Experiment was designed to compare cellular profile of bronchoalveolar lavage following induced bacterial infection, acute rejection and acute rejection plus bacterial infection after lung allotranplantation.

After single lung allotransplantation, dogs were immunosuppressed with standard triple therapy and divided into 4 groups. Group I(n=4) was maintained on immunosuppression as controls. In group II(n= 6), infection was induced by bronchoscopic inoculation of E. coli at postoperative day 5. In group III(n=6), triple therapy was discontinued to induce acute rejection from postoperative day 5. In group IV(n= 8), triple therapy was discontinued and bacterial infection was induced by bronchoscopic inoculation of E coli at postoperative day 5.

At postoperative day 9, bronchoalveolar lavage was obtained in the native and transplanted lung resprctively through bronchoscopy. Total cell count and differential cell count of bronchoalveolar lavage were compared in four groups.

In the native lung, there was no significant difffrence in total cell count and differential cell count in four groups. In the transplanted lung, total cell count of group II(Infection) was increased, compared to group III(Rejection) (p <0.05). In the transplanted lung, differential neutrophil count of group II(Infection) and group III(Rejection) were increased, compared to group I(Immunosuppression) (p <0.05). In the transplanted lung, differential macrophage count of group II(Infection), III(Rejection) and IV(Rejecion plus Infection) were decreased, compared to group I(Immunosuppuression) (p<0.05).

Cellular profile of bronchoalveolar lavage reflected the pathological process ofinfection or acute rejection following lung allotransplantation in the transplanted lung. But conventional total and differential cell counts had limitation to differentiate either process.