Disulfide bonds are a requirement for Kell and Cartwright (Yta) blood group antigen integrity

We have investigated the effect of dithiothreitol (DTT) upon the Kell blood group system and other red cell antigens. All Kell blood group antigens studied (K, k, Kpa, Kpb, Jsa, Jsb and Ku) as well as the Cartwright (Yta) antigen were completely denatured after treatment with DTT. The Gerbich antigen was substantially weakened but not completely denatured. The Jsa and Jsb antigens appear to have an exquisite sensitivity to treatment with DTT and can be completely denatured using very low concentrations (less than or equal to 2 mM) whereas other Kell system antigens require much higher concentrations of DTT for their denaturation (100-200 mM). Of 38 other blood group antigens investigated, only the Yta antigen was completely denatured using 200 mM DTT. Furthermore, the Yta antigen was denatured within the same concentration range as Kell and one can speculate that this indicates some biochemical relationship between these two blood group systems. From our results, we conclude that: (1) at least two distinct disulfide (S-S) bonds are required for maintenance of the Kell blood group antigen system; (2) Jsa and Jsb antigens are distinctly different from other Kell system antigens based upon sensitivity to treatment with DTT; these antigens may be located on a different antigenic domain; and (3) the Yta antigen requires at least one disulfide bond for its maintenance of antigen integrity. Although the Gerbich antigen was not completely denatured, results indicate that disulfide bonds may also be important structural determinants for these antigens.