Since the description of the RhD antigen by Levine and Stetson in 1939, more than 40 other Rh antigen complexes have been identified. Apart from D the other major Rh antigens are C, E, c and e. The C^w antigen is one of the more rare antigens but Anti-C^w is a fairly common encountered antibody. Used separately, anti-Rh blood grouping reagents will indicate whether an individual expresses the corresponding antigen – an essential procedure in the determination of antibody specificity and selection of blood for transfusion of patients with Rh antibodies. Testing red cell samples with anti-C, anti-D, and anti-E, anti-c and anti-e will disclose the Rh phenotype from which the most probable genotype may be deduced.

The Biorex Diagnostics Anti-C^w blood grouping reagent contains human monoclonal IgM antibody, diluted in a phosphate buffer containing sodium chloride, bovine albumin and a preservative. This reagent is supplied ready for use and does not require any further dilution or addition.