Blockade of SCF/ckit pathway by the use of anti-ckit antibody or SCF knockdown of tumor cells results in decreased infiltration of MDSCs in tumor tissue and decreased tumor angiogenesis. (A) Immunostaining of Gr-1⁺ cells in wild-type versus SCF-silenced MCA26 tumor tissues. (B) Immunostaining of Gr-1⁺ cells in tumor tissues from HA-MCA26 tumor-bearing mice that were injected with rat Ig (left), 5 × 10⁶ HA-TCR T cells (middle), or 5 × 10⁶ HA-TCR T cells and anti-ckit (right). (C) Immunostaining of CD31⁺ cells in wild-type versus SCF-silenced MCA26 tumor tissues. (D) Immunostaining of CD31⁺ cells in tumor tissues from HA-MCA26 tumor-bearing mice that were injected with rat Ig (left), 5 × 10⁶ HA-TCR T cells (middle), or 5 × 10⁶ HA-TCR T cells and anti-ckit (right). Slides were viewed with a Leica DM RA2 fluorescent microscope (Leica Microsystems, Wetzlar, Germany) using an HC PLAN APO lens at 63×/1.32 (A,B) and 40×/0.85 (C,D) and Klear Mount medium (GBI, Mukilteo, WA). Images were acquired using a Hamamatsu ORCA-ER digital camera (Minneapolis, MN) Model C4742-80-12AG, and were processed with Openlab version 5.02 (Improvision, Waltham, MA) and Adobe Photoshop version 7.0 software (Adobe Systems, San Jose, CA).