TAP1 AND TAP2 POLYMORPHISM IN HLA-B27-POSITIVE SUBPOPULATIONS - NO ALLELIC DIFFERENCES IN ANKYLOSING-SPONDYLITIS AND REACTIVE ARTHRITIS

The polymorphic TAP1 and TAP2 genes encode subunits of the transporter that delivers peptides to the HLA class I molecules. Because the poly morphism of the TAP genes has been shown to affect peptide transport, it has been suggested that TBP genes are potential regulators of the i mmune response. We studied TAP1 and TAP:! polymorphism in two multifac torial HLA-B27-associated diseases, ankylosing spondylitis (N = 30) an d reactive arthritis (N = 30), in order to establish whether TAP genes are involved in the different pathogenesis of these diseases. Healthy HLA-B27-positive individuals (N = 55) were chosen as the primary cont rols and 93 individuals represented the random Finnish population as s econdary controls. We found differences between the random and HLA-B27 -positive populations, thus suggesting that certain TAP alleles are pr evalent in HLA-B27 haplotypes. No differences were found between the A S and ReA groups nor between either of them and the healthy HLA-B27-po sitive controls. Thus it seems unlikely that TAP polymorphism, at the level studied, has a dominant role in the pathogenesis of these diseas es. However, a family study is needed in order to determine whether th e same TAP complexes are carried by the same haplotypes in these disea ses.