in a large number of horses with neutrophilic IAD. AnimalsOne hundred and thirty-eight client-owned Standardbred racehorses in active training. MethodsProspective observational study. BALF samples were obtained from left and right lungs. Interleukin (IL)-4, interferon (IFN)-, and tumor necrosis factor (TNF)- concentrations were determined by ELISA. ResultsFourteen horses had normal BALF cytological profiles and 56 exhibited evidence of bilateral neutrophilic IAD. Twenty-four horses showed BALF with, respectively, IAD- and CTL consistent cytology and were excluded; as were 44 horses because of evidence of pulmonary hemorrhage. TNF- (56115pg/mL; P=.034) and IFN- concentrations (104 +/- 247pg/mL; P=.044) were significantly higher for IAD horses, compared with controls (respectively 19 +/- 41 and 80 +/- 116pg/mL). Horses with neutrophil' subtype had significantly higher IFN- concentrations (110 +/- 154pg/mL), than neutrophil/metachromatic' (56 +/- 54pg/mL; P=.028) and neutrophil/metachromatic/eosinophil' subtypes (44 +/- 23pg/mL; P=.012). Conclusions and Clinical ImportanceCytokine concentrations in BALF suggested that neutrophilic IAD is associated with activation of the innate immune system and a possible T-helper (Th)-1 polarized response. This study also suggested that immunological pathways vary according to cytological IAD subtypes.