Cross‐linking induces non‐haemolytic antigen‐loss from transfused red blood cells: a potential role for rheumatoid factor

Transfusion of cross‐match incompatible blood can lead to haemolysis. However, in some cases, incompatible transfused red blood cells are bound by antibody and then converted to being negative for both the incompatible antigen and the direct antiglobulin test. Using a murine model of this phenomenon, we have recently reported that antibodies binding to multiple epitopes are required. Herein, we report that antibodies against one epitope can induce antigen‐loss if an anti‐immunoglobulin G (IgG) antibody is also present. These findings support a model of cross‐linking being required, and raise the possibility that naturally occurring anti‐IgG, such as rheumatoid factor, may contribute to antigen‐loss.