An HLA-B7-specific antibody in an HLA-B*07 positive patient explained by a nonexpressed allele (HLA-B*07:181N).

Antibody identification by a bead array assay in a kidney patient revealed several HLA-specific antibodies including one directed against the HLA-B7 antigen. Low-resolution typing of the patient indicated the presence of an HLA-B*07 allele. To rule out an HLA-specific autoantibody the HLA-typing of the patient was further refined by nucleotide sequencing on a next-generation sequencing platform and eventually showed an HLA-B*39:01:01:03 and HLA-B*07:181N genotype. Thereby the allospecific nature of the antibody was proven. The HLA-B7-specific antibody could be explained by an immunization during the first kidney-transplantation in 1996 with an HLA-B*07 positive donor. When assessing the plausibility of antibodies, the presence of nonexpressed alleles should be taken into consideration.