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(H2(b)) mice were transplanted into CBA(H2(k)) 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 mug 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.