Annexin A6 regulates interleukin‐2‐mediated T‐cell proliferation

Annexin A6 (AnxA6) has been implicated in cell signalling by contributing to the organisation of the plasma membrane. Here we examined whether AnxA6 regulates signalling and proliferation in T cells. We used a contact hypersensitivity model to immune challenge wild‐type (WT) and AnxA6 −/− mice and found that the in vivo proliferation of CD4 + T cells, but not CD8 + T cells, was impaired in AnxA6 −/− relative to WT mice. However, T‐cell migration and signalling through the T‐cell receptor ex vivo was similar between T cells isolated from AnxA6 −/− and WT mice. In contrast, interleukin‐2 (IL‐2) signalling was reduced in AnxA6 −/− compared with WT T cells. Further, AnxA6‐deficient T cells had reduced membrane order and cholesterol levels. Taken together, our data suggest that AnxA6 regulates IL‐2 homeostasis and sensitivity in T cells by sustaining a lipid raft‐like membrane environment.