Non-human primate ( NHP) models, especially involving macaques, are considered important models of human immunity and have been essential in preclinical testing for vaccines and therapeutics. Despite this, much less characterization of macaque Fc receptors has occurred compared to humans or mice. Much of the characterization of macaque Fc receptors so far has focused on the low-affinity Fc receptors, particularly Fcγ RIIIa. From these studies, it is clear that there are distinct differences between the human and macaque low-affinity receptors and their interaction with human IgG. Relatively little work has been performed on the high-affinity IgG receptor, Fcγ RI, especially in NHPs. This review will focus on what is currently known of how Fcγ RI interacts with IgG, from mutation studies and recent crystallographic studies of human Fcγ RI, and how amino acid sequence differences in the macaque Fcγ RI may affect this interaction. Additionally, this review will look at the functional consequences of differences in the amino acid sequences between humans and macaques. [ABSTRACT FROM AUTHOR]