Anti-C^w alloantibodies: Case series highlighting diagnostic challenges and variability

Anti-C^w antibody against the red cell C^w antigen, which is a low-frequency antigen in the Rh-Blood Group System. Routine testing for this antibody is not commonly performed in many transfusion centres.

This study aimed to describe six cases where Anti-C^w antibodies were detected among both blood donors and a patient, highlighting their variable presentation and potential clinical significance.

This retrospective study on six cases presented with Anti-Cw alloantibody routinely tested for irregular antibodies using antibody screening and identification panels by column agglutination technique and conventional tube technique. Identified antibodies were confirmed using select cell panels and extended Rh phenotyping. The thermal amplitude and phase of the reaction were determined to characterize the antibodies. Donor and patient RBC typing for C^w antigen was performed with in-house available polyclonal Anti-C^w antibody of IgG type.

Data was reviewed from January 2021 to December 2023, and Anti-C^w antibody was found of IgG type in five donors among 29513 blood donors and an IgM type antibody in one patient among 15346 patients during that period. Notably, all the donors had no history of blood transfusion and had IgG antibodies, and one female patient with a positive obstetric history had IgM type of Anti-C^w alloantibody.

This study showcases the variable presentation of Anti-C^w antibodies, which could lead to transfusion challenges in recipients and donors. It also highlights the need for the detection of clinically significant alloantibodies, including Anti-C^w antibody in transfusion recipients, to avoid adverse transfusion events.