Cd4-targeted therapy with a nondepleting (RIB-52 monoclonal antibody (mAb) abrogates
accelerated rejection and produces permanent acceptance of cardiac allografts in
presensitized rat recipients, in association with diminished host circulating allo-Ab
responses, induction of peripheral allospecific T cell unresponsiveness in vitro and in vivo,
and profound depression of both Th1-and Th2-type cytokines at the graft site. This striking
therapeutic effect is accompanied by features characteristic for infectious tolerance, based …

The infectious tolerance, as originally described by Dr. H. Waldmann's group, was induced
and perpetuated in adult thymectomized (ATX) mouse recipients of skin allografts (Tx). We
have recently shown, however, that cardinal features of such a classic peripheral form of
tolerance may be applied to euthymic rats. Hence:(i) treatment of sensitized rats with RIB-
5/2, a CD4 nondepleting mAb, abrogated accelerated (< 36 h) rejection, and produced
indefinite cardiac Tx survival;(ii) tolerant cells in mAb-treated hosts could disable naive or …