Studies on the blood group antigen Ina

Area of Science:

• Immunology
• Transfusion Medicine
• Blood Group Serology

Background:

• The Ina antigen is a blood group antigen present at birth, though its expression can be weaker and fluctuate during pregnancy.
• Anti-Ina antibodies have been detected in individuals hyperimmunized with In(a+) blood and in Rh-immunized women.

Purpose of the Study:

• To characterize the prevalence, properties, and clinical significance of anti-Ina antibodies.
• To investigate the potential for anti-Ina antibodies to cause transfusion reactions.

Main Methods:

• Serological testing of hyperimmune donors and Rh-immunized women.
• Characterization of antibody reactivity using various media and indirect antiglobulin tests.
• Complement binding assays and biochemical analysis (2-mercaptoethanol, DEAE-column chromatography) to determine antibody class.
• In vivo studies to assess red blood cell clearance in the presence of anti-Ina.

Main Results:

• Anti-Ina antibodies were found in 30/41 anti-Rh donors and 4/60 Rh-immunized women.
• The Ina antigen's strength varies with age and pregnancy.
• Antibodies were confirmed as IgG class, complement-binding, and reactive across multiple test conditions.
• Transfusion of In(a+) red cells into individuals with anti-Ina resulted in rapid elimination within 20 minutes.

Conclusions:

• Anti-Ina antibodies are predominantly IgG and can cause rapid destruction of In(a+) red blood cells.
• Although not definitively linked to hemolytic disease of the newborn in this study, anti-Ina antibodies pose a significant risk for transfusion reactions.