In vivo function of the lipid raft protein Flotillin 1 during CD8+ T cell-mediated host surveillance

Flotillin-1 (Flot1) is a highly conserved, ubiquitously expressed lipid raft-associated scaffolding protein. Migration of Flot1-deficient neutrophils is impaired due to a decrease in myosin II-mediated contractility. Flot1 also accumulates in the uropod of polarized T cells, suggesting an analogous role in T cell migration. Here, we analyzed morphology and migration of naive and memory WT and Flot1-/- CD8+ T cells in lymphoid and non-lymphoid tissues with intravital two-photon microscopy, as well as their clonal expansion during antiviral immune responses. Flot1-/- CD8+ T cells displayed minor alterations in cell shape and motility parameters in vivo but showed comparable homing to lymphoid organs and infiltration into non-lymphoid tissues. Taken together, Flot1 plays a detectable but unexpectedly minor role for CD8+ T cell behavior under physiological conditions.