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

Background. Soluble protein delivered through the mucosal surface can induc e immunological unresponsiveness, The purpose of this study was to determin e if prior exposure to alloantigen via the trachea could modulate the immun e 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 t rachea 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 deliv ery of alloantigen for over 35 days (mean survival time [MST], 56 days), wh ereas naive control mice and mice treated with syngeneic antigen rejected g rafts acutely (MST, 8 and 7 days, respectively). Interestingly, when 1G10, GL1, or both of them were combined with the protocol, the majority of graft s were rejected within 21 days after grafting (MST, 7, 15, and 17 days, res pectively). Conclusion. Intratracheal delivery of alloantigen induced significantly pro longed survival of fully mismatched cardiac allografts and the effect was a brogated by the blockade CD80 and/or CD86 pathway.