The recently proved importance of molecular HLA-Cw compatibility for the result of bone transplantation among not related persons (UBMT) brought up the question of probability of compatibility of non-related donors with the patient in this locus as so far the main criterion of donor selection compatibility in HLA-A,B,DR loci. In a group of 59 candidates of UBMT and their 76 potential not related donors who were otherwise molecularly HLA-A,B,DR,DQ compatible we tried to analyze the frequency and type of HLA-Cw incompatibility. A total of 24 donors (32 % of all donors) were incompatible in HLA-Cw with 18 potential recipients (31 % of all recipients). The general probability of HLA-Cw compatibility in all potential pairs of non-related donor-recipients was 0.84. From a total of 118 possible haplotypes of recipients, 30 (25.4 %) were those most frequent in our population, i.e. A1B8DR3 and A2B7DR15, whereby their ratio in all HLA-Cw discrepancies was only 8 %. Conversely the remaining haplotypes (74.6 % of haplotype recipients) accounted for more than 90 % of the mentioned incompatibilities. The general probability of HLA-Cw compatibility for A1B8DR3 and/or A2B7DR15 was 0.95 but for the remainder only 0.81. The presented data provide evidence of the importance of accurate assessment of molecular HLA-Cw compatibility even in common haplotypes and in tase of compatibility in the other HLA loci.

        Key words: HLA compatibility, Cw locus, bone marrow transplantation