Cellular contacts are crucial in determining function, yet these complex interactions are difficult to delineate due to their dynamic nature. This complexity is evident in the antigen-specific interactions between antigen-presenting cells (APCs, such as dendritic cells, B-cells or macrophages), and CD4+ T-cells. Recognition of cognate antigen by T-cells results in a rapid initiation of an intracellular signalling cascade, leading to translocation of specific transcription factors to the nucleus of the cell: factors that are important in determining the functional outcome of T-cell activation. These early interactions between T-cell and APC can determine the fate of a CD4+ T-cell. Factors such as quality, quantity, duration and strength of interaction between a T-cell and APC, can influence whether an effective immune response is initiated (and which type of response) or if a state of anergy is induced. Therefore understanding more about these factors that control this decision would help in the development of therapeutics that aim to initiate protective immunity or to improve selective suppression in autoimmunity and restore immune anergy. Within this thesis a novel approach is presented to dissect this interaction using optical tweezers. A novel optical tweezer setup is developed, providing greater control over cells and enhancing cell viability. This system is used to demonstrate quantification of the interactions between individual T cell and APC pairs, whereby the force of interaction increased from 3.3 (± 1.4) Piconewton (pN) in steady-state to 8.5 (± 5.7) pN upon antigen recognition. Importantly, the applicability of optical tweezers in addressing important biological questions was tested, investigating how T cell/APC interactions were altered during L-arginine deprivation, upon recognition of citrullinated antigen or in cells lacking an important signalling molecule.The approach presented here provides a novel tool for further understanding cell-cell interactions as well as demonstrating the potential for wide-ranging pharmaceutical screening applications.
|Date of Award||23 Mar 2015|
- University Of Strathclyde
|Sponsors||EPSRC (Engineering and Physical Sciences Research Council)|
|Supervisor||Owain Millington (Supervisor) & Trevor Bushell (Supervisor)|