The overall goal of this imaging protocol is to visualize multiple proteins in an activated T cell, using single molecule localisation microscopy. This method can help answer key questions in the T cell activation field such as, the single molecule distribution of TC or microcluster components. The main advantage of this technique is that, it allows greater multiplexing than achieved by current supervised solution microscopy methods.
To begin, directly conjugate antibodies with Alexa 647 dye, using the Alexa 647 antibody labeling kit, following the labeling protocol provided by the manufacturer. Centrifuge the labeled antibodies for five minutes at 20, 800 times G.Following centrifugation, collect the supernatant to remove the aggregated antibodies. Next, coat A12 cover slip chambers with 250 microliters of 01%poly-l-lyzine for 15 minutes.
Then, aspirate the solution without rinsing and dry the chambers at 65 degree celsius for 30 minutes. Prepare dilution of 100 nanometer fluorescent nanodiamonds or FNDs, in one PBS, test various dilutions to ensure that enough FNDs will be visible in each field. Vortex the diluted FNDs for one minute.
Next, sonicate the FND supernatant for 30 seconds at a high power setting. Incubate the sonicated FND supernatant in a poly-l-lyzine coated A12 cover slip chamber for 30 minutes at room temperature. After washing the chamber five times, with 1x PBS, visualize the FND coated chamber using 647 nanometer laser excitation on the turf microscope.
Use a 100x objective tealed a 61 by 61 micron field of view. Ideally, four to 10 individual FNDs should be visible in the field of view, given the appropriate dilution of FNDs, with at least one FND present in each quadrant of the imaging field. Once the proper density of FNDs has been achieved, add 250 microliters of anti-CD3 antibody to each well.
Incubate the chamber for one hour at 37 degree celsius or overnight at four degree celsius. Following incubation, remove the solution from the wells and add 1x PBS for 30 seconds. Repeat this wash step five times.
Spin one milliliter of Jurkat T cells at 800 times G for six minutes. Jurkat T cells should ideally be at a concentration of 0.5 to one million cells per milliliter concentration before spinning. Re-suspend the cells in 300 microliters of 1x HBS solution.
Meanwhile, add 150 microliters of 1x HBS solution to each well of the chamber and incubate at 37 degree celsius for 15 minutes. Then, add 50 microliters of the re-suspended Jurkat T cells to each well and incubate for three minutes at 37 degree celsius. Next, add 300 microliters of 4%paraformaldehyde to each well and incubate for 30 minutes at 37 degree celsius.
After washing three times with 1x PBS, permeabilise the cells, by adding 250 microliters of 01%Triton x solution for five minutes at room temperature. Following three additional washes with 1x PBS, add 250 microliters of 1%fish gelatin solution to each well for 30 minutes at room temperature. Finally, wash the cells three more times with 1x PBS.
Add 200 microliters of labeled antibody at 0.1 to 0.5 micrograms per milliliter to the fixed cells for one hour at room temperature. After washing the cells five times with 1x PBS, add one milliliter of STORM buffer and cover the chamber with a glass cover slip to limit exposure. Use clamps on the microscope stage to hold the cover slip chamber in position.
This step is critical for large scale multiplexing, since the same field of view must be present after several rounds of washing and incubation. Using a low 647 nanometer laser power in turf mode, locate a stained cell with at least three FNDs in the field of view. Increase the 647 nanometer laser power and acquire the images.
Typical parameters can be found in the text protocol. Wash the cells five times with 1x tris-buffered saline or 1x TBS. Then, add one milliliter of elution buffer and incubate at room temperature for one minute.
Repeat the elution three times. Use the exact elution conditions and a number of elution rinses needed to remove the signal as specified for each antibody. Then, wash the cells three times with 1x TBS and add one milliliter of 1x PBS.
Proper execution of this elution step, will result in removal of previously bound antibody and allow higher efficiency for subsequent antibody labeling. It is important to use TBS for washes to minimize precipitation between elution steps. Photo bleach the cells using a 647 nanometer laser at high power, with a 405 nanometer laser at two to five milliwatts to photo activate Alexa 647 dyes in the dark state.
Wait until all remaining signal from non-eluted antibody is photo bleached. Typically, this takes two to five seconds of laser exposure. Acquire sample images, using the STORM settings after illusion and photo bleaching, to confirm removal of the signal.
Next, add 250 microliters of 4%paraformaldehyde for 15 minutes. This prevents reverse cross-linking of fixed molecules in the cell. Wash the cells three times with 1x PBS.
Repeat these steps for sequential labeling of multiple targets. Finally, perform drift correction and alignment of multiplex image stacks at described in the text protocol. The sequential illusion and standing method was used to produce the multiplex MET STORM image of microclusters and other structures in an activated Jurkat T cell.
The final MET STORM image has been corrected for a drift and alignment, using average fiducial correction and FND fiducial markers. Shown here, are single molecule localisation microscopy images of a single FND localized in 30, 000 image frames before and after drift correction with average fiducial correction. Similarly, here are single molecule localisation microscopy images of an activated Jurkat T cell stained with anti-phosphorelated SLP76 antibody and FND futusial markers, before and after drift correction with average futusial correction.
After watching this video, you should have a good understanding of how to perform multiplexed super resolution imaging of proteins in an activated T cell, using MET STORM. Once mastered, this technique can be done in three hours for each multiplexing round. While attempting this procedure, it's important to remember to keep the specimen in the same position on the microscope stage.
This can be done using stage clamps. Don't forget that working with our modified STORM buffer, can be extremely hazardous and precautions such as, respirators and goggles should always be taken while performing this procedure.
