Production and characterization of anti-kell monoclonal antibodies using transfected cells as the immunogen.

Monoclonal antibodies (Mabs) to blood group antigens are valuable as diagnostic reagents for typing red blood cells (RBCs) in the clinical setting, and for structure-function studies of proteins. Here, we report a powerful system that enabled us to produce Mabs to blood group antigens. A murine erythroleukaemia (MEL) cell line expressing Kell protein, a transmembrane glycoprotein that carries a number of clinically relevant antigens, was used as a novel immunogen. Mabs with different specificities to the Kell protein were produced from a single mouse fusion: an anti-Jsb (MIMA-8), and two antibodies (MIMA-9 and MIMA-10) with novel specificities, that reacted with RBCs with the common Kell phenotype but not with RBCs with K+k- or Kp(a+b-) or K0 phenotypes. The non-reactivity with both K+k- or Kp(a+b-) RBCs implied that the epitope was influenced by the molecular changes associated with an absence of the k or Kpb antigens. MIMA-8 is the first example of a Mab anti-Jsb and was used in the clinical laboratory for screening donor RBCs for Js(b-) blood and for typing RBCs from patients even when the RBCs were coated with anti-IgG as is the case in autoimmune haemolytic anaemia. Heavy and light chain variable regions of MIMA-8 were cloned and the sequence is given. This study illustrates the potential of this novel immunization approach for making monoclonal antibodies to blood group antigens.