K12 Is Located on the Kell Blood Group Protein in Proximity to K/k and Js^a/Js^b

Abstract

K12 is a high-prevalence antigen, with no known antithetical partner, that is associated with the Kell blood group system. We report studies on the 5th propositus (MS) with the K:-12 phenotype and the second case to show that the K12 is inherited. The anti-K12 in his serum did not destroy antigen-positive incompatible red cells transfused on at least 3 occasions over 6 years. Red cell membranes from MS possessed the Kell protein that was indistinguishable from control membranes. K12 antigen was shown by immunoprécipitation to be on a protein with an apparent molecular mass of 93,000 and by monoclonal antibody immobilization of erythrocyte antigens (MAIEA) assay to be on the Kell protein in proximity to K/k and Js^a/Js^b antigens. These data remove the K:-12 phenotype from its current Kell-related (or para Kell) status and elevates the K12 antigen to a bona fide member of the Kell blood group system.

Molecular Basis of Kell Blood Group Phenotypes

“…The MAIEA assay is an immunologic procedure that groups antigens which are spatially in proximity [45]. This technique has been utilized to group several Kell-related antigens [37,[45][46][47][48][49]. Some of the Kell antigens, as determined by MAIEA, appear to be close together but, as determined by gene sequencing, are linearly far apart.…”

The monoclonal antibody‐specific immobilization of erythrocyte antigens assay (MAIEA) in the investigation of human red‐cell antigens and their associated membrane proteins

“…From the information obtained from MAIEA performed with these and other monoclonal antibodies, together with human alloantibodies to Kellsystem antibodies, we have been able to suggest positions of the Kell-system antigens relative to each other, based on the assumption that a negative result represents mutual blocking between the antibodies. Figure 4 represents, diagrammatically, our results Petty et al, 1994;Jongerius et al, 1996;and unpublished observations) together with those of others Reid et al, 1995), with the four BRIC antibodies and two other monoclonal antibodies to the Kell-glycoprotein, LM705 and LM708 (kindly provided by Drs R. Fraser and G. Inglis, Glasgow and West of Scotland Transfusion Service). Anti-K18 only blocked BRIC 18; anti-K23 and anti-TOU blocked BRIC 18 and BRIC 68; anti-Kp a , -Kp b , -Kp c and -VLAN blocked BRIC 68, BRIC 203 (which has anti-Kp bc specificity) and LM708; BRIC 107 (which has k-like specificity) was blocked by anti-K, -k, -Ul a , -K12, -K13, -K22 and, to a lesser extent, anti-Js a and -Js b ; and anti-K11 and -K17, and anti-Js a and -Js b blocked LM705.…”