Immune checkpoint expression and relationships to anti-PD-L1 immune checkpoint blockade cancer immunotherapy efficacy in aged versus young mice.

Age affects IC expression on specific immune cells in an organ- and tissue-specific manner. ICs were generally higher on aged immune cells. High immune-cell PD-1 could help explain PD-1 efficacy in aged. High co-expression of CD80 with PD-L1 on dendritic cells could help explain lack of PD-L1 efficacy in aged hosts. Factors other than myeloid cells and interferon- also affect age-related IC expression and T cell function, meriting additional studies.