Using the Spleen as an In Vivo Systemic Immune Barometer Alongside Osteosarcoma Disease Progression and Immunotherapy with α-PD-L1

Table 1

Specific cell populations discussed and their corresponding defining markers.

Cell population	Defining markers
Tumor cells and stroma	CD45^−PD-L1^±
Cytotoxic T lymphocyte	CD45^+CD8^+
T helper lymphocyte	CD45^+CD4^+
Myeloid lineage cell	CD45^+CD11 b^+
Granulocyte	CD45^+CD11 b^+Ly6G^+Ly6C^−
Monocyte/macrophage	CD45^+CD11 b^+Ly6C^+Ly6G^−
Exhausted cytotoxic T lymphocyte	CD45^+CD8^+ PD-1^±Tim-3^±
Exhausted T helper lymphocyte	CD45^+CD4^+PD-1^±Tim-3^±
CTLA-4-expressing cytotoxic T lymphocyte	CD45^+CD8^+CTLA-4^+
M1-like macrophage	Cxcl9^±Nos2^±
M2-like macrophage	Arg1^±Tgm2^±

PD-L1 = programmed death-ligand 1; PD-1 = programmed cell death protein 1; Tim-3 = T-cell immunoglobulin and mucin-domain containing-3; CTLA-4⁺ = cytotoxic T-lymphocyte-associated protein 4; Cxcl9 = chemokine (C-X-C) motif ligand 9; Nos2 = nitric oxide synthase 2; Arg1 = arginase 1; Tgm2 = transglutaminase 2.