A schematic view of anti–blood group A Ab-producing cell development and strategy for the persistent elimination of these cells by using synthetic blood group A carbohydrates conjugated with BSA, anti-BSA Abs, and CsA. Synthetic A carbohydrates conjugated with BSA target already differentiated B cells and Ab-producing cells with anti–A carbohydrate specificity. The subsequently administered anti-BSA Abs bind the BSA epitopes of A carbohydrate BSA binding to B cells with anti-A specificity. This Ag-Ab binding leads to specific elimination of anti–A carbohydrate IgM-producing cells and their precursor B-1 cells. Stimulation with group A carbohydrate determinants leads to the differentiation of new B-1 cells with anti-A specificity; however, this differentiation is blocked by CsA.