Altered antibody repertoires of plasma IgM and IgG to nard nonself antigens in patients with warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (WAIHA) is characterized by an accelerated extravascular clearance of red blood cells (RBC) mediated by RBC-bound IgG autoantibodies. We have recently demonstrated significantly altered self-r eactive antibody (Ab) repertoires of plasma IgM in WAIHA patients. The natu ral IgM Ab repertoire in plasma is critical in modulating both autoimmune a nd alloimmune responses. In the present study, we investigated IRM and IgG Ab repertoires of WAIHA patients toward nonself antigens (Ag) using a quant itative immunoblotting technique, followed by multiparametric statistical a nalysis of the data. We demonstrate significantly altered Ab repertoires of IRM and IgG toward nonself Ag in WAIHA patients. The reactivity of plasma IgM of WAIHA patients was reduced compared to char of healthy individuals, independent of administering an immunosuppressive therapy. We observed that an increase in reactivity of plasma IgM during clinical remission of the d isease was associated with the development of allo-Ab toward RBC-antigens d uring RBC transfusions. Taken together, the data indicate altered Ab repert oires of plasma IgM and IgG toward nonself Ag in WAIHA patients. A broadly reduced reactivity of plasma IgM toward nonself Ag might influence the adap tive immune response in WAIHA patients. (C) American Society for Histocompa tibility and Immunogenetics, 2001. Published by Elsevier Science Inc.