A chemiluminescence test for predicting the outcome of transfusing incompatible blood

A chemiluminescent test (CLT) which measures the metabolic response of huma n monocytes to sensitized red cells was developed to distinguish antibodies capable of causing the increased destruction of transfused incompatible re d cells from antibodies which are clinically benign. Thirty sera containing IgG antibodies to high-frequency antigens were tested; 27 of these sera we re also tested using the monocyte monolayer assay (MMA). The clinical signi ficance of antibodies in 14 of the sera was known: three (anti-At-a (two), -JMH) caused accelerated clearance of Cr-51-labelled cells, five (anti-'MiI II', -Yt(a), three unidentified) caused haemolytic transfusion reactions an d six (anti-Yt(a), -Ge, -JMH, -Xg(a), -Kn(a) (two)) did not appear to affec t red cell survival. Overall, results from the MMA and CLT showed good agre ement; seven sera were negative in both assays, 18 sera were positive in bo th assays and two sera were positive in the MMA but negative in the CLT. Th ere was no clear relationship between the activity of different antibodies and the level of sensitization as determined by flow cytometry. Antibody ac tivity could be either increased or decreased by incubation of sensitized r ed cells with fresh serum. MMA results were in concordance with the clinica l significance of antibodies where known in eight of 10 cases. CLT results were in concordance with clinical significance in 12 of 14 cases. Both assa ys gave false-positive results with serum from a patient with anti-Kn(a) wh o had received red cell transfusions without adverse effect. This appeared to be due to the ability of anti-Kn(a) to cross-link complement receptor 1 (CR1) on red cells to CR1 on monocytes; negative results were obtained usin g autologous monocytes.