Immune synapse formation determines interaction forces between T cells and antigen-presenting cells measured by atomic force microscopy

Abstract

During adaptive immune responses, T lymphocytes recognize antigenic peptides presented by MHC molecules on antigen-presenting cells (APCs). This recognition results in the formation of a so-called immune synapse (IS) at the T-cell/APC interface, which is crucial for T-cell activation. The molecular composition of the IS has been extensively studied, but little is known about the biophysics and interaction forces between T cells and APCs. Here, we report the measurement of interaction forces between T cells and APCs employing atomic force microscopy (AFM). For these investigations, specific T cells were selected that recognize an antigenic peptide presented by MHC-class II molecules on APCs. Dynamic analysis of T-cell/APC interaction by AFM revealed that in the presence of antigen interaction forces increased from 1 to 2 nN at early time-points to a maximum of ≈14 nN after 30 min and decreased again after 60 min. These data correlate with the kinetics of synapse formation that also reached a maximum after 30 min, as determined by high-throughput multispectral imaging flow cytometry. Because the integrin lymphocyte function antigen-1 (LFA-1) and its counterpart intercellular adhesion molecule-1 (ICAM-1) are prominent members of a mature IS, the effect of a small molecular inhibitor for LFA-1, BIRT377, was investigated. BIRT377 almost completely abolish the interaction forces, emphasizing the importance of LFA-1/ICAM-1-interactions for firm T-cell/APC adhesion. In conclusion, using biophysical measurements, this study provides precise values for the interaction forces between T cells and APCs and demonstrates that these forces develop over time and are highest when synapse formation is maximal

2B4 Engagement Mediates Rapid LFA-1 and Actin-Dependent NK Cell Adhesion to Tumor Cells as Measured by Single Cell Force Spectroscopy

“…Recently, the peptide-specific interaction forces between CD4 + T helper cells and APCs were determined by SCFS (26). In this study the initial interaction forces were ∼1 nN, which matches very well with our findings.…”

“…NK cells may therefore be much faster than T cells in establishing cellular adhesion, which is in line with their quick responses during innate immune reactions and that has been suggested to be essential for their effective cytotoxic activity (27). In T cells maximal adhesion forces of ∼14 nN were measured after 30 min contact time (26). In our experimental setup it was not possible to make accurate measurements after such long contact times, possibly because NK cells can already kill their target cells within this time frame.…”

Quantification of Cell Adhesion Force with Atomic Force Microscope

“…At present, the traditional single cell force spectroscopy is difficult to test the cell maximum adhesion with long contact time, even if Hosseini et al succeeded to prove the relationship between cell adhesion and time, but in the case of longer contact time, it is easy to test failed [9]. The reason is that the adhesion between cells and the substrate exceeds the chemical adhesion of cells to the cantilever.…”

Redox Remodeling by Dendritic Cells Protects Antigen-Specific T Cells against Oxidative Stress

“…3A, 3B), thus implying that transmembrane exchange of cystine/cysteine is not a major mechanism accounting for thiol induction in Ag-specific T cells. Interaction between ICAM-1/ LFA-1 was shown to be important for firm DC/T cell adhesion (25). Treatment of DCs with Abs against ICAM-1, before and during coculture with T cells, significantly reduced the induction of cs-and ic-thiol in Ag-specific T cells (Supplemental Fig.…”