Antibody response to T-independent antigen was not inhibited by FTY720 treatment in vivo. Serum and spleen samples were collected at day 5 after immunization with NP-Ficoll from control (▪) or FTY720-treated (□) mice. (A) Serum NP-specific IgM antibodies were determined by ELISA. (B) Splenic NP-specific, IgM-producing AFCs were enumerated by ELISPOT. Data (mean ± SE) were from an experiment with 4 individual mice in each group.