Final answer:
MHC class II molecules, including HLA-DP, DQ, and -DR, present antigens to CD4 T-cells and are expressed on professional antigen-presenting cells such as macrophages, dendritic cells, and B cells.
Step-by-step explanation:
MHC class II molecules, specifically HLA-DP, DQ, and -DR, present antigens to CD4 T-cells. These molecules are involved in the adaptive immune response and are expressed on professional antigen-presenting cells such as macrophages, dendritic cells, and B cells.