STABLE MIXED CHIMERISM WITHOUT RELAPSE AFTER RELATED ALLOGENEIC UMBILICAL-CORD BLOOD TRANSPLANTATION IN A CHILD WITH SEVERE APLASTIC-ANEMIA

Umbilical cord blood (UCB) cells from HLA-matched donors are used as a n alternative to bone marrow for allogeneic transplantation and report s of successful UCB transplantation in patients with severe aplastic a nemia (SAA) are scarce. SAA was discovered in a 4-year-old girl in Feb ruary 1990. Transfusion support started in August 1990 and standard tr eatments were unsuccessful. The birth of an HLA-compatible brother in October 1993 permitted the cryopreservation of UCB, In December 1994 U CB transplantation was decided upon. No toxicity occurred. G-CSF was s tarted at day 28, WBC and PMN reached 0.5 x 10(9)/1 at days 33 and 37, RBC and platelet transfusion independence were reached at days 50 and 52, Mixed chimerism was demonstrated in blood cells at 1.5, 4 and 6 m onths after UCBT by molecular biology (VNTR), FISH studies yielded sim ilar results at 15 and 18 months, Twenty months after UCBT, molecular biology showed full donor chimerism, Clinical follow-up (last follow-u p: 32 months post transplant) is unremarkable, We suggest that CY and ATG may be a suitable regimen for related HLA-compatible UCBT in patie nts with SAA, Residual recipient cells can disappear even very late af ter UCBT, permitting the establishment of complete donor chimerism.