Polyreactivity of disease-associated anti-RBC IgG autoantibodies of patients with warm autoimmune haemolytic anaemia and natural anti-RBC IgG autoantibodies of healthy individuals

Anti-red blood cell (RBC) immunoglobulin G (IgG) autoantibodies are present in patients with warm autoimmune haemolytic anaemia (WAIHA), and, as natur al autoantibodies, in healthy individuals. This study investigated whether the feature of polyreactivity discriminates disease-associated from natural anti-RBC IgG autoantibodies. The patterns of reactivity of purified anti-R BC IgG eluted from the RBC of WAIHA patients and from the RBC of healthy in dividuals were analysed using quantitative immunoblotting on a panel of who le human tissue or bacterial cell extracts as antigen sources. In parallel, the reactivity patterns of IgG purified from plasma were analysed. Anti-RB C IgG of WAIHA patients and of healthy individuals recognized a wide range of self- and nonself-antigens. The reactivity patterns of anti-RBC IgG were homogeneous among patients and controls, did not differ between patients a nd controls, and were similar to those of IgG purified from plasma in the c ase of both patients and healthy individuals. The data demonstrate that the anti-RBC IgG autoantibodies of WAIHA patients share extensive similarity w ith those of healthy individuals. Polyreactivity is a common feature of bot h disease-associated and natural anti-RBC IgG autoantibodies.