The Kidd antigen system consists of 2 antigens: JK^a and JK^b, which were first reported in 1951 and 1953 respectively. Kidd antibodies are capable of causing severe acute haemolytic transfusion reactions and haemolytic disease of the fetus and new-born. They are unique in that they are capable of dropping to low or even undetectable levels. This Anti-JK^a and Anti-JK^b reagent is for the in vitro detection and identification of the human JK^a and JK^b blood group antigens respectively, by direct agglutination.

The Biorex Diagnostics Anti-JK^a and Anti-JK^b blood grouping reagents contain human monoclonal IgM antibodies, diluted in a phosphate buffer containing sodium chloride and bovine albumin. Anti-JK^a is manufactured with Clone P3HT7 and Anti-JK^b with Clone P3143. This reagent is supplied ready for use and does not require any further dilution or addition.