Reduced response to group A determinants and preserved normal response to other human RBC antigens in mice that received A-BSA/anti-BSA Abs and CsA treatment. Mice that were either untreated or treated with CsA alone or A-BSA/anti-BSA Abs along with CsA were intraperitoneally immunized with 5 × 108 A-RBCs 8 and 9 weeks after the injection of A-BSA/anti-BSA Abs. At 8 days after the last immunization, the levels of anti-human RBC Ab (IgM) in the sera of these mice were determined by FCM analysis for evaluating the indirect immunofluorescence staining of human A-RBCs and O-RBCs (10 weeks after A-BSA/anti-BSA Ab injection). (A) Representative histograms obtained by FCM analysis show a reduced response to group A determinants and a preserved normal response to other human RBC antigens in mice that received A-BSA/anti-BSA Abs and CsA treatment. The dotted lines represent the negative control staining of human A-RBCs with secondary mAb alone (PE-conjugated rat anti–mouse IgM mAbs). Thin and solid lines represent staining of human O-RBCs and A-RBCs, respectively, with 20-fold–diluted mouse serum plus PE-conjugated rat anti-mouse IgM mAbs. (B) The ratio of the median fluorescence intensity of staining of A-RBCs to that of O-RBCs represents the anti-A determinant Ab level. Average values (± SEM) for the individual groups are shown. The number of animals in each group was as follows: untreated control, n = 5; mice receiving CsA alone, n = 4; mice receiving a single injection of A-BSA/anti-BSA Abs and daily administration of CsA, n = 5. *P < .05.
