Case report: A transplant candidate with unexpected serum reactivity against the 45KE eplet on HLA-B alleles

This case report describes the serum antibody specificity against the 45KE eplet which had not been yet shown to be antibody-verified. This antibody was produced by a 41-year-old European male with Berger's disease. His serum had HLA class I antibody reactivity as determined in IgG binding assays with single allele panels (OneLambda, ThermoFisher, Lot 8 and Lot 9). The HLAMatchmaker analysis revealed reproducible serum reactivity only with alleles carrying the 45KE eplet. The cause of this 45KE-specific immunization is unknown because this male patient had never been transfused nor received a previous transplant, Moreover, his mother's HLA type did not have any 45KE-carrying allele. This finding might be related to observations reported in the literature about the appearance of HLA-reactive antibodies following influenza vaccination but this possibility could not be investigated.