[Platelet transfusion and immunization anti-Rh1: implication for immunoprophylaxis]

Area of Science:

• Transfusion Medicine
• Immunology
• Hematology

Background:

• Rhesus (Rh) antigens are absent on platelets but present on contaminating red blood cells in platelet concentrates (PC).
• This poses a risk of anti-D iso-immunization, especially in females, due to potential maternal-fetal Rh incompatibility during pregnancy.
• Current guidelines recommend Rh-incompatible transfusions with anti-Rh immunoglobulin for women of childbearing age, but this recommendation is over a decade old.

Purpose of the Study:

• To evaluate the current relevance and necessity of anti-Rh immunoglobulin seroprophylaxis in recipients of Rh-incompatible platelet transfusions.
• To assess the actual risk of anti-D iso-immunization given advancements in product preparation and transfusion practices.
• To determine if existing recommendations require revision based on current data and clinical outcomes.

Main Methods:

• Review and analysis of published data on Rh iso-immunization following platelet concentrate transfusions.
• Assessment of factors influencing immunization risk, including PC preparation methods, patient immune status, and timing of serological testing.
• Consideration of the impact of modern apheresis techniques and the transfusion practices in immunocompromised populations.

Main Results:

• Interpreting existing data is challenging due to heterogeneity in study designs, PC types, and immune status of patients.
• Modern platelet concentrate preparation methods and the prevalence of apheresis have likely reduced the risk of immunization.
• Immunocompromised patients, including those undergoing chemotherapy or hematopoietic stem cell transplantation, may have a reduced risk of developing anti-D antibodies.
• Reported iso-immunization rates vary (up to 19%), but clinical consequences of such immunization have not been documented.

Conclusions:

• The risk of anti-D iso-immunization from Rh-incompatible platelet transfusions may be overestimated.
• Advancements in transfusion technology and practices have potentially mitigated the risk.
• Current seroprophylaxis recommendations warrant re-evaluation and possibly revision towards more targeted indications.