PDCD1LG2 and neoplasm: A recent study showed that in young hosts, macrophage PD-L2 expression was upregulated following αPD-L1 ICI and combining αPD-L1 with αPD-L2 improved anti-tumor immunity.46 To investigate PD-L2, we found that splenic DC (Figure 2A), macrophage (Figure 2B) PD-L2 expression prevalence, and MFI (Figure S1D) were similar in young and aged tumor-naïve mice.