What is the purpose of using a 'wash' step in the preparation of red blood cells for crossmatching?

A To remove plasma proteins and reduce the risk of an allergic reaction ✓
B To remove white blood cells and reduce the risk of graft-versus-host disease
C To remove platelets and reduce the risk of thrombosis
D To remove preservative solutions and reduce the risk of toxicity

Explanation

The wash step is used to remove plasma proteins, which can interfere with crossmatching reactions and increase the risk of an allergic reaction. This step helps to ensure the accuracy and safety of the crossmatch.

Source

AABB Technical Manual
Hematology Hematology: Blood Grouping and Crossmatching Hematology: Blood Grouping and Crossmatching Easy MEDICAL Confidence: high