| Popis: |
T cells are one of the most pivotal cell types in the human adaptive immune system. They have the capacity to eradicate primary, metastatic, relapsed tumours and can ameliorate otherwise fatal viral infections. Not surprisingly therefore, the activation and expansion of T cells has become one of the main focuses for immunotherapy and immune gene therapy. However one of the problems of T cell mediated immunotherapy in terms of delivering significant clinical impact to patients, is the expansion of high numbers of functional antigen specific effector T cells. The current approaches for expanding T cells have a number of drawbacks in terms of timing, reproducibility and reliability. Many if not all the currently available systems rely on ex vivo cell manipulation, which concordantly leads to short T cell survival in vivo after infusion. In vivo artificial expansion systems would clearly circumvent this problem. Nevertheless active immunotherapy is not always the solution since sometimes in some patients, the T cells that could be potentially in- vivo expanded no longer exist because they have been deleted, killed or anergised. Therefore a flexible system should be constructed in order to performed both adoptive and/or active immunotherapy depending on the patients requirements. Currently there is no comprehensive artificial Antigen Presenting Cell system (aAPC) for both effective ex vivo and in vivo antigen specific T cell expansion. Therefore in order to address this we have constructed a novel artificial nano-sized super para magnetic antigen presenting cell system (aAPC) capable of priming and expanding antigen specific T cells ex vivo and in vivo. As defined by the NIH, nanotechnology uses nanoscale injectable, targeted and traceable devices capable of important immunological/clinical functions. This nano-system was constructed using the latest generation of immuno liposomes, approved for in vivo human use since they are non-toxic, biodegradable, avoid rapid recognition by the reticulo endothelial system, are safe in terms of size being 50 times smaller than average cells at lOOnm, have good stability and favourable pharmacokinetic behaviour for effective in vivo trafficking. We have coated these liposomes with an optimised number of MHC Class I / peptide complexes and a specific selected range of adhesion (anti LFA-1), early activation (anti CD28 and anti CD27), late activation (4-IBB) and survival receptors (anti CD40L) in the form of Fab antibody regions or monoclonal antibodies. We have made these immuno liposomes traceable since they carry fluorescent lipids and iron oxide super para magnetic nano particles or spios of 13nm size, which make them traceable in vivo using fluorescence and/or by Magnetic Resonance Imaging (MRI). The super para magnetic liposomes are also able to facilitate their own focusing to specific organs, tumour sites or body areas by applying external magnetic attraction. Production of this nano immune liposome system in a ready to use form is achievable in less than 48 hrs and viable for at least 7 days. After ex vivo stimulation with this artificial nano system using CMV pp65 as a model antigen, we have established successful expansions with high T cell numbers (55 to 200 fold) in CMV positive individuals, which are superior when compared with other systems such as peptide pulsed DCs, which are one of the standard methods currently used, coated Daudi cells, magnetic commercial beads and modified tetramers. The T cells are fully functional in terms of degranulation and production of cytokines when specifically challenged. They express predominantly effector-memory and memory phenotypes. We have demonstrated by double fluorescent staining that these liposomes activate T cells directly in an antigen specific fashion and also semi-directly by being incorporated on the surface of the natural APCs in a similar manner as exosomes. When tested in naive individuals, this nano system was also capable of accomplishing initial low levels of T cell priming without help of any adjuvants. In conclusion, we have generated an efficient artificial APC, which embodies a powerful, controllable and superior approach with enormous potential for cancer nanotechnology and T cell immunotherapy for use either in vivo or in vitro. |
