Phenotypic analysis of bronchoalveolar lavage fluid lymphocytes in horses with chronic pulmonary disease

A panel of specific antibodies against CD3, CD4, CD5, CD8, MHC I and II was used in single and two colour flow cytometry tu define T cell subpopulatio ns in bronchoalvelar lavage fluid of horses affected with chronic obstructi ve pulmonary disease and of healthy controls. Recording to the results of t he clinical examination including bronchoscopy and cytology of the tracheal aspirate the horses were divided into four groups (healthy, subclinically to mildly affected; moderately affected, and severely affected). All groups of horses had a similar percentage of CD3+ cells in the BALF. Co mpared to controls, severely affected horses had a significantly increased number of CD4+ cells in the BALF, but a similar percentage of CD4+ cells wh ereas mildly and moderately affected horses had a decreased percentage. The percentage and number of CD8+ cells and the percentage of CD8+/MHCII+ cell s in the BALF was found to be higher than normal and varied according to th e disease state. This novel finding raises the possibility that not only th e CD4+ cells but also the CD8+ cells are involved in the pathogenesis of CO PD. The percentage and the number of CD8+ cells in BALF might be of diagnos tic value to detect subclinical to mild cases of COPD.