Markers for eosinophils and T-lymphocytes as predictors of late asthmatic response

Bronchial allergen challenge was performed on 12 allergic asthmatics during a stable phase of their disease. After resolution of the immediate bronchial response, fractional lung lavage was performed twice, two and 24 h post-challenge. The recovery of eosinophils, eosinophil cationic protein (ECP), eosinophil chemotactic activity (ECA) and immunohistochemical staining of the phenotypically distinct population stainable by the monoclonal antibody CD45RO, agreed to indicate T-memory cells, were assessed in the two lavages. Serial measurements of lung function, and serum concentration of ECP were also done. We found that although the recoveries in bronchial washes of eosinophil cells and ECP tended to increase during the trial, none of these variables predicted the emergence of late phase bronchial response (LPR). Instead, the proportion in the 2-h lavages, of memory-cells or ECA predicted the LPR. These two variables were inversely correlated to each other in the first lavage, suggesting the T-cells to be potential major sources of ECA. The fact that T-cells and ECA, but not markers for eosinophil activation in lavage, predicted the LPR, may suggest T-cell activation to precede the activation of the eosinophils within the lung after a bronchial allergen challenge. There was a close correlation between LPR and serum concentration of ECP obtained at the end of the trial, 24 h post-challenge, suggesting either a delayed or a continuous activation of circulating eosinophils after bronchial allergen challenge.