Effector cells, in order to avoid returning to the lymph nodes:
A. up-regulate chemokine receptors to allow them to home to site of infection.
B. down-regulate L-selectin, so they do not enter the high-endothelial venules (HEVs).
C. down-regulate chemokine receptors, so they do not enter the high-endothelial venules (HEVs).
D. Both A and B.
E. Both B and C.
Answer: D