PROBLEMS AND POSSIBLE SOLUTIONS IN FINDING AN UNRELATED BONE-MARROW DONOR - RESULTS OF CONSECUTIVE SEARCHES FOR 240 DUTCH PATIENTS

To evaluate the efficiency of our protocol for finding an HLA matched unrelated bone marrow donor, search results obtained between 1990 and 1995 for 240 Dutch patients were analyzed. The percentage of patients for whom, according to information given by the registries, a fully sp lit-HLA antigen matched donor is available, increased from 24% in 1990 to over 70% in 1995. As a result the percentage of patients transplan ted rose from about 24% in 1990-1991 to 44% in 1994-1995. The median t ime between the start of the search and transplantation was about 6 mo nths. The systematic use of Bone Marrow Donors Worldwide (BMDW) which comprises the HLA groups of all volunteer bone marrow donors in Europe , Israel, South Africa, North America, Canada, India, Australia and Ne w Zealand has been essential in this context. While searching for a su itable donor several problems were encountered such as unavailability of donors (12%) and discordant typing results (8%; range <1% to >25%). Thus it is advisable to select several donors for a patient. For 86% of patients with at least one HLA identical donor on the serological l evel for HLA-A,-B,-DR,-DQ, an HLA-DRB1/3/4/5, and -DQB1. identical don or could be identified. As expected, patients with two frequent haplot ypes in strong linkage disequilibrium had the best chance of obtaining an HLA matched donor. Unexpectedly, patients with only one such haplo type had an almost similar chance. It could be calculated that HLA-DR typing of HLA-A,-B identical donors was rarely cost-effective after 19 92. Only 12 of the 75 transplanted patients (16%) typeable at DNA leve l for class II, turned out to be completely matched for HLA-A,-B,-C,-D RB1/3/4/5,-DQB1,-DPB1 and had a negative MLC test. In the group of pat ients transplanted with a fully matched donor and for whom a CTLp test was performed, only 7% (4/54) of the tests were negative. Search resu lts for patients of non-European origin were dismal, with only four of 26 patients referred being transplanted. In summary, of the 240 patie nts for whom the Europdonor office searched for a donor, about one-thi rd were transplanted, one-third had a potential donor but did not reac h transplantation, while for the remaining one-third of patients no su itable donor could be found.