Background
During the manual gating process, there are often circumstances where a Boolean operator could help identify certain populations. The Cytobank platform supports the Boolean operators AND, NOT, OR and provides you the option to use parentheses to combine multiple Boolean operators.
Use the links below to jump to the relevant section:
- The Boolean expressions tab
- AND operator
- NOT operator
- OR operator
- Use parentheses to combine multiple operations
- Smart addition on operator in Boolean expressions
The Boolean expressions tab
In the Gating Editor, you can find the Boolean expressions tab near the Population tree and Sunburst view tabs. It shows the existing populations as a list and their expressions. A population is defined by a combination of populations, Boolean operators and gates. Hovering the mouse over the population expression shows the underlying definition of that population. The populations are colored blue and gates are colored grey.
Population definitions can be edited by clicking on one of the expression’s blocks or on the + icon. The Expression Builder tool lists all possible options to modify or add Parentheses, Boolean Operators, Populations or Gates.
You can create new populations by clicking on the New population button and adding the definition in the Expression field.
When gating groups are enabled, multiple sub-tabs in the Boolean expressions tab will be created, each corresponding to a different gating group. The same approach for building new populations or modifying existing ones will apply, and only the populations and gates belonging to the gating group you are working with will be displayed.
Also, with gating groups enabled, the Boolean expression tab will include a new Group sync column, which reflects the sync settings selected for each population. You will not be able to remove any gating group from the sync tab, but you will be able to add from the already existing ones. To do so, click on the plus sign inside the Group sync column and select from the menu:
This will lead to three scenarios:
- If the population you wish to synchronize to a group does not exist in the destination group, the population will be copied into the destination group.
- If the population you wish to synchronize to a group already exists within that group, the platform will override the population's definition to match the definition of the population being synchronized.
- If the channels used to define the pop in the originating group are not present in the destination group, the population and gate will be copied, but the populations won't be synced and the group sync will only reflect originating group.
Recommendations for building Boolean expressions using populations vs gates
When creating new populations from the Boolean expressions tool it is recommended to combine populations with one another, or populations with one last gate. It is not recommended to use pure gates to build the Boolean expressions. Please see the difference between gates and populations for more details.
For example, when Population 1 is created using CD33-lymphocytes (population) AND CD20+ B cells (gate), it shows in the population tree as below. Each expression can contain up to 50 components.
Edit the Population name by clicking on the pencil icon.
Or select one or more populations in the Boolean expressions tab to add a prefix or suffix, copy, or delete the population(s).
AND operator
When creating a sequential gating strategy you will use the AND operator to combine a new gate with an existing population. For instance, if you completed the gate on CD3+ and then create a CD4+ gate under the CD3+ population, a new population will be generated using the AND operator.
(In this sequential gating strategy, the CD3+CD4+ T cells population was created by drawing a CD4+ gate under the CD3+ T cells population. The Boolean expression includes the AND operator automatically.)
You can also use the AND operator to identify events located within the overlap of two or more populations/gates. For example, we created two populations CD33+ pSTAT3+ and CD33+ pp38+:
The population pSTAT3+ AND pp38+ only includes the events that fall within the overlap of both populations:
The difference between AND Boolean operator and copying gates to population
While the AND operator allows you to create only one population at a time by working on its Boolean expression, the Cytobank platform also offers you the possibility to copy a gate into a different population. To do so, you can either drag and drop or select the copy to population icon that appears when hovering over a gate name, and select all the populations you would like to copy the gate to from the pop-up window; then click on apply. This is a useful tool to batch apply a gate to multiple parent populations easily. Please note that the sync settings of the resulting population will differ depending on if the target mother population was selected from the same gating groups or from a different one. For more information please visit relevant articles on our support site.
NOT operator
Use the NOT operator to exclude events belonging to a second population. For example, we created two populations CD33+ pSTAT3+ and CD33+ pp38+:
The population pSTAT3+ NOT pp38+ only includes the events that are pSTAT3+ and excludes all the events pp38+:
OR operator
Use the OR operator to identify events located in all populations. For example, we created two populations CD33+ pSTAT3+ and CD33+ pp38+:
The population pSTAT3+ OR pp38+ includes all events in the pSTAT3+ and pp38+ populations:
Use parentheses to combine multiple operations
You can use Parentheses to combine more than one type of Boolean operator in the Population expression.
Smart addition on operator in Boolean expressions
The Cytobank platform smartly handles the operators when creating new populations using the Boolean expression builder. This way you build your Boolean expressions quickly and easily. For instance, if you add just a population at the end of a Boolean expression, an AND operator will automatically be added to complete the expression, without raising any error messages.
The Boolean expression tab can also display the population hierarchy when editing Boolean expressions. To do so, toggle on the Hierarchy View option on the right side. As a result, you don't need to switch back to the Population tree tab to view the hierarchical location of your newly added population.
*For Research Use Only. Not for use in diagnostic procedures.