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 bronch oalveolar lavage fluid (BALF) of control and chronic obstructive pulmo nary disease (COPD) affected horses, both before and after 'natural (h ay and straw) challenge', were performed using immunofluorescent label ling with monoclonal antibodies and flow cytometry. BALF lymphocytes w ere shown to be predominantly EqCD5+ cells, approximately half of whic h were also EqCD8+, with a smaller proportion of B cells. In compariso n with PB, BALF contained higher proportions of EqCD5+ cells and EqCD8 + cells and a lower proportion of B cells. Horses with asymptomatic CO PD had a higher proportion of BALF B cells and a lower proportion of B ALF EqCD5+CD8- cells (considered to be predominantly EqCD4+ cells) tha n controls. Hay and straw challenge increased the ratio of BALF EqCD5CD8- 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 all ergen challenges.