Flow Cytometry
How a Flow Cytometer Works: A Look Inside the Magic Box
A flow cytometer is a device used to illuminate objects and capture and quantitate light emitting from these objects. The “objects” are normally single cells dispersed in a medium, but could very well be polystyrene beads, cell fragments or debris, or even large molecules. So, What’s in the Box? Using your highly tuned powers of deduction, you…
Read MoreSpot the Difference: 5 Ways to Improve the Presentation of Your Flow Cytometry Data
Take a look at the dotplot below, are you happy with the way it’s presented? Do you think that you could recreate that experiment? If you were a reviewer, would you accept that figure? Sure, it’s flow plot, it shows 3 populations of which two are gated. Read many journals and you will see data…
Read MoreThe Exciting (and Emitting) World of Fluorescence
Flow cytometry is a fluorescence-based technology, as is fluorescence microscopy and confocal microscopy. Fluorescence is fundamental to how a cytometer gathers data, but I am often surprised, as a core manager, at how little new users know about the process of fluorescence. So, this is where I always start the training process. Let’s get physical…
Read MoreSorting Large Cells and Materials by Flow Cytometry
Flow cytometers and cell sorters were designed with blood cells in mind. This means that commercial cell sorters are optimized for sorting cells typically smaller than about 20 µm in diameter. However, it turns out that many cell types, including those of mammals, are larger than 20 µm. So what are your options if you…
Read MoreCatching Greatness: Measuring Cellular Degranulation
One of the key characteristics of cytotoxic cells (i.e. CD8+ T cells, natural killer cells) is the presence of pre-formed cytoplasmic lysosomal granules. These structures house perforin and granzyme; two molecules that are essential for the lysis of target cells. Upon effector cell activation, granules are polarized toward the target cell and the contents are…
Read MoreAn Introduction to Spectral Overlap and Compensation Protocols in Flow Cytometry
It strikes fear into the hearts of new cytometrists. Compensation. More fights have started over the proper way to compensate at meetings than anything else. This article will strive to shed some light on the principles of compensation, and equip you with the tools necessary to achieve compensation mastery for your research experiments. Compensation is…
Read More5 Ways to Improve Your Fluorescent Protein Sorting
If, like many people, you use fluorescent proteins to view your transfection efficiency or your CRISPR gene editing, you can also isolate cells with different expression levels of fluorescent proteins. Here are 5 ways to improve your sorting experiment.
Read MoreA Simple Way to Measure T cell Killing Activity In Vivo
Have you ever wondered what a cell’s life is like? Do they constantly communicate to each other or do they just go on their own daily business? There is an easier way and it involves super advanced molecular “crayon” technology.
Read MoreGateway to the Cellular Kingdom: Cell Fixation and Permeabilization Techniques
One of the much sought after question asked by many researchers worldwide is – “What is the gene expression profile of a single cell within a heterogenous pool of cells?” While mass cytometry is the current ‘hot’ methodology for single cell analysis, the good old flow cytometry can help us perform rapid analysis of single…
Read MoreLocating Your Cellular Apoptosis Squad: Annexin V Staining Assays
In real life, cells are instructed to commit suicide for the greater good of the organism. The programmed cell death (apoptosis) is important during development of a multi-cellular organism. A good example you will appreciate is the dis-appreance of the tail from a tadpole as it turns into a frog. On the reverse, the lack…
Read MoreMIFlowCyt Guidelines: Helping You to Publish Your Flow Data
Wow, you’ve done it! Your experiment worked and your boss asked you to write it up for publication in your favorite journal. Where to start with presenting your flow data? Take a deep breath, help is in hand in the form of the MIFloCyt Guidelines. As with other scientific techniques, there are ‘Minimum Information about…
Read MoreTroubleshooting: No Events on Your Cytometer
It’s happened to us all, you are ready to run your samples on the cytometer and you can’t see your cells on the screen. Here are a few tricks to troubleshooting this: Cytometer vs. computer connection The different types of cytometers will need different orders for switching on the cytometer and computer. Some are cytometer…
Read MoreThe Nope-Nope-Nevers of Using a Flow Cytometer
There are some wonderful toys in the lab that enable us to open up a whole new world in science. One of those is a rather pricey and an incredibly sensitive laser-based apparatus capable of counting and sorting cells, detecting biomarkers, and engineering proteins: the flow cytometer. By propelling cells through the path of the…
Read MoreHerzenberg and the Invention of the FACS Machine
The flow cytometer that we have all grown to know and love may have only come into its own in the 1990’s, but who would have known that the first cell sorter was invented as early as the 1950’s? With the recent death of one of the key developers of fluorescence activated cell sorting (FACS),…
Read MoreBeing “Accuri-te” Through Cytometry: A Guide to Accuri C6 Software
A new lab toy to make it big in the last 5–10 years is the Accuri C6 cytometer (now under the BD umbrella), a low-cost instrument in comparison to the big boys. Lightweight, with a small footprint and straightforward maintenance, it’s often the cytometer of choice. It may be suitable for those labs that require…
Read MorePutting Down a Marker in Flow Cytometry to Help Determine Positivity
In many biological experiments the question that a researcher wants to ask is – ‘do some or all of my cells express a particular protein?’ There are many ways of doing this, which you will be familiar with e.g. Western blotting, immunoprecipitation, microscopic examination of stained cells and even mass spectrometry. Using Flow Cytometry to…
Read MoreSetting Voltages for Optimal Sensitivity
After panel design, and titration of the reagents, the next most important step in flow cytometry is setting the proper voltages on the photomultipler tubes (PMTs). These detectors take the photons of light emitted by the fluorochromes on the cells and convert them to electrons, which ultimately become the voltage current that is digitized and…
Read MoreA Guide to Flow Cytometry Software: Becton Dickinson’s ‘Diva’
If you use a Becton Dickinson (BD) cytometer in your lab, the chances are you are acquiring your data using ‘Diva’ software. Diva software is used to acquire your cytometry data on LSRII, LSRFortessa, CantoII and Aria cell sorters. As well as acquiring your data using Diva software, you can also analyse your data after…
Read MoreFlowJo Software: how’s your FlowJo mojo?
Generally, once you’ve acquired your samples on a cytometer, the hard (but hopefully fun!) part of making sense of all the data begins. This can be increasingly complex depending on the number of cells, populations, parameters, and combinations. So where we use the dedicated software aligned to the analyser for acquisition, we frequently use alternative…
Read MoreBasic Statistics for Flow Cytometrists – Part 1
Part of my job in running a core flow cytometry facility is to make sure that the experiments that my users run have been optimised. But that optimisation can be split up into several areas. The first area is experimental planning: What do you want to know? Can you do this by flow cytometry? And…
Read More10 Hints For Setting Up A Core Flow Cytometry Lab
If you are establishing a flow core facility or even setting up just one cytometer, then you need to know a few things before you plan your new lab and start looking at purchasing cytometers: Before You Start 1. Know Your Customer It’s really important to know if you are going to be setting up and…
Read MoreData Spread and How to Measure It: the Coefficient of Variation (CV)
No matter how we make measurements, there will be variation (a spread of data). Take 100 people and ask them to guess your age and you will get a range of results: some will be too low (excellent!), some too high (not so good!). It is the same with any of our laboratory experiments –…
Read MoreShapiro’s Laws of Flow Cytometry
Once you have been in the field of Flow Cytometry for a bit, the name Howard Shapiro will be familiar to you. However, for those who are new to Cytometry, you might not be aware of Dr Shapiro and his fabulous book ‘Practical Flow Cytometry’. Most Cytometrists have a paper copy of this bible of Flow…
Read MoreImportance of Antibody Titration in Flow cytometry
After designing a multicolor flow cytometry panel and securing the necessary cells and reagents, the process of optimization of the panel can begin. The first step in that optimization is titration of your antibodies. In this process, following a standard protocol to be used in the final analysis, you stain a known amount of cells with…
Read MoreBeginners Guide to Designing Your Own Polychromatic Flow Panel
“The greater the power, the more dangerous the abuse.” – Edmund Burke “With great power comes great responsibility.” – Uncle Ben (quoting Voltaire) While it’s unlikely that either of these speakers performed multi-dimensional flow cytometry, it is important to remember these quotes in the context of developing and implementing a good polychromatic flow panel. More fluorochromes are…
Read MoreA Numbers Game: the ‘How’ and ‘Why’ of Counting Cells
“It is the weight, not numbers of experiments that is to be regarded.” Isaac Newton Read any flow cytometry protocol and somewhere near the beginning will state something to the effect of ‘Place 1 million cells into a tube.’ The question is, faced with that special sample for THE experiment, how do you count cells…
Read MoreViability Dyes for Flow Cytometry: It’s Not Just a Matter of Life and Death
As Morrissey once sang “in the midst of life we are in death, etc.” A fact of life in the research Lab is that whenever we run an assay there will almost certainly be some cell death in our sample. This may be insignificant in some techniques but in others it can be problematical. Why…
Read MoreAll sorted? Getting the best out of your cell sorting facility
If you are bringing cells to a core to be sorted there are a few things you can do to optimise your sorting and will help the core staff. Here are a few hints: 1) Know the size of your cells Do you know the size of your cells? Not many people do and its one of…
Read MoreImmunophenotyping: Identifying Who’s Who in the Cellular World
Figuring out what’s what When studying cells and cell subsets (and cell sub-subsets, and so on!!) we need ways to identify and classify every single cell. This will allow us to individually analyse each population and, for example, help to discover their role in health and disease. A principal way we do this is by looking…
Read MoreUsing Flow Cytometry for Fluorescence Resonance Energy Transfer
A marriage of sorts Fluorescence resonance energy transfer, or FRET, is often done using a microscope, which means it can be difficult to analyze large numbers of cells in one sitting. One way to overcome this, is by combining FRET with fluorescent-activated cell sorting (FACS), giving you a high-throughput method to screen for protein interactions…
Read MoreWhere Are My Cells: Part 2
The golden rule of flow cytometry, especially cell sorting is: ‘Put good cells in and get good cells out’. When you sort you might not get good cells out and you may not get the numbers you were expecting. In my previous article I touched on a few reasons why your cell numbers might be…
Read MoreUsing Flow Cytometry for Cell Proliferation Assays: Tips for Success
We all know, generally from bitter experience, that experiments don’t always work first time and that sometimes the little things that govern success are the things that get left out of that online protocol! So whether you are assessing proliferation by nucleotide incorporation or by dye dilution, here are some handy hints to help you…
Read MoreWhere Are My Cells: Part 1
If there are a million cells of interest in your sample and you pass them through a sorter, you might expect to get a million cells back. But you don’t – and here is why. Hardware aborts A hardware abort occurs when an instrument can’t process the information about an event because it is still…
Read MoreOne For You, One For Me… How a Cell Sorter Works
Cell sorters do not operate by magic, even it looks that way. It’s about the application of physics, electronics, fast computers and formation of droplets. Whether you bring your cells to a flow core to be sorted or you sort them yourself, it important to know how the cell sorter works. Cells can be sorted…
Read MoreCrap in, crap out: Flushing Out The Problems in Your Flow Cytometry Data
“What Have You Done To My Cells??!!!” This cry of pain from researchers, frequently aimed at core facility operators, is heard after receiving incomprehensible data for an invaluable tube of cells. Equally baffling to the trained user of flow cytometric instrumentation is when data emerges that is either unreliable or inconsistent with the known properties…
Read MoreAll for one and one for all – Fluorescence Minus One Controls
Ever done a multicolour flow cytometry experiment, run all your controls, done your compensation and then started to analyse your data and realised that you can’t work out where to put your gates? To err is human… When acquiring data on a cytometer, there can be measurement errors due to counting statistics, errors in processing…
Read MoreTake Control of Your World – Five Controls for Flow Cytometry
No, this is not a call for Geeks to take over the world – just a tiny part of it – the part that ensures success in all experiments or at least a good way to analyze them if they fail. There are all too many entry points for error and variability that can be…
Read MoreIntracellular Cytokine Staining: Letting It All Build Up Inside
Cytokines, those small proteins that modulate immune cell responses, once translated are normally secreted rapidly out of the cell. So, previously we could only check the levels of cytokines secreted in the supernatant, but we wouldn’t know which cell was producing which cytokine. But what if we had a way to keep the cytokines inside the cell? Then we…
Read MoreCell Proliferation Round 2 And Beyond: The Dye Dilution Method
Like the legendary fight between boxers Bowen and Burke in 1893, the cell cycle in some cells goes on and on..round 1, round 2, round 3, round 4…before the final bell is rung. Nucleotide analogs, like BrdU or EdU, are great for examining 1-2 cell cycle division(s). In many studies though, for example the proliferation…
Read MoreBiosafety in Flow Cytometry – To Be or Not to Be…
Biosafety is one of those things many scientists don’t take seriously. I would guess, that like politics, there are 40% who believe biosafety is ‘over-emphasized’ and 40% who swear by biosafety. 20% are undecided. Needless to say, I’m on the side of biosafety. And here’s why: “CDC announced today that approximately 75 Atlanta-based staff are…
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