ANALYSIS OF CELLS OBTAINED BY BRONCHIAL LAVAGE OF INFANTS WITH RESPIRATORY SYNCYTIAL VIRUS-INFECTION

To study the cellular infiltrate that occurs within the airways of inf ants with respiratory syncytial virus bronchiolitis, samples of airway s secretions were obtained by bronchial lavage from the lower respirat ory tract of infants ventilated for this condition and from the upper airway of non-intubated infants with this disorder using nasopharyngea l aspirates. Cytospin samples were prepared so that differential cell counts could be performed on the cells obtained and alkaline phosphata se-antialkaline phosphatase immunocytochemical analysis of lymphocyte subsets was carried out using a panel of monoclonal antibodies, which included anti-CD3, anti-CD4, anti-CD8, anti-CD19, and anti-TcR gamma d elta. Results from the lower and upper airways were similar. Large num bers of inflammatory cells were obtained, of which neutrophils account ed for a median of 93% in the upper airway and 76% in the lower airway . The numbers of CD8 positive cells detected were small and consistent ly less than CD4 positive cells, median CD4:CD8 ratios being 22.5:1 an d 15:1 for the lower and upper airways. CD19 positive cells were rarel y observed and no gamma delta positive lymphocytes were detected. Thes e results indicate that neutrophils probably play a major part in caus ing symptoms in these infants. They do not support the concept that ex cessive lymphocyte mediated cytotoxic activity is principally responsi ble for the pathology in respiratory syncytial virus bronchiolitis.