Phenotypic analysis of peripheral blood and bronchoalveolar lavage fluid lymphocytes in control and chronic obstructive pulmonary disease affected horses, before and after 'natural (hay and straw) challenges'.

Phenotypic analysis of lymphocytes in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) of control and chronic obstructive pulmonary disease (COPD) affected horses, both before and after 'natural (hay and straw) challenge', were performed using immunofluorescent labelling with monoclonal antibodies and flow cytometry. BALF lymphocytes were shown to be predominantly EqCD5+ cells, approximately half of which were also EqCD8+, with a smaller proportion of B cells. In comparison with PB, BALF contained higher proportions of EqCD5+ cells and EqCD8+ cells and a lower proportion of B cells. Horses with asymptomatic COPD had a higher proportion of BALF B cells and a lower proportion of BALF EqCD5+CD8- cells (considered to be predominantly EqCD4+ cells) than controls. Hay and straw challenge increased the ratio of BALF EqCD5+CD8- cells and reduced the ratio of BALF EqCD8+ cells in COPD affected horses, but not in controls. This finding is similar to the pulmonary recruitment of CD4+ cells reported for human asthmatics following allergen challenges.