Predicting the clinical significance of red cell alloantibodies using a monocyte monolayer assay

Few data have been published that correlate in vitro monocyte monolayer assays (MMA) and red cell (RBC) survival in patients with alloantibodies of unknown significance. Over the past 6 years we gathered clinical correlations in 12 patients with the following antibodies: anti-Lan (three patients), -Ge (three patients), -Yta (five patients), and -Ytb (one patient). RBC survival was estimated using 51Cr studies in seven patients and follow-up of transfusion of incompatible blood in the other five. Six patients with no evidence of RBC destruction had negative MMA findings (anti-Lan [one patient], -Ge [two patients], and -Yta [three patients]). Five patients with evidence of in vivo RBC destruction had significant MMA results. The two clinically significant anti-Lans required fresh serum to give a meaningful MMA result. One patient (anti-Ytb) had an MMA result of borderline significance--normal 51Cr RBC survival at 1 hour--but a reduced T50Cr. The MMA we used appeared to predict the clinical outcome of transfusion in every patient with antibodies to high-frequency antigens whom we tested.