Figure 1. Depletion of Treg cells increased the anti-melanoma effects of TA99 mAb.

C57BL/6 mice were treated with TA99 (anti-TYRP1) and PC61 (anti-CD25 depleting antibodies) beginning five days after s.c. or i.v. tumor cell injection (A). Subcutaneous tumor size was measured three times per week. Growth curves over time after grafting (days) are shown (B), and representative images of mice in different groups are shown (C). Flow cytometry analysis of these tumors showed a significant decrease in Treg cells infiltration (D). In the metastasis model, lungs were harvested on day 21 after tumor cell injection and metastatic nodules were counted (E). Images of lungs fixed in Fekete’s solution are shown (F). The combination of TA99 mAb with antibody-dependent Treg depletion (anti-CD25) reduced the growth of subcutaneous tumors, and lung metastases burden; mean ± SEM is shown. Significance was determined by two-way ANOVA with Bonferroni correction (B and D), or unpaired t test (E). n = 3 mice per group in (B–D), and 5 mice per group in (E) (representative from two experiments with similar results). ^** p < 0.001; ^*** p < 0.0001.