Correct option is C
Explanation:
Statement A: Antigen/MHC-II complexes on CD4 T cells interact with antigen/MHC-I complexes on CD8 cells.
- This statement is incorrect. CD4 T cells recognize antigens presented by MHC-II molecules, while CD8 T cells recognize antigens presented by MHC-I molecules. Therefore, there is no direct interaction between MHC-II on CD4 T cells and MHC-I on CD8 T cells.
Statement B: A single dendritic cell (DC) presents antigen on MHC-I and MHC-II at the same time.
- This statement is correct. A single dendritic cell can indeed present antigens on both MHC-I and MHC-II molecules simultaneously, allowing the DC to interact with both CD8 T cells and CD4 T cells.
Statement C: CD4 T cells activate DCs which produce chemokines like CCL3 and CCL4 that can specifically attract CD8 T cells to form a CD4-CD8-DC triad.
- This statement is correct. CD4 T cells activate dendritic cells (DCs), which then produce chemokines like CCL3 and CCL4, attracting CD8 T cells and forming a CD4-CD8-DC triad. This is crucial for effective activation of CD8 T cells.
Statement D: CD4 T cells help B cells, which differentiate into plasma cells and secrete antibodies that form immune complexes which bind to FcγRs on CD8 T cells.
- This statement is incorrect. While it is true that CD4 T cells help B cells differentiate into plasma cells and secrete antibodies, FcγRs on CD8 T cells do not bind to immune complexes formed by antibodies from plasma cells in the context described here. The main function of CD4 T cells in this context is more related to activating B cells to produce antibodies, rather than directly activating CD8 T cells via immune complexes.
Conclusion:
The correct combination of statements is B and C, as both are accurate in describing the interaction between CD4 T cells, dendritic cells, and CD8 T cells.
