Although many second messengers have been shown to be necessary and sufficient for T cell activation in a number of model systems , the rate-limiting step in peripheral T cells has not been demonstrated .
although many second messengers have been shown to be necessary and sufficient for t cell activation in a number of model systems , the rate-limiting step in peripheral t cells has not been demonstrated .
O O B-other_organic_compound I-other_organic_compound O O O O O O O O O B-cell_type I-cell_type O O O O O O O O O O O O B-cell_type I-cell_type I-cell_type O O O O O