Prevention of renal allograft rejection in primates by blocking the B7/CD28 pathway

Induction of hyporesponsiveness to fully allogeneic cardiac grafts by intratracheal delivery of alloantigen

BACKGROUND

Soluble protein delivered through the mucosal surface can induce immunological unresponsiveness. The purpose of this study was to determine if prior exposure to alloantigen via the trachea could modulate the immune response to subsequent cardiac allografts.

METHODS

Hearts from C57BL/10(H2b) mice were transplanted into CBA(H2k) recipients. Recipient mice were given donor 1x10(7) splenocytes into the trachea with or without antibody specific for mouse CD80 (1G10) and/or CD86 (GL1) (100 microg each) 7 days before transplantation.

RESULTS

All grafts survived in recipients treated with intratracheal delivery of alloantigen for over 35 days (mean survival time [MST], 56 days), whereas naive control mice and mice treated with syngeneic antigen rejected grafts acutely (MST, 8 and 7 days, respectively). Interestingly, when 1G10, GL1, or both of them were combined with the protocol, the majority of grafts were rejected within 21 days after grafting (MST, 7, 15, and 17 days, respectively).

CONCLUSION

Intratracheal delivery of alloantigen induced significantly prolonged survival of fully mismatched cardiac allografts and the effect was abrogated by the blockade CD80 and/or CD86 pathway.

[The regeneration of therapeutic muds from Varzi-Iatchi health resort]

Organ grafts transduced with gene-encoding immunosuppressive molecules are a less toxic approach to preventing graft rejection. Adenovirus vectors have been widely tested with unsatisfactory results, while adeno-associated virus (AAV) is smaller and elicits a low host humoral response. We constructed an AAV vector containing the mouse CTLA4Ig gene. B10 (H2(b)) cardiac grafts were transduced with AAV-CTLA4Ig by coronary infusion. AAV-LacZ vectors were used as reporters and controls, and the expression of beta-gal was determined by X-gal staining. Thirty percent to 40% of myocytes displayed strongly positive X-gal staining after infusion with AAV-LacZ. Additional infusion with vascular dilator reagents did not improve the transduction rate. Survival of B10 heart allografts transduced with AAV-CTLA4-Ig was significantly prolonged in C3H (H2(k)) recipients. These data demonstrate that AAV vectors can efficiently be transduced into the mouse myocardium by coronary infusion. Graft transduction with AAV-CTLA4Ig may be a novel approach to preventing allograft rejection.