The White Precursor/Pathological Cell (WPC) channel is used when the WDF channel provides evidence of blasts or abnormal lymphocytes. It acts as a refinement channel specifically assessing whether cells are present in the region where blasts might be expected . If no abnormal population is detected in this region, blast signaling is removed. For gating, the WPC channel also uses cell size (FSC), which is visible in another plot.

An important difference between the WDF and WPC channels is the degree of lysis. In the WDF channel, leukocytes are permeabilized, leaving the cell structure largely intact. In contrast, in the WPC channel, the cytoplasm is largely removed, leaving mainly the nuclear structure for analysis. Consequently, the side scatter (SSC) in the WPC channel depends mainly on the structure and density of the nucleus, and much less on cytoplasmic complexity.

In the WPC channel, mainly nuclear DNA is stained (rather than cytoplasmic RNA as in the WDF channel). As a result, blasts will exhibit lower SFL intensity than more mature cells.