FACS profile of PBMC obtained from a recipient 314 days after bone marrow and kidney transplantation. (A) Isotype-matched irrelevant antibody used as control. (B) Monoclonal antibody specific for HLA class I (anti-B7, IgG1; HB59, ATCC, Rockville, MD) was used to identify circulating donor cells. PGE, percentage gated events.