CD80 and cancer: Interestingly, with nanoparticle flow cytometry, we found that more than half of circulating PD-1+ or CD80+ sEVs cocarried both PD-1 and CD80 (Fig. 1j), revealing a synchronised increase in sEV PD-1 and CD80 (hereafter PD-1/CD80) levels in the circulation of cancer patients.