Phenotypic analysis of lymphocytes obtained by bronchoalveolar lavage of normal sheep

Lungs were excised from apparently healthy sheep at slaughter and lymphocytes obtained by bronchoalveolar lavage were separated by buoyant density and characterised phenotypically. In most animals T-lymphocytes (CD5+ cells) accounted for almost the entire population, with B-lymphocytes (sIg+ cells) generally accounting for less than 10%. In the main, CD4+ T cells exceeded CD8+ T cells by at least a factor of three and CD4-/CD8- (gamma delta) T cells represented around 6% of the population. Proportions of subtypes of lymphocytes obtained by bronchoalveolar lavage differed from those in peripheral blood. The normal range of lymphocyte phenotypes in the ovine lung established in this study will be of value in subsequent work on animals with defined respiratory disease.