Mike Barnkob:Protocols/Visualization/Immunofluorescence on cell lines
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Immunofluorescence protocol
This is a protocol for doing IF (immunofluorescence) on adherent and non-adherent cell lines.
This protocol was last updated on 27th of May 2015.
This protocol is not yet complete.
Reagents
- Coverslips: round Ø 13 mm for adherent cells (VWR, cat. 631-0141) or 24x60 mm for non-adherent cells (VWR, cat. 631-0150).
- Microscopy slides (VRW, cat. 631-0909).
- Antibodies and secondaries
- PBS
- Formaldehyde, 16%
- Trypsin or EDTA
Prepare:
- Fixative(s):
- 1 ml 4% formaldehyde.
- 250 ul 16% formaldehyde in 750 ul PBS.
- Ice-cold 100% methanol, 100% ethanol or 1:1 mix of ethanol/methanol.
- Keep at -20°C before use.
- 1 ml 4% formaldehyde.
- Blocking solution: 1% bovine serum albumin (BSA) in PBS.
- 1g BSA to 100mL of PBS.
- BSA is in common reagents fridge.
- Blocking + permabilization solution: Blocking solution + 0.1% Triton X-100.
- 50mL of blocking solution + 50μL Triton X-100.
- Ice cold PBS: keep PBS at 4°C for washing steps.
Setup and controls
- Negative control: one samples prepared as others, but without antibody staining.
- Isotype control: one samples prepared as other, but has been stained with an irrelevant antibody of the same isotype which has no specificity to the protein of interest.
- Secondary control: : one samples prepared as other, but stained only with the secondary antibody.
Protocol for adherent cells
General notes
For staining cell surface proteins:
- Consider using 1mM EDTA instead of Trypsin for loosening cells, as Trypsin might strip receptors from the cell surface.
- The addition of sodium azide can be considered, to stop internalization of receptors; but this is also toxic to cells.
- Another approach for stopping internalization of receptors is to keep the cells on ice at all times and do spins at 4°C.
- Permabilization with Triton X-100 should be tried with care since it can destroys membranes and thereby also the membrane-associated antigens.
Coat glass slide
- Place cover slips in 24 well plate.
- Rinse cover slips with PBS and remove. Repeat 2 times. Wait 5 minutes between rinses.
- (Sterilize cover slips by leaving under tissue culture hood UV light for 15 min.)
- Plate out cells on coverslip and incubate them at 37°C for 24 hours.
Note: Use 400-500μL of cells with cell media in each well.
Fixation
Two methods:
- Incubating cells in 100% acetone (chilled to -20°C) for 5 min at room temperature, or:
- Incubate cells in 4% paraformaldehyde in PBS for 10 min at room temperature.
- Following either method, wash cells with ice-cold PBS x 3. Aspirate or decant off liquid.
Blocking, permeabilization and staining
Acetone fixed samples might not need permeabilization, and so a pure blocking solution can be tried.
- Incubate cells in blocking solution either with or without permabilization reagent (Triton X-100) for 20 min at room temperature.
- Incubate cells with 1st antibody, diluted in blocking solution for 1 hour at room temperature.
Note: Many protocols recommend incubating over-night at 4°C.
Note: If staining for intra-cellular antigen, consider using permabilization solution instead. - Wash cells with PBS x 3. Aspirate or decant off liquid.
Incubate with antibodies
Counter-stain
Mount
Protocol for non-adherent cells
Reference
- "Fluorescent Staining of Cell Surface Antigens on Viable Cells Using Indirect Immunofluorescence", Rodgers L, 2006, CSH Protocols
- "How To Fix Adherent Cells For Microscopy And Imaging", Redig J, 2013
- "Immunofluorescence labeling of cell surface antigens in Dictyostelium", Vernay A and Cosson P, BMC Research Note, 2013
- Abcam's immunofluorescence (IF) protocol