title: Transient T cell accumulation in lymph nodes and sustained lymphopenia in mice treated with FTY720.
abstract: FTY720 (2-amino-2-[2-(4-octylphenyl)ethyl]propane-1,3-diol hydrochloride) is an orally available immunomodulatory agent that induces severe peripheral blood lymphopenia. Most studies of these lymphopenic effects have been limited to short-term exposure to FTY720. FTY720 alters the ability of lymphocytes to respond to sphingosine-1-phosphate (S1P) through S1P receptors, particularly S1P1. FTY720 affects different leukocyte populations and their trafficking through major lymphoid organs. We show the dynamics of CD4 T, CD8 T, and B lymphocyte recirculation in all major lymphoid compartments during 21-day FTY720 treatment of normal C57BL/6 mice. Following a transient increase in peripheral lymph nodes and Peyer's patches, lymphocyte recirculation reaches a new steady state. Other lymphoid organs show transient changes in lymphocyte composition with various patterns. At 21 days of FTY720 treatment, total body lymphocyte content is reduced by 20% and blood lymphocytes by 80%. Modeling suggests that the new steady state is due to a combination of reduced naive lymphocyte release from the thymus and a transient reduction of lymphocyte egress from lymph nodes. Our data indicate that the commonly held belief that FTY720 blocks lymphocyte egress from lymph nodes cannot fully explain the lymphocyte dynamics observed with prolonged treatment.
authors.affiliation: Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Morris
authors.forename: David R
authors.initials: DR
authors.lastname: Gibb
authors.forename: Franck
authors.initials: F
authors.lastname: Picard
authors.forename: Volker
authors.initials: V
authors.lastname: Brinkmann
authors.forename: Marty
authors.initials: M
authors.lastname: Straume
authors.forename: Klaus
authors.initials: K
authors.lastname: Ley
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects* / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D000068876:Fingolimod Hydrochloride; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008198:Lymph Nodes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D008221:Lymphoid Tissue / Q000166:cytology / Q000187:drug effects; D008231:Lymphopenia / Q000139:chemically induced* / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D011409:Propylene Glycols / Q000494:pharmacology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects*
chemical_list: D007166:Immunosuppressive Agents; D011409:Propylene Glycols; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine