Precursor frequency of donor-specific lymphocytes recovered from canine lung transplants

Dogs receiving left unilateral allo- or auto-grafts were treated with Cyclosporin A (Cy A) for 4 days. Thereafter allografted transplant recipients showed pulmonary pathology consistent with rejection. Blood and bronchoalveolar lavage (BAL)-derived lymphocytes were isolated from the recipient animals before and at various times after operation and the frequency of allospecific precursor cytolytic lymphocytes (pCTL) determined by limiting dilution analysis (LDA). Samples from the autografted control animal did not show any post-operative frequency changes; however, both blood and BAL-derived lymphocytes from allografted recipients showed a significant post-operative increase in the proportion of donor-specific pCTL. This increase was consistently greater in samples from the transplanted than the autochthonous lung. The frequency of pCTL determined using targets from an unrelated dog showed no post-operative increase. It is likely that the increase in frequency of donor-specific pCTL recorded during graft-rejection is a specific consequence of an interaction between the graft and recipient's immune system.