SIRPA and esophageal squamous cell carcinoma: To investigate the spatial connection of SPP1 + SIRPα + macrophages with tumor cells and CD8 + T cells, we conducted in-situ mIHC staining in 39 ESCC patients from ESCC cohort 1 using antibodies against CD68, SIRPα, SPP1, panCK, PD-1, and CD8 (Fig. 4A).