ALA hydrochloride powder was obtained from Shanghai Fudan-Zhangjiang Bio-Pharmaceutical (Shanghai, People’s Republic of China [PRC]). ALA-loaded PLGA NPs (ALA PLGA NPs) were prepared using a modified double-emulsion solvent-evaporation method as previously described.8 (link) Encapsulation efficiency was 65.8%±7.2%, and ALA-loading capacity was 0.62%±0.27%. Sheep antimouse monoclonal antibody against CD4 and CD8, peroxidase-conjugated rabbit antisheep IgG, a Strept Avidin Biotin Complex kit, and 3,3′-diaminobenzidine (DAB) chromogen were obtained from Boster Biological Technology (Wuhan, PRC).