Immunization of recipient with donor immobilized non-dividing splenocytes significantly prolongs allogeneic heart survival

Background: On the contact of recipient with the donor, transplantation antigens evoke humoral and cellular rejection reaction. Blood transfusions, pregnancy and previous grafts may cross-reactively immunize recipient against donor antigens. In all the mentioned cases donor antigens are mainly supplied by "passenger cells". These cells colonize recipient lymphoid tissues and produce progenies. This enhances immune response and subsequently rejection. The question arises whether metabolically immobilized non-dividing (mummified) donor cells administered to recipient prior to transplantation may mitigate rejection reaction, presumably by evoking formation of enhancing antibodies. Immobilisation can be achieved by treating the donor cells with pulverized NaCl. These cells retain their molecular structure but do not divide. Aim: to immunise recipient with donor NaCl-treated splenocytes prior to heart transplantation.
Material/Methods: BN rat spleen fragments were placed in pulverized NaCl and 7 d later implanted intraperitoneally into LEW rat on d 0 and 7. Seven days later heart TX from BN was performed. Non-immunized rats served as controls. No immunosuppression was given.
Results: the immunised LEW did not reject BN heart until d 20 (20±2),
whereas control rats rejected the graft within 6±1 days (p<0.001). Histology
showed that rejected hearts from immunised recipients' revealed hypertrophied muscle with few infiltrates, in contrast to controls with dense infiltrates and necrotic areas. Deposition of IgG in graft vessels could be seen on immunohistochemical pictures.
Conclusions: Immunisation of recipient with mummified splenocytes retaining their molecular structure may be responsible for prolongation of allogeneic heart survival.

Keywords: Heart Transplantation, Immunosuppression, Tissue Transplantation