What is required to determine PMT sensitivity during cytometer calibration?

To determine PhotoMultiplier Tube (PMT) sensitivity during cytometer calibration, it is essential to use a combination of single and multipeak beads. Single peak beads provide clear, defined signals that help establish the baseline sensitivity of the PMT for detecting fluorochrome intensity. These beads allow for the assessment of the detector's response to low fluorescence levels, ensuring that the instrument can accurately detect minimal signals.

On the other hand, multipeak beads are used to check the linearity and dynamic range of the PMT across a wider spectrum of fluorescence intensities. By examining how the system responds to beads with multiple peaks, one can assess whether the PMT maintains consistent responsiveness across varying levels of fluorescence. This combination is crucial for calibrating the photodetector to ensure it can accurately capture and quantify fluorescence in a range of experimental conditions, thereby providing reliable data for cytometric analysis.

Using only single peak beads or only unstained beads would not provide the necessary range of responses to fully assess PMT sensitivity, while monoclonal antibodies are not typically used for this specific calibration purpose. Instead, their role usually lies in targeting specific antigens, which is distinct from the technical calibration of the cytometry system.