The opposing forces of shear flow and sphingosine-1-phosphate control marginal zone B cell shuttling.

ABSTRACT: Splenic marginal zone B cells (MZB) shuttle between the blood-filled marginal zone for antigen collection and the follicle for antigen delivery. However, it is unclear how MZBs migrate directionally from the marginal zone to the follicle. Here, we show that murine MZBs migrate up shear flow via the LFA-1 (?L?2) integrin ligand ICAM-1, but adhere or migrate down the flow via the VLA-4 integrin (?4?1) ligand VCAM-1. MZBs lacking Arhgef6 (Pak-interacting exchange factor (?PIX)) or functional LFA-1 are impaired in shuttling due to mislocalization toward the VCAM-1-rich red pulp. Sphingosine-1-phosphate (S1P) signaling through the S1PR3 receptor inhibits MZB migration up the flow, and deletion of S1pr3 in Arhgef6 -/- mice rescues mislocalized MZBs. These findings establish shear flow as a directional cue for MZB migration to the follicle, and define S1PR3 and VCAM-1 as counteracting forces that inhibit this migration.

SUBMITTER: Tedford K 

PROVIDER: S-EPMC5741619 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature