shaped to fit the graft bed positioned and covered with baseline gauze a bandage was then wrapped circumferentially around the chest to protect the graft the grafts were inspected daily beginnning on day 6 or 7 and considered rejected when greater than 50 of the epithelium was non viable the monoclonal antibody employed was antibody m7 20 which is described in gaulton et al 1985 clin immunol and immunopath m7 20 as a monoclonal rat anti mouse k u ig antibody specific for the il 2 receptor m7 20 was purified from the culture supernatants of cells grown in serum free media hanna labs berkeley calif supernatants were precipitated with 40 50 saturated ammonium sulfate dialyzed passed over deae affi gel blue bio rad richmond va in 20 mm nacl and the eluate fractionated on sephadex g 200 pharmacia piscataway n j run in 20 mm tris ph 7 2 250 mm nacl 0 5 n butanol antibody purity was assessed by sds page gel electrophoresis there was also employed a control monoclonal antibody ra3 2c2 not specific for the il 2 receptor the hybridoma producing ra3 2c2 which binds to pre s cells and to some mature b cells was obtained from the american type culture collection rockville md and the antibody purified by the procedure described above for m7 20 both antibodies were diluted to a final concentration of 25 u03bcg ml in phosphate buffered saline treated recipients of heart or skin allografts received 0 2 ml 5 u03bcg by intraperitoneal.