Phagocytosis mediated by FcγRI/CD8 chimeras. The chimeric receptors RI-CD8-RI (EC-TM-CY) and RI-CD8-γ contain the TM of CD8. The RI-CD8/10N-RI chimera contains the first 10 aminoterminal amino acids of the CD8 TM and the 11 carboxyterminal amino acids of the FcγRI TM. The RI-CD8/14C-RI chimera contains the first 10 aminoterminal amino acids of the FcγRI TM and the 14 carboxyterminal amino acids of the CD8 TM (Figure 2). The phagocytic index (PI) values are expressed as % PI of FcγRI(RI) + γ. Receptor expression was monitored by flow cytometry. For RI + γ and each chimeric receptor, 3-5 experiments were performed. Of note, the cell surface expression of the extracellular domain of FcγRI in the chimera RI-CD8/14C-RI, which does not mediate phagocytosis with coexpression of γ, was equal to or greater than the surface expression of WT FcγRI + γ, RI-CD8-γ, or RI-CD8/10N-RI + γ, all of which mediate phagocytosis efficiently.