[Capture-R Ready-ID and DiaMed-ID for identification of erythrocyte bound antibodies after acid elution].

Abstract

The DiaMed-ID (D-ID) gel system is known to be a very sensitive and specific method for the detection of red cell antibodies. In various cases, we failed to find an antibody in the eluate in which red-cell-bound antibodies (IgG) where proven by a positive direct antiglobulin test (DAT). SPRCA (Capture-R, Ready Screen, Immucor; C-R) seems also to be very sensitive, in part due to the antihuman, IgG-coated indicator cells. Therefore, we compared 39 acid eluates from patients who had a positive DAT (monospecific rabbit antihuman IgG) both in the D-ID and in the C-R system. Patients (19 female, 20 male; mean age 62 years) were suspected either to have an autoimmune hemolytic anemia or an alloantibody. Identification of the antibodies was done with the system's own panel cells. Agglutination strength was scored from 1 to 4. Quantification of selected eluates was performed by titration, using the same cells in both systems. From 39 eluates, 31 were positive in the C-R and 25 in the D-ID. Nine eluates were negative in the C-R and 14 in the D-ID. If only eluates with a DAT reaction strength of 2 or lower were considered, obviously more negative results were found with the D-ID technique (p < 0.027) than with the C-R technique. In all eluates the degree of test reaction was stronger in the C-R system. However, titration endpoints of 6 quantified antibodies did not differ significantly. In 2 patients with slightly positive DAT, antibody typing was negative or not clear in the serum. In the corresponding eluates, an anti-K and an anti-JKa could be identified only by the C-R technique. In such instances we recommend to use the C-R technique to prevent transfusion complications.