Protocol for iterative indirect immunofluorescence imaging in cultured cells, tissue sections, and metaphase...

We present a protocol to generate highly multiplexed spatial data at cellular and subcellular resolutions using iterative indirect immunofluorescence imaging (4i). We describe streamlined steps for using 4i across fixed cultured cells, formalin-fixed paraffin-embedded (FFPE) tissue sections, and metaphase chromosome spreads. We detail procedures for sample preparation, antibody and DNA staining, immunofluorescence imaging, antibody elution, and image processing. This protocol is adapted for high-throughput analysis of fixed cultured cells and addresses sample-specific challenges such as intrinsic tissue autofluorescence and chromosome fragility. For complete details on the use and execution of this protocol for fixed cultured cells, please refer to Comandante-Lou et al.¹.