Conditioning therapy and GVHD prophylaxis in 72 recipients of PMRD allo-BMT. In an effort to improve engraftment, the total dose of TBI was increased from 1,332 cGy (administered to the first 45 patients) to 1,500 cGy (administered to the subsequent 27 patients). Cyclosporin and prednisone were gradually tapered and discontinued in patients free of acute and/or chronic GVHD. Abbreviations: TBI , total body irradiation administered twice daily via AP/PA fields with ∼50% pulmonary transmission with lung shielding and electron beam boosting of chest wall, and testicles (ALL, biphenotypic) using an instantaneous dose rate of 13 to 22 cGy/min and interfraction interval of ∼8 hours; VP-16 ✶, etoposide administered once (omitted for nonmalignant disease); Ara-C ⬇, cytosine arabinoside administered twice daily × 6 doses; CTX ✳, cyclophosphamide administered daily × 2 doses; H-D MPD ⇩, high-dose methylprednisolone administered every 12 hours × 4 doses; T₁₀B₉ + C BMT ▴, marrow graft T-cell depleted with T₁₀B₉ and complement, L-D CYS ▹, low-dose cyclosporin started day −1 at 3 mg/kg constant infusion and maintained at levels between 100 to 200 as measured by monoclonal antibody technique, switched to orally after day +21 and weaned gradually through the first year post-BMT; M-D MPD ⇩, moderate-dose methylprednisolone administered before ATG; ATG ♦, antithymocyte globulin administered daily × 12 doses on day +5 to +16; ⇩ MPD/Pred; steroid dose tapered 10% weekly and switched to prednisone orally after day +21; ❁BMT➭, days before and after BMT; →, expanded time period.