Phenotypic and functional analysis of mucosal T cells isolated from tissue explants of rat upper respiratory tract

It has been hypothesised that T cells play a central role in the pathogenesis of asthma which is characterised by chronic inflammation of the airways. In order to further study the T cells identified in situ in the airways we have developed, in the rat, a novel method for the extraction of T cells directly from the airway mucosa. The T cells actively migrate from explant tissue under the influence of exogenous IL-2 yielding sufficient cells for phenotypic and functional analysis. The T cells obtained represent a random selection of cells present at the start of culture as determined by dot blot analysis of the T cell receptor. The majority of cells were CD8+ and did not express the alpha/beta T cell receptor. In addition, the cloning efficiency of the explant T cells was extremely low (1:28) compared to that of splenic T cells (1:2) in agreement with our earlier studies on peripheral lung T cells which also demonstrated a reduced proliferative capacity. This data suggests a generalised 'immunosuppressive' milieu throughout the respiratory tract.