A potent cold autoagglutinin that recognizes type 2H determinant on red cells

Area of Science:

• Immunology
• Hematology
• Blood group serology

Background:

• Cold autoagglutinins are antibodies that bind to red blood cells at cooler temperatures.
• The ABO blood group system is crucial for blood transfusions and understanding immune responses.
• Type 2H determinants are specific carbohydrate structures on red blood cells that can be targeted by antibodies.

Observation:

• A patient presented with a positive direct antiglobulin test due to C3d complement component on red blood cells.
• The patient's serum contained an immunoglobulin M (IgM) lambda antibody.
• This antibody demonstrated cold autoagglutinin activity, being active at 37°C and showing similar agglutination at 4°C.

Findings:

• The autoagglutinin specifically targeted the Type 2H determinant within the ABO blood group system.
• The antibody preferentially agglutinated group O red blood cells.
• Reactivity was absent against Bombay (Oh) red blood cells, further defining the specificity.
• Adsorption studies using synthetic oligosaccharide immunoadsorbents confirmed the antibody's specificity.

Implications:

• This case provides a detailed characterization of a rare IgM cold autoagglutinin.
• Understanding such specificities is vital for accurate blood banking and transfusion practices.
• The findings contribute to the broader knowledge of immune system interactions with red blood cell antigens.