T cell microvilli constitute immunological synaptosomes that carry messages to antigen-presenting cells.
Authors
Hye-Ran Kim ; YeVin Mun ; Kyung-Sik Lee ; Yoo-Jin Park ; Jeong-Su Park ; Jin-Hwa Park ; Bu-Nam Jeon ; Chang-Hyun Kim ; Youngsoo Jun ; Young-Min Hyun ; Minsoo Kim ; Sang-Myeong Lee ; Chul-Seung Park ; Sin-Hyeog Im ; Chang-Duk Jun
Microvilli on T cells have been proposed to survey surfaces of antigen-presenting cells (APC) or facilitate adhesion under flow; however, whether they serve essential functions during T cell activation remains unclear. Here we show that antigen-specific T cells deposit membrane particles derived from microvilli onto the surface of cognate antigen-bearing APCs. Microvilli carry T cell receptors (TCR) at all stages of T cell activation and are released as large TCR-enriched, T cell microvilli particles (TMP) in a process of trogocytosis. These microvilli exclusively contain protein arrestin-domain-containing protein 1, which is directly involved in membrane budding and, in combination with vacuolar protein-sorting-associated protein 4, transforms large TMPs into smaller, exosome-sized TMPs. Notably, TMPs from CD4+ T cells are enriched with LFA-2/CD2 and various cytokines involved in activating dendritic cells. Collectively, these results demonstrate that T cell microvilli constitute "immunological synaptosomes" that carry T cell messages to APCs.