Detection of Rh antigen expression on iRBCs by gel column agglutination. (A) Rh antigen typing of DCe/DCe (R1R1), DcE/cE (R2R2), and ce/ce (rr) esRBCs or iRBCs using commercial monoclonal RBC typing reagents for the 5 common Rh antigens (anti-D, anti-C, anti-c, anti-E, and anti-e indicated above) on buffered gel cards. Agglutination prevents cells from traveling through the gel matrix to the bottom of each column upon centrifugation and indicates cell surface expression of the corresponding antigen. (B-D) (B) Rh typing for common Rh antigens of Rh null, D--, D⁺ Go^a+, and D⁺ DAK⁺ iRBCs, and (C) D⁺c⁺e⁺, VVS⁺ iRBCs, and (D) C⁺c⁺e⁺, hr^B− and D⁺c⁺e⁺, hr^S− ficin-treated iRBCs.