Lung allograft rejection in the rat. V. Inhaled stimuli aggravate the rejection response

Responses to inhaled stimuli in lung allografts might intensify the rejection response against the grafts. Therefore, we investigated the rejection of lung allografts in rats exposed to various degrees of stimuli via the airways. A group of these rats was selectively decontaminated to eliminate infection of the graft. Stimuli provided were intrabronchially injected purified protein derivative in sensitized rats and dust inhaled from sawdust used as bedding in the cages. Both intrabronchially injected purified protein derivative and stimuli inhaled from sawdust were found to aggravate lung allograft rejection, thus shortening mean graft survival from 32 to 11 days. Selective decontamination did prolong lung graft survival (p less than 0.05) because it lowered the overall immune reactivity of the recipient rats. For clinical lung transplantation, these observations suggest that patients should be selectively decontaminated and protected against inhalation of exogenous stimuli during a rejection episode.