Incomplete Antibodies May Reduce ABO Cross-Match Incompatibility: A Pilot Study

Area of Science:

• Immunology
• Transfusion Medicine
• Biochemistry

Background:

• Erythrocyte transfusions for individuals with blood types A or B are contraindicated due to potentially fatal antibody-mediated complications.
• Cross-match tests are essential to prevent immune transfusion reactions prior to blood administration.

Purpose of the Study:

• To evaluate the efficacy of incomplete antibodies, specifically the fragment antibody (Fab) portion, in mitigating immune responses during cross-match tests.
• To explore the potential of Fab (2) fragments in preventing transfusion complications.

Main Methods:

• Monoclonal anti-A and anti-B antibodies were fragmented into Fab (2) using pepsin and purified via staphylococcal protein A columns.
• Cross-match tests were conducted using tube and gel centrifugation methods, combining erythrocytes with purified anti-A or anti-B Fab (2) solutions.
• Agglutination levels were quantified to assess the impact of Fab (2) antibodies compared to complete antibodies.

Main Results:

• No agglutination was observed in tube cross-match tests using purified anti-A Fab (2) with A Rh+ erythrocytes and anti-B Fab (2) with B Rh+ erythrocytes.
• Gel centrifugation tests showed minimal agglutination (1+).
• Erythrocytes treated with Fab (2) fragments demonstrated resistance to agglutination by complete antibodies.

Conclusions:

• Fab (2) antibody fragments can elicit reduced or negative reactions compared to complete antibodies.
• These incomplete antibodies hold promise for decreasing ABO incompatibility and may serve as a therapeutic option for conditions like autoimmune hemolytic anemia.
• Further in vivo studies are planned to validate these in vitro findings for potential applications in transplantation.