Figure 4.

Four fluorescence images from two different samples (left column: sample 1 and right column: sample 2) with a green filter (1A and 2A) and with a red filter (1B and 2B). Sample 1 (left column) was incubated with both primary AB and the AF647‐labeled secondary AB. Sample 2 (right column) is a negative control and was incubated only with the AF647‐labeled secondary AB, but not with primary AB. The comparison of image 1B and 2B demonstrates specific binding of the primary anti‐PD‐L1 AB. The comparison of image 1A and 2A shows the autofluorescence upon excitation with a Hg lamp in combination with a 488 nm excitation filter. AB, antibody