S1PR1 and infection: Not surprisingly, mice deficient in lymphocytes failed to control parasite growth at the infection site (Fig. 5c), and retention of lymphocytes in the secondary lymphoid organs of infected C57BL/6 mice by S1P1 downregulation via FTY720 (fingolimod) treatment also interfered with the control of parasite load at the infection site (Fig. 5d).