Reduced antibody responses after immunization in rat lung transplants.

Pulmonary infections occur so frequently in recipients of lung transplants as well as of combined heart and lung transplants that it has been suggested that the function of the defense system in lung transplants is impaired. Therefore, we investigated in rats whether antibody responses against intrapulmonary antigens were impaired at various time points after transplantation. Antibody responses were induced in lungs of four experimental groups. Group 1: normal lungs (LEW); Group 2: hilar-stripped (sham-operated) lungs (LEW); Group 3: syngeneic lung transplants (LEW-to-LEW); Group 4: allogeneic lung transplants (BN-to-LEW). The operations were performed on the left lungs. All rats (including those with normal lungs) were treated with cyclosporine on Days 2 and 3 after operation, which treatment is adequate to induce permanent graft acceptance of the allografts. Rats were immunized 7, 10, 14, 21, and 28 days and at 6 months after operation with sheep red blood cells, injected selectively into the bronchus of the left lung. The resulting serum antibody titers were detected with a hemolysis assay. After immunization on Day 7, no antibody responses could be detected in all hilar-stripped and transplanted rats, whereas responses were normal in two allografted rats immunized in the nontransplanted right lung. After immunization on Day 14, responses had returned to normal in hilar-stripped rats, whereas they were still impaired in the transplanted rats. After immunization on Day 28, responses were almost normal in all rats and remained so until 6 months after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)