USE OF THE DAF ASSAY TO ASSESS THE FUNCTIONAL-PROPERTIES OF POLYCLONAL AND MONOCLONAL RH-D ANTIBODIES

The mechanism whereby passive Rh (D) immunoglobulins suppress the feto -maternal alloimmunization is still unclear, New in vitro tests are ne eded to better characterize the functional properties of polyclonal an ti-Ds. The DAF assay was developped to monitor the antibody-dependent cell-mediated cytotoxicity (ADCC) and the phagocytosis of anti-Rh (D)- sensitized RBCs by effector cells, The principle of this test is based on the oxydization of the 2,7-diaminofluorene (DAF) by the pseudopero xidase activity of free hemoglobin. The reaction is proportional to th e hemoglobin concentration, This test was performed to determine and e mphasize the efficacy of different polyclonal anti-D immunoglobulin pr eparations to mediate lysis and phagocytosis of sensitized RBCs by hum an peripheral mononuclear cells, The functional properties of differen t human RhD monoclonal antibodies were also analyzed and compared. The test was found to be convenient to perform and allowed the avoidance of radioactive labelling of RBCs for ADCC studies, It is mainly useful for the direct quantitation of phagocytosis.