Lethally irradiated BALB/c recipients were transplanted with spleen cells (75×106) and BM cells (2.5 ×106) from DBA/2 donors and injected i.v. with either rat IgG or anti-CD20 mAb (40 mg/Kg) the following day. Control recipients were given BM cells alone. Recipients were monitored for clinical GVHD, including hair loss, proteinuria and survival († indicates death of all recipients in a group). (A–C) Percentage of recipients without (A) proteinuria, (B) clinical cutaneous GVHD score, and (C) percentage of survival. Each group contained 20 recipients combined from five replicate experiments. (D) Twenty-five and one hundred days after HCT, recipients thymuses were measured for percentage of CD4+CD8+ thymocytes and a representative pattern is shown of 4 replicate experiments.