Boolean Gating


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. 

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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.


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 tailoring gates per population

When tailoring a gate per population (TPP), new populations will be generated using the AND Boolean operator. TPP is a great option if it is necessary to set the location or size of a gate depending on a certain parent population. When a gate is tailored per population, it appears in the same place on all files but appears in a different place depending on the parent population. It is also a useful tool to batch apply a gate to multiple parent populations easily. 

When a population is created as a result of TPP, its expression cannot be altered in any way. This appears as the expression in the Boolean expressions tab being in lighter colors and not clickable.


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.


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