NEW STRATEGIES FOR SELECTION OF UNRELATED BONE-MARROW DONORS

An important problem in the selection of unrelated donors for bone marrow transplantation (UD-BMT), is HLA matching, between selected donor and recipient. Serological screening, mixed lymphocyte culture (MLC), and sequence specific olygonucleotide genotyping (PCR-SSO) are the methods commonly used for typing of HLA-genes. These ways to select donor candidates are time-expensive. We set up new applications of the ''fingerprinting-PCR'' technique, to analyse the polymorphic second exon of DRB, DQB, DQA, DPB of HLA Class II and second exon A, B, C HLA-class I genes, and to search for identity between patient and serologically selected unrelated donors. In an assessment of the technique, 50 normal samples, and 4 unrelated HLA-A and HLA-B serological matched patient-donor pairs were analysed for HLA polymorphic regions. In 3 of the 4 cases (UD-BMT) at least HLA-DRB mismatched different donor-transplanted patterns were identified. In all cases PCR-SSO analysis was performed as control. Based on our data, we suggest that identification of UD for allogeneic BMT should follow these steps: 1) serological HLA-Class I and II genes screening; 2) HLA-Class II DRB gene PCR fingerprinting; 3) confirmation by SSO analysis in case of fingerprinting identity. 4) HLA-Class II DQA, DQB, DPB PCR fingerprinting. Moreover, confirmation by PCR fingerprinting or protein isoelectrofocusing of HLA-Class I identity is recommended. This ''strategy'' may contribute to rapid and specific selection of unrelated marrow donors.