Poor immune reconstitution after four or five major HLA antigens mismatched T cell-depleted allogeneic and autologous stem cell transplantation

Two adults with primary liver cancer underwent liver transplantation from 5 /6 and 4/6 major HLA-antigen mismatched unrelated donors. They were then co nditioned with 4 x 2 Gy of total lymphoid irradiation, 120 mg/kg cyclophosp hamide, 7.5 Gy total body irradiation and anti-T cell antibodies. Thereafte r, the patients received T cell-depleted autologous: unrelated mismatched b one marrow in a proportion of 0.5:3.0 and 0.35:1.1 x 10(6) CD34(+) cells/kg , respectively. After allogeneic stem cell transplantation (ASCT), both bec ame mixed chimeras, as determined with polymerase chain reaction amplificat ion of variable number tandem repeats from DNA obtained from CD3(+), CD19() and CD45(+) magnetic bead-separated cells. Due to a reduction in donor T cells, the first patient was given 10(5) donor T cells/kg and became a comp lete donor chimera within 3 months. The second patient rejected all donor c ells within 1 month after ASCT. Leucocytes normalized in both patients with in 1 month. CD8(+) cells normalized after 4 and 2 months in the two patient s, respectively. However, CD4(+), CD56(+) and CD19(+) cells remained low, e xcept for a transient increase in patient 2. Lymphocyte responses to mitoge ns were negative in patient 1 from 1 to 5 months after ASCT. This patient a lso showed an oligoclonal pattern of the B cell repertoire, performed by CD R3 spectratyping. Epstein-Barr virus DNA in lymphocytes increased by 4-5 lo g in both patients. Prior to ASCT, recipients and donors were mutually reac tive in mixed lymphocyte cultures (MLC). In the first patient, who became a complete donor chimera, the chimera cells showed no response to recipient or donor, but a positive response to third party. In the other patient, rec ipient cells reacted vigorously against donor lymphocytes at the time of re jection. Both patients suffered from overwhelming bacterial, fungal and vir al infections, and died of pneumonia 5 and 3 months after ASCT, respectivel y. To conclude, with a major HLA-mismatch barrier, stable mixed chimerism s eems difficult to achieve. The first patient became a full donor chimera an d the second one rejected the graft. Both suffered from immune incompetence .