Which sample is preferred for molecular testing of class II HLA antigens?

The preferred sample for molecular testing of class II HLA antigens is peripheral blood in EDTA. This choice is favored primarily because EDTA acts as an anticoagulant, preventing blood from clotting and thus preserving the integrity of the leukocytes in the sample.

When testing for HLA class II antigens, functional and genomic analysis requires intact lymphocytes. Peripheral blood, when collected with EDTA, maintains the cells in a state suitable for molecular assays, such as PCR or sequencing. The leukocytes can readily be isolated from the whole blood for further genetic analysis.

Moreover, using peripheral blood minimizes the need for complex processing or manipulation that might compromise cell viability or DNA integrity. The use of EDTA ensures that the blood remains in a liquid state, which allows for optimal cellular handling. Other methods of sample preparation, like Ficoll separation or transformed B cell lines, may introduce variables that are less desirable for molecular testing or may not represent the natural population of HLA class II antigens in an individual's immune system as effectively.