T cell stiffness is enhanced upon formation of immunological synapse

Abstract

T cells are activated by cognate target cells via an intimate contact, termed immunological synapse (IS). Cellular mechanical properties, especially stiffness, are essential to regulate cell functions, T cell stiffness at a subcellular level at the IS still remains largely elusive. In this work, we established an atomic force microscopy (AFM)-based elasticity mapping method on whole T cells to obtain an overview of the stiffness with a resolution of ~ 60 nm. Using Jurkat T-cells and primary human CD4+ T cells, we show that in the T cells in contact with functionalized surfaces, the lamellipodia are stiffer than the cell body. Upon IS formation, T cell stiffness is substantially enhanced both at the lamellipodia and in cell body. Chelation of intracellular Ca2+ abolishes IS-induced stiffening at the lamellipodia but has no influence on cell body-stiffening, suggesting different regulatory mechanism of IS-induced stiffening between the lamellipodia and the cell body.

Cellular forces during early spreading of T lymphocytes on ultra-soft substrates

“…The order of magnitude of the cell Young modulus, when spread on our aCD3 gels, should then be taken as the average of the ones measured over the two “softer” gels (namely 2 and 20 kPa here), leading to a value ~ 100 Pa. On the stiffer gels that do not mimic per se any relevant APC (Bufi et al 2015), the situation of the spreading could be very different, similar to what we reported for the effect of relaxing any shape constraint (Sadoun et al 2021). Nevertheless, one has to note that the order of magnitude of the Young modulus stays very close to the one usually reported as it is here (~100Pa), far more than what has been reported to be measured using dynamic AFM modes (> 10kPa, (Jung et al 2021)) which strengthen our conclusion above.…”