Naturally Occurring Anti-Jk^a: Expanding the Evidence beyond Sensitization

Area of Science:

• Transfusion Medicine
• Immunology
• Blood Banking

Background:

• Red blood cell (RBC) alloantibodies usually develop after transfusion or pregnancy.
• Naturally occurring antibodies arise without sensitization, often targeting ABO or Lewis antigens.
• Kidd system antibodies are clinically significant, typically IgG, and rarely occur naturally.

Purpose of the Study:

• To investigate the occurrence and detection of naturally occurring anti-Jkª antibodies.
• To evaluate the efficacy of different serological methods in identifying these antibodies.

Main Methods:

• Routine pretransfusion testing using automated hemagglutination and manual tube methods.
• Antibody screening via standard three-cell panel and solid-phase red cell adherence (SPRCA).
• Phenotyping and comparative testing using indirect antiglobulin test (IAT) with PEG enhancement.

Main Results:

• Two patients presented with anti-Jkª detected by SPRCA, despite no history of transfusion or pregnancy.
• A dosage effect was observed with anti-Jkª in SPRCA, but IAT with PEG enhancement failed to detect it.
• Auto-controls and direct antiglobulin tests were negative, with no other significant antibodies identified.

Conclusions:

• Anti-Jkª can arise naturally, independent of known sensitizing events.
• SPRCA is effective in detecting weak or developing antibodies missed by conventional tube methods.
• Awareness of naturally occurring Kidd antibodies is crucial for accurate blood selection in transfusions.