Donor-specific cytotoxic lymphocyte activity from bronchoalveolar lavage during acute canine lung allograft rejection

We investigated the relationship between acute lung rejection and donor-specific cytotoxic activity (DSCA) in recipient's lymphocytes obtained from bronchoalveolar lavage (BAL).

A total of 26 mongrel dogs underwent left lung allotransplantation. Dogs received either no immunosuppressive treatment (group I), cyclosporine (group II), or cyclosporine and methylprednisolone for evidence of acute rejection (group III). DSCA was measured by a 51Cr release assay, using lymphocytes from BAL samples as effector cells and 51Cr-labeled donor skin fibroblasts as target cells. The pathologic findings of the transplanted lungs were classified according to the working formulation for classification and grading of pulmonary rejection. In addition, the degree of cellular infiltration in the perivascular, peribronchial, interstitial, and intraalveolar areas was determined based on an infiltration score.

DSCA in BAL samples was elevated during mild, moderate and severe acute rejection. The accuracy of the diagnosis of mild or moderate rejection was 92.3% at effector:target (E:T) ratios of 100:1 and 50:1. The DSCA in the BAL fluid and the total infiltration score were correlated closely with correlation coefficients of 0.859 and 0.828 at E:T ratios of 100:1 in group I and group II dogs, respectively. Lung aeration improved and DSCA decreased with methylprednisolone therapy in three of four dogs with grade 2 rejection.

There is a direct relationship between the DSCA in BAL fluid and the degree of tissue damage caused by acute rejection. The DSCA can be detected by a 51Cr release assay which may hold promise for future clinical applications.