Before revision:  While the clonal selection of the T helper (Th) cells is the simple and established mechanism for learning a better recognition of new pathogens, the question  still remains unexplored is how the Th cells can learn to eliminate them by activating or deactivating appropriate immune cells after recognition .
After revision:  While the clonal selection of the T helper (Th) cells is the simple and established mechanism to better recognize new pathogens, the question still remains unexplored is how the Th cells can learn to eliminate them by activating or deactivating appropriate immune cells after recognition .