Figure 5

Induction of a second CD11b⁺ MDSC subset by breast, lung, and brain cancer cell lines. A, CD11b⁺ cells from breast cancer, lung cancer, or glioma cell line-PBMC co-cultures were evaluated for suppressive function against CD3/CD28 stimulated autologous T cells. Mean (n = 2) T cell proliferation + SEM or T cell proliferation (n = 1) is shown from Suppression Assays of CD33⁺ or CD11b⁺ cells with autologous T cells, respectively. * indicates statistically significant suppression of T cells by CD11b⁺ cells from co-culture (p <0.05, ANOVA followed by Dunnett's test for comparison to T cells alone); significance for suppression by CD33⁺ cells is found in Table 1. Note that some tumor cell lines induce both subsets, while others induce only one subset or neither. CD33⁺ and CD11b⁺ cells from medium only cultures were not suppressive. B, CD11b⁺ MDSC subset can be induced from normal donor PBMC by cytokines FLT3L and TGFβ. Mean shown (n = 3) + SEM. * indicates statistically significant in mean T cell proliferation compared with T cells alone (p <0.05).