HLA-B and graft versus host disease: Importantly, we found that HLA-B*08:01-restricted T cells isolated from donors that were homozygous for HLA-B*08:01 or heterozygous for HLA-B*08:01 and a specific HLA-B allele (e.g., HLA-B*13:02) showed abundant allo-HLA cross-reactivity in vitro and are therefore likely to cause graft rejection or GVHD in vivo.