A NOVEL COMMON KELL ANTIGEN, TOU, AND ITS SPATIAL RELATIONSHIP TO OTHER KELL ANTIGENS

A 47-year-old native American (TOU) was admitted to hospital for hip surgery. His serum agglutinated all red blood cells (RBCs) tested except Ko and DTT treated RBCs and was weakly reactive with RBCs known to have a weak expression of Kell antigens, namely Kmod, McLeod, Kp(a+b-) (KEL:3,-4) and K:-13 (KEL:-13) phenotypes. RBCs from three siblings, a son and a daughter were incompatible with TOU's antibody. TOU's RBCs had the common Kell phenotype: K-k+Kp(a-b+c-) Ku+ Js(a-b+) Ul(a-) K:11, -17 K:14,-24 K:12,13,18,19, 22,-23 (KEL:-1,2,-3,4,5,-6,7,-10,11,12,13,14,-17,18,19,-21,22,-23,-24). Since TOU's RBCs were not agglutinated by an unidentified Kell-related antibody (IAN), tests were performed to show that TOU and IAN were mutually compatible. IAN is a Latino female hospitalised for a hysterectomy. The TOU antigen was shown to be located on the Kell glycoprotein by a monoclonal antibody immobilisation of erythrocyte antigen (MAIEA) assay. The unique pattern of reactivity obtained with TOU and IAN antibodies using this assay indicated the TOU epitope to be in an area remote from other Kell antigens, namely K, k, Kp(a), Kp(b), Kp(c), Ku, Js(a), Js(b), Ul(a), K11, K12, K13, K14, Wk(a), K18, K19, K22 and K24 (KEL1, KEL2, KEL3, KEL4, KEL5, KEL6, KEL7, KEL11, KEL12, KEL13, KEL14, KEL17, KEL18, KEL19, KEL21, KEL22 and KEL24) but close to the low-incidence antigen K23 (KEL23). Investigation of antibodies to previously identified antigens on the Kell glycoprotein by MAIEA using the mouse monoclonal antibodies BRIC18, BRIC68, BRIC107 and BRIC203 has identified six patterns of reactivity and has provided evidence for Kp(c) being located in the same region as Kp(a) and Kp(b).