Final answer:
The statement 'MHC class II molecules are found on antigen-presenting cells' is true. MHC class II molecules are exclusively present on professional antigen-presenting cells such as macrophages, dendritic cells, and B cells. MHC class I, however, is found on all nucleated cells.
Step-by-step explanation:
MHC class II molecules are indeed found on antigen-presenting cells like macrophages, dendritic cells, and B cells. This makes the statement 'MHC class II molecules are found on antigen-presenting cells' true.
The role of MHC class II is crucial in the immune system, as it presents antigenic peptides to CD4+ T helper cells. It's important to note that while MHC class II is limited to these professional antigen-presenting cells, MHC class I molecules are expressed on all nucleated cells, which present antigens to CD8+ cytotoxic T cells.
Furthermore, the statement that 'MHC II is a receptor found on most body cells', is false. It is actually MHC class I that is found on all nucleated cells, and MHC class II is restricted to the professional antigen-presenting cells mentioned above.