Alpha-1-acid glycoprotein (AGP) is an acute-phase protein important in the immune response. It has been shown that AGP levels increase in cats with FIP, but also that some cats resistant to FIP may have transient increases in AGP. During the course of studying AGP, the researchers identified a similar protein called AGPrP. Cats with FIP appear to have decreased levels of AGPrP. It may be that AGPrP plays some role in susceptibility or resistance to FIP. As an acute-phase protein, AGPrP is found distributed throughout various tissues of healthy cats. AGPrP has also been demonstrated in the tissues of cats with FIP, including within the typical granuloma lesions. However, no correlation was seen between AGPrP presence and coronavirus. Further work remains to be done to characterize AGPrP and its role in FIP.