Immunohistochemistry is commonly distinguished as being the process of conducting immunoreactions on tissue thin sections, whereas immunocytochemistry is the same type of reactions on cell cultures. Furthermore, the term immunofluorescence is also often applied to immunochemical reactions that involve fluorophores conjugated to primary and secondary antibodies, as well as antibody fragments. In the scientific literature and the catalogs of antibody manufacturers, these terms are useful to segregate between products designed for cytological use and those targeted at paraffin or frozen tissue sections. However, the general principles of immunology are the same regardless of whether they are applied to isolated cells or those embedded within a tissue matrix.

The log phase LLC-PK1 cells illustrated above were bathed in growth medium containing MitoTracker Red CMXRos for one hour, and then fixed, permeabilized, and blocked with 10-percent normal goat serum. The culture was subsequently treated with mouse anti-cytokeratin (pan) primary antibodies followed by goat anti-mouse secondary antibodies conjugated to Marina Blue. DNA in the nuclei was visualized using SYTOX Green. Images were recorded in grayscale with a QImaging Retiga Fast-EXi camera system coupled to an Olympus BX-51 microscope equipped with bandpass emission fluorescence filter optical blocks provided by Omega Optical. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.