Immunological reconstitution after cord blood transplantation for an adult patient

We transplanted 4.1x10(7) unrelated umbilical cord blood cells into a 27-year-old patient suffering from transformed acute myelocytic leukemia. The thawing method was the same as described by Rubinstein et al (Proc. Natl. Acad. Sci. USA 1995; 92: 10119-10122). ANC reached over 500x10(9)/l on day 19, and the patient was free from RBC and platelet transfusion on days 26 and 38, respectively. Cytogenetic and molecular analysis after transplant revealed complete chimerism. The CD3+CD4+ lymphocyte count became greater than 100x10(9)/l at 5 weeks after transplantation. The CD3+CD8+ count became greater than 500x10(9)/l at 7 weeks and thereafter progressively increased in spite of administration of CYA. This immunological reconstitution pattern after umbilical cord blood transplantation was different from that after bone marrow transplantation, and resistance of CD3+CD8+ lymphocytes to CYA was the distinguishing characteristic. The rapid hematological recovery and immunological reconstitution may be attributed to the high dose of transfused nucleated cells and umbilical cord blood transplantation may become a promising method for treatment for such cases.