Methods and materials for specific imaging of active enzyme in a live or intact cell are disclosed. The enzyme of interest tagged to reporter protein (donor) is exogenously expressed in a cell. The conversion of proenzyme to active enzyme (containing reporter protein) is achieved upon applying an appropriate stimulus to the target cells. The activated enzyme is labelled with an activity-based probe carrying a fluorophore (acceptor). The covalent labelling of active enzyme by the activity-based probe creates a FRET pair which provides the opportunity to exquisitely image the function of an “active enzyme”. This method is used for specific imaging of the function of active caspase-3,-7,-8,-9 and cathepsin-B and also for profiling of inhibitors of caspases and cathepsin B.

The present disclosure provides for conversion-resistant CAR regulatory T cells (Tregs) and bi-specific antibodies, and methods to use these Tregs and antibodies for the treatment of autoimmune diseases and for prevention of organ transplant rejection.

Methods and materials for specific imaging of active enzyme in a live or intact cell are disclosed. The enzyme of interest tagged to reporter protein (donor) is exogenously expressed in a cell. The conversion of proenzyme to active enzyme (containing reporter protein) is achieved upon applying an appropriate stimulus to the target cells. The activated enzyme is labelled with an activity-based probe carrying a fluorophore (acceptor). The covalent labelling of active enzyme by the activity-based probe creates a FRET pair which provides the opportunity to exquisitely image the function of an active enzyme. This method is used for specific imaging of the function of active caspase-3,-7,-8,-9 and cathepsin-B and also for profiling of inhibitors of caspases and cathepsin B.

The invention described herein features infrared fluorescent protease reporters (iProteases) and methods of use thereof. The iProteases can be used in in vivo and in vitro assays to detect protease activity and disease states associated with protease activity. In a still further embodiment, the present invention provides a kit comprising any of the above described polynucleotides. In a further aspect, the present invention provides a method of in vivo optical imaging. In a still further embodiment, the in vivo imaging is performed in a living animal. In a further aspect, the present invention provides a method of detecting protease activity, the method comprising expressing a polypeptide according to any of those described above in a cell.

The invention described herein features infrared fluorescent protease reporters (iProteases) and methods of use thereof. The iProteases can be used in in vivo and in vitro assays to detect protease activity and disease states associated with protease activity. In a still further embodiment, the present invention provides a kit comprising any of the above described polynucleotides. In a further aspect, the present invention provides a method of in vivo optical imaging. In a still further embodiment, the in vivo imaging is performed in a living animal. In a further aspect, the present invention provides a method of detecting protease activity, the method comprising expressing a polypeptide according to any of those described above in a cell.