Table 1.

Examples of ABO mismatches^a

Recipient ABO type	ABO-major mismatched (recipient has isohemagglutinins against ABO antigens on donor PLT)	ABO-minor mismatched (donor has isohemagglutinins against ABO antigens on recipient RBC)
A	B, AB	B, O
B	A, AB	A, O
AB	none	A, B, O
O	A, B, AB	none

^aNote that as group AB recipients lack anti-A and –B, a major mismatched PLT transfusion cannot occur, and as group O PLTs lack A or B antigens, a minor mismatched transfusion cannot occur.