Mary requires a kidney transplant. To determine which member of her family is most suitable as a kidney donor, an HLA serological typing of the family was performed. The results are as follows: Mary: HLA-A12, A3, B6, B8, DR2, DR4 Mary's brother: HLA-A12, B6, B37, DR2 Mother: HLA-A3, A12, B8, B37, DR2, DR4 Father: HLA-A12, A20, B6, B27, DR2, DR3 1. HLA molecules are codominantly expressed. Explain. 2. Mary's cell express both HLA-A3 and an HLA-A12. Her brother's cell express only HLA-A12. How is this possible if the HLA proteins are codominantly expressed? 3. Mary requires a kidney transplant. If Mary were to receive a kidney from her father, what anti-HLA antibodies would she generate? From her brother? From her mother?