CD4 and fibrosarcoma: In lung-infiltrating lymphocytes, in comparison to wild-type mice, GR9 fibrosarcoma-bearing mice exhibited a strong decrease in several immune cell subpopulations, with a significant reduction (p < 0.05) in TCD3+ (36.1 vs. 51.9%), TCD8+ (6.5 vs. 9.7%), and TCD4+ (29.6 vs. 40.6%) lymphocytes; moreover, a significant increase in Treg cells was found (8.9 vs. 2.9% of CD4+ cells) (Table 1).