Hemolytic anemia associated with multiple autoantibodies and low serum complement.

Area of Science:

• Hematology
• Immunology
• Clinical Medicine

Background:

• Extravascular hemolytic anemia can be associated with various autoantibodies.
• Characterizing multiple autoantibody types and their complement fixation is crucial for understanding disease mechanisms.

Purpose of the Study:

• To investigate the types and characteristics of multiple red blood cell autoantibodies in a patient with hemolytic anemia.
• To determine the role of complement system activation in the pathogenesis of the patient's condition.
• To correlate autoantibody findings with clinical response to treatment.

Main Methods:

• Positive Monospot test, antiglobulin and anticomplement Coombs' tests, cold agglutinins, and warm autoantibodies were assessed.
• Elution of IgG-kappa antibodies from patient's red blood cells.
• Adsorption of patient's serum with heterologous red cell stroma at different temperatures to elute various immunoglobulin and complement components.
• Determination of serum complement component titers (C3, C4, C5).
• Localized cold stress test and clinical response to prednisone.

Main Results:

• Multiple autoantibodies including IgM-kappa, IgM-lambda, IgG-3-kappa, IgG4-lambda, IgA-lambda, and C3 were identified, reacting optimally at low temperatures.
• Cold-reactive IgG3-kappa antibodies were capable of interacting with red cells at 37°C, explaining eluted IgG-kappa.
• Decreased C4, C3, and C5 titers indicated complement fixation by IgM and/or IgG3-kappa antibodies.
• Cold stress test showed increased plasma hemoglobin and decreased C3.
• Patient showed a beneficial clinical response to prednisone.

Conclusions:

• The patient presented with multiple red blood cell autoantibodies, including cold-reactive IgG3-kappa, which were pathophysiologically significant.
• Complement fixation by these autoantibodies likely contributed to the hemolytic episode.
• This case highlights the importance of comprehensive characterization of autoantibodies and complement components in hemolytic anemia.
• Subclinical infectious mononucleosis may have preceded the hemolytic episode.