The amino acid sequence alignment of the alleles of each SLA locus is shown. For the haplotypes with a specific set of amino acids (Y102, L103, L109; the YLL set), in which each allele reacted with X2F6, the number of YLL sets determined the level of reactivity. The MFI for X2F6 reactivity was highest in the Hp-10.0 PBMCs that possessed three YLL sets in the SLA-1, SLA-2 and SLA-3 loci.