Which sample would be unacceptable for HLA phenotyping by serology?

The sample collected in EDTA is unacceptable for HLA phenotyping by serology due to the effect of EDTA on the detection of antibodies. EDTA functions as an anticoagulant by chelating calcium ions, which are essential for the function of certain enzymes and mechanisms involved in serological assays. This can hinder the activation of complement and other immune reactions that are crucial for accurately assessing HLA antigens and antibodies in the sample.

For HLA phenotyping, the sample must provide reliable and accurate results, and the presence of EDTA can interfere with the necessary serological reactions needed for this assessment. In contrast, blood samples collected in sodium heparin, CPDA-1, or ACD solution B do not exhibit the same level of interference and are thus considered suitable for serological testing.