MIMA-9, a valuable antibody for screening for rare donors

Since monoclonal antibodies (Mabs) are potentially available in an unlimited volume, they can be used to screen numerous donor blood samples to identify antigen-negative donors. We have used a Mab (MIMA-9) with characteristics that allow for the simultaneous screening of RBCs of any ABO group for high-incidence antigen-negativity in the Kell and Gerbich blood group systems. MIMA-9, a murine IgG2a antibody, previously shown to facilitate the identification of K+k-, Kp(a+b-), K0, McLeod, or Ge:-3 red blood cells (RBCs), was used in MTS gel cards containing anti-mouse IgG as the second antibody to test 1134 K- donors. Among the 1134 donors tested, we found one Kp(a+b-) and one Ge:-2,-3,4 donor. If random donor samples had been used instead of preselecting for K-, we would have expected to identify two K+k- donors. One reagent (MIMA-9) can be used to simultaneously screen for K+k-, Kp(a+b-), K0, McLeod, and Ge:-3 RBCs and thereby conserve rare antisera. Inclusion of anti-mouse IgG in gel cards allowed for rapid screening. MIMA-9 is also a useful reagent to type RBCs with a positive direct antiglobulin test. This antibody is available to donor screening laboratories at no cost for this specific use.