Membrane proteins can be stained with antibody without fixing cells.
This protocol stains cells in suspension for FACS analysis.
1. Add 25-50 Ál diluted antibody (in PBS) to 5x105 cells (25 Ál).
2. Incubate on ice for 30 minutes.
3. Wash twice with PBS/1% BSA/0.02% NaN3.
4. Add 50 Ál of an appropriate FITC-labeled secondary antibody.
5. Incubate on ice for 30 minutes.
6. Wash twice with PBS/1% BSA/0.02% NaN3.
7. Resuspend the cells in 100 Ál PBS/1% BSA/0.02% NaN3 and
analyze on a fluorescence activated cell sorter (FACS).