HLA class II antigens (DP, DQ, & DR) present antigens from outside of the cell to T-lymphocytes. These particular antigens stimulate T-helper cells to reproduce, and these T-helper cells then stimulate antibody-producing B-cells. Self-antigens are suppressed by suppressor T-cells. HLA-DR typing becomes important before organ transplantation, to prevent the rejection of grafted tissues. See also HLA-DR, Flow Cytometry
Collect in EDTA vacutainer tube. Avoid contamination with DNA of phlebotomist and send tube unopened. Avoid haemolysed samples. Do not freeze samples. Patient should not receive blood transfusions for at least 3 weeks.