Table 3.

Comparison of methods used to identify compatible platelet units for alloimmunized patients

	Crossmatched	HLA matched	HLA compatible
Method	Test patient’s serum against a panel of platelets to determine compatibility	Identify platelet donors with perfect (4/4) match for patient’s HLA class IA and IB alleles	ASP: Use antibody specificities to select donor units that lack corresponding antigens
Pros	• Rapid turnaround-time	• 4/4 match ensures HLA compatibility	• Larger donor pool
	• Obtain compatible units without HLA genotype or HLA antibody testing	• Reduced risk of future alloimmunization	• Reduced risk of future alloimmunization
	• Compatible with HLA and HPA antibodies
Cons	• Difficult to find compatible units for highly alloimmunized patients	• HLA genotyping required	• Not useful for HPA antibodies
	• Risk of alloimmunization for mismatched HLA antigens	• Limited donor pool for some patients	• HLA antibody testing required

Table adapted from Forest and Hod.¹

ASP, antibody specificity prediction.