[Solid phase technique versus gel centrifugation for detection of erythrocyte antibodies--a prospective study...

To define differences of specifity and sensitivity between a solid phase- and a gel centrifugation test for detection of irregular erythrocyte antibodies.

3052 blood samples were screened for erythrocyte antibodies (AB) by gel centrifugation [ID-System, (ID) 37 degrees C Bromelin and indirect antiglobulin test with LISS (IAT)] and a solid phase antiglobulin test [Capture-R Ready Screen (CR)] in a prospective study. Identical test cells were used as immobilized monolayer in CR and as 1%-suspension in ID. Additionally, 42 sera with antibodies reacting in both tests were titered geometrically in both techniques.

In 79 (2.6%) of all sera tested, irregular erythrocyte antibodies were detected. 64 (81%) of these positive sera were detected by both tests, 73 (92.3%) by ID and 70 (88.4%) by CR. 6 sera with AB (7.6%) were positive only with CR (1 Ce, 1 E, 1 Leb, 1 C, 1 D, 1 Cob) and 9 (11.4%) only with ID (4 Lea, 1 Fya, 1 C, 2 P1, 1 D). Seven AB solely detected in ID only reacted in the bromelin test, besides an anti-Fya, which was an IgM antibody. The titration of IgG antibodies showed a slightly higher sensitivity of the CR (less than one titre step). The ID showed clearly more unspecific reactions (1.1%) than the CR (0.5%).

The antibody screening with the ID proved to detect more AB than the CR (mainly due to certainly irrelevant "enzyme only" AB). On the other hand, relevant IgG AB were detected more sensitive by the CR. Unspecific reactions appeared clearly more often in ID, predominantly when using the bromelin test. Missing a strong IgM anti-Fya in the CR is certainly a concern because of its assumed haemolytic activity. Therefore CR for antibody screening should always be combined with a method for crossmatching that safely detects IgM antibodies which are relevant for transfusion.