Final answer:
Abnormal cell populations are represented on a Sysmex scatterplot by distinct clusters or peaks that indicate differences in cell size, granularity, or fluorescence, which are tied to specific cell properties such as CD8 expression.
Step-by-step explanation:
Abnormal cell populations are often detected using flow cytometry, which involves the measurement of the properties of cells as they flow in a fluid stream through a beam of light. The Sysmex scatterplot is a graphical representation of flow cytometry data, where data are collected from forward-scatter and side-scatter detectors. In the scatterplot, forward scatter correlates with cell size and is displayed on the y-axis, while side scatter correlates with cellular complexity or granularity and is represented on the x-axis, which is scaled logarithmically to show fluorescence intensity. Abnormal populations, such as those with altered cell size or granularity due to disease or mutation, will form distinct clusters or peaks separate from the normal cell population. For instance, in a Sysmex scatterplot, a histogram with two peaks might indicate the presence of two different cell populations, with the peak on the right indicating cells that express CD8 due to bound antibody, identified by their higher fluorescence readings, in contrast with a peak on the left, representing non-fluorescent cells that lack CD8 expression.