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

Table 8

Treatment with α-PD-L1 dramatically affects macrophage maturation and M1/M2 polarization in the spleens of TF tumor-bearing mice.

Population	TF (−) α-PD-L1 % expression	TF (+) α-PD-L1 % expression	p
MLCs	5.27 ± 1.11%	5.73 ± 1.68%	0.65
Monocytes/macrophages	4.92 ± 1.29%	12.8 ± 2.92%	0.0016
Granulocytes	57.49 ± 9.62%	51.37 ± 9.11%	0.41
Tgm2^+ macrophages	18.58 ± 5.69%	2.1 ± 2.17%	0.0034
Arg1^+ macrophages	0.3 ± 0.56%	0.23 ± 0.17%	0.84
Cxcl9^+ macrophages	18.28 ± 5.38%	1.52 ± 1.24%	0.002
Nos2^+ macrophages	97.99 ± 1.62%	50.89 ± 18.07%	0.00086

Spleens were harvested at approximately 11 weeks post-inoculation and the tissue was subjected to Panel 4 for immune cell population analysis from n = 5 (−) α-PD-L1 and n = 3 (+) α-PD-L1 TF tumor-bearing mice. For treated mice, 20 ug of α-PD-L1 was given in PBS via intraperitoneal injection twice a week starting when tumors were first palpable. The statistics for each group are summarized accordingly with significance being assigned to those populations presenting values < 0.00714 from a two-tailed Student’s T-test with Bonferroni correction and 95% confidence as denoted by an asterisk. PD-L1 = programmed death-ligand 1; TF = transfected; MLC = myeloid lineage cell; Tgm2 = transglutaminase 2; Arg1 = arginase 1; Cxcl9 = chemokine (C-X-C) motif ligand 9; Nos2 = nitric oxide synthase 2.