A radiolabeled antiglobulin test for crossmatching platelet transfusions

Area of Science:

• Immunology
• Transfusion Medicine
• Hematology

Background:

• Alloimmunized patients often experience platelet transfusion failures despite HLA-matched platelets.
• Refractory patients require improved methods for selecting compatible platelet transfusions.

Purpose of the Study:

• To evaluate a radiolabeled antiglobulin technique for platelet crossmatching in alloimmunized patients.
• To determine if the radioactivity antiglobulin test (RAGT) can predict transfusion success.

Main Methods:

• A 125I-labeled goat anti-human IgG indirect Coombs test was used for platelet crossmatching.
• The radioactivity antiglobulin test (RAGT) index was calculated to assess compatibility.
• Transfusion effectiveness was measured by corrected platelet count increment (CCI) at 1 and 20 hours in 19 refractory patients.

Main Results:

• Platelet transfusions with a RAGT index ≤ 1.9 showed significantly higher mean CCI at 1 hour (17,570/cu mm) and 20 hours (8,722/cu mm) compared to those with an index ≥ 2.0 (4,237/cu mm at 1 hr, 571/cu mm at 20 hr).
• One false negative and nine cases with good initial increments but zero survival at 20 hours were observed.
• The RAGT demonstrated a strong correlation between crossmatch results and transfusion outcomes.

Conclusions:

• The radiolabeled antiglobulin technique is a valuable tool for selecting compatible platelets in refractory, alloimmunized patients.
• This method aids in reducing platelet transfusion failures by identifying incompatible units.
• Further refinement may improve accuracy and minimize false negatives.