APTITUDE OF MONOCLONAL REAGENTS FOR BLOOD -GROUP ANTIGEN DETERMINATION IN THE CASE OF T-ACTIVATION

Background: The lack of additional antibodies - for example anti-T - w hich can be contained in test sera of human origin has been pointed ou t as an advantage of monoclonal reagents in blood group serology. It w as the aim of our study to examine whether the reactions of monoclonal reagents are nevertheless disturbed by T activation of red blood cell s or not. Materials and Methods: Monoclonal reagents of several manufa cturers of the specificities anti-A, -B, -AB, -A(1), -H, -C, -c, -D, - E, -e, -K, -Jk(a), -Jk(b), -Le(a), -Le(b), -M, and -N were tested. For this study we examined sialidase-treated and not treated red blood ce lls with and without the tested blood group antigen by the reagent usi ng the tube centrifugation method. Results: We found no significant di sturbances for the monoclonal reagents of the AB0-system, A subgroups, Rhesus system, Kidd system, Kell antigen, and Le(b) antigen. Monoclon al anti-M and anti-N showed missing reactivity with sialidase-treated erythrocytes, which is already known from polyclonal test sera. Most o f the monoclonal anti-Le(a) reagents showed strong false-positive reac tions with T-positive Le(a-) erythrocytes. After several absorptions o f one of the monoclonal anti-Le(a) reagents with T-activated Le(a-b-) red blood cells, the reactivity of the reagent with the Le(a) antigen and the T antigen had disappeared. Conclusions: In contrast to the oth er monoclonal reagents for most of the monoclonal anti-Le(a) reagents the lack of additional anti-T antibodies does not indicate the lack of false-positive reactions. This cross-reactivity might be caused by th e fact that the type 1 chain antigen Le(a) and the type 3 chain antige n T have the same terminal saccharide (galactose) in beta 1 --> 3 conn ection to the preterminal saccharide of their peripheral core structur e.