Proliferative responses of T-cell lines at 1 year after allo-BMT. ³H-thymidine incorporation assays of TT-specific T-cell lines after stimulation with PHA, TT, or culture medium as negative control. Depicted on the y-axis is the SI: SI =³H thymidine incorporation of T-cell lines + APC+ TT/³H thymidine incorporation of T-cell lines + APC only. Shown are the results of 2 recipients of transplantation groups I (UPN 272 and 279) and III (UPN 275 and 285) and of 1 recipient of group II (UPN 301) and of their corresponding BM donors.