Flow Cytometry Protocols and Staining Methods
Author: Mike Blundell | Reviewer: Chloe Fenton
Flow cytometry protocols are used to prepare, stain, and analyze cells to measure cell surface and intracellular markers. These workflows typically include cell preparation, antibody staining (direct or indirect), intracellular processing, and data acquisition. This page helps you understand and choose the right staining method and protocol for your experiment.
Flow Cytometry Workflow Overview
- Prepare single-cell suspensions.
- Stain cells using direct or indirect antibody methods.
- Fix and permeabilize cells if analyzing intracellular targets.
- Acquire and analyze data using a flow cytometer.
Which Flow Cytometry Staining Method Should You Use?
| Method | Best Used For | Key Advantage | Limitation |
|---|---|---|---|
| Direct staining | Surface markers | Fast and simple workflow | Lower signal intensity |
| Indirect staining | Low-abundance targets | Signal amplification | Additional incubation steps |
| Intracellular staining | Cytokines and internal proteins | Access to non-surface markers | Requires fixation and permeabilization |
Direct and Indirect Staining, Staining of Intracellular Antigens, Permeabilization, and Cell Preparation Protocols
Access expert protocol tips and practical solutions to achieve reliable results.
The flow cytometry protocols below provide detailed procedures for generating single-cell samples and for treating and staining cells prior to using a flow cytometer. Protocols are available for:
- Cell preparation
- Direct staining of cells, applicable where the fluorophore is directly linked to the primary antibody
- Indirect staining of cells, applicable when using unconjugated or biotin-conjugated monoclonal and polyclonal antibodies
- Intracellular staining methods for intracellular antigens and cytokines
- DNA staining for cell cycle analysis
To further support your experiments, this downloadable infographic covers:
- Five essential staining approaches
- Sample preparation best practices
- A troubleshooting quick reference guide
What Is Direct Staining in Flow Cytometry?
Direct Staining Flow Cytometry Protocols
This is one of the simplest and most common staining methods, where live or fixed cells are incubated with directly labeled antibodies against cell surface antigens.
What Is Indirect Staining in Flow Cytometry?
Indirect Staining Flow Cytometry Protocols
If there is not a directly labeled antibody available, or you wish to amplify your signal, you can do indirect staining. This is where you stain a cell with a primary antibody against the antigen of interest and visualize using a labeled secondary antibody which recognizes the primary.
What Is Intracellular Staining in Flow Cytometry?
Intracellular Staining Flow Cytometry Protocols
In order to detect an antigen not present on the cell surface, cells have to be fixed and permeabilized to disrupt the cell membrane and allow entry of the antibody. Antigens can then be directly or indirectly labeled. Various methods are optimal depending on the antigen and antibody used.
- Direct immunofluorescence staining of intracellular antigens: the Leucoperm method
- Direct immunofluorescence staining of whole blood for intracellular CD68: the Leucoperm method
- Direct immunofluorescence staining of intracellular cytokines in blood
- Direct immunofluorescence staining of intracellular antigens: the methanol plus Leucoperm method
- Direct immunofluorescence staining of intracellular antigens: the digitonin method
- Direct immunofluorescence staining of intracellular antigens: the paraformaldehyde/saponin method
- Direct immunofluorescence staining of intracellular antigens using antibodies labeled with StarBright Dyes
Frequently Asked Questions
What is a flow cytometry protocol?
A flow cytometry protocol is a step-by-step method used to prepare, stain, and analyze cells using fluorescently labeled antibodies.
What is the difference between direct and indirect staining?
Direct staining uses labeled primary antibodies, while indirect staining uses an unlabeled primary antibody followed by a labeled secondary antibody to amplify signal.
When should intracellular staining be used?
Intracellular staining is used when detecting proteins or cytokines located inside the cell, requiring fixation and permeabilization.
What are the main steps in flow cytometry?
The main steps include cell preparation, antibody staining, optional intracellular processing, and data acquisition.
Cell Cycle Staining Flow Cytometry Protocols
Measuring DNA content for cell cycle analysis requires fixation and permeabilization of the nuclear membrane. We have protocols for staining using DNA binding dyes with and without antibody staining and a protocol for BrdU staining.
- Propidium iodide staining of cells for cell cycle analysis in combination with direct immunofluorescence intracellular staining
- Propidium iodide staining of cells for cell cycle analysis
- BrdU staining of cells for cell cycle analysis
Cell Preparation Flow Cytometry Protocols
Below are protocols for harvesting cells from various sources to obtain healthy cells, essential for optimal staining and analysis.
Product-Specific Flow Cytometry Protocols
Specific protocols to use with our antibodies.
Cell Activation Protocols
General activation protocols using pharmacological reagents and antibodies. Ideal to determine immune competence, marker upregulation, cytokine release, and proliferation by flow cytometry.
Flow Cytometry Products
Flow Cytometry Resources
Flow Cytometry Basics Guide Download
Get your own copy to peruse at your leisure
Download our updated Flow Cytometry Basics Guide to have practical advice, best practice examples, and a basic overview of all the important flow cytometry principles in one handy location.
Resources
Bio-Rad is committed to helping you succeed in Flow Cytometry by sharing knowledge and best practices from our experts. Below are some extremely useful resources to enhance your journey of discovery and support your success.