Fig. 6.
Combination of HA PD-1 Ig and hypofractionated radiation therapy (RT) reduces lung metastatic burden and promotes immunological memory responses. (A) Quantitation and visualization of metastatic lung nodules in treated mice that received below-the-knee amputation (B) Treatment plan to study memory response: C57BL/6 mice were injected subcutaneously with 105 Lewis lung carcinoma (3LL) cells (black arrow) and treated as previously described. Mice that were “cured” were re-challenged at day 57 with 1 × 105 3LL cells in the left foot, monitored and sacrificed and day 66 for memory responses study. As a control for tumorigenicity, naïve control mice were inoculated with the same number of 3LL cells. (C) Measurement of cumulative and individual tumor volumes in naïve and RT + HA PD-1 Ig mouse groups. Tumor volumes were recorded 2–3 times per week. Data are representative of two independent experiments (n = 4–5/group); mean ± SD is shown. (D) Tumor growth delay (TGD). (E) Representative flow cytometry dot plots of effector memory (TEM, CD44hiCD62Llo) and central memory (TCM, CD44hiCD62Lhi) CD8 and CD4 T cells from spleen and dLN. Numbers in each quadrant indicate the relative percentage of population. Adjacent scatter plots represent the frequency of memory subsets reported per mouse. Bracketed lines indicate means. Data are representative of 2 independent experiments (n = 3–5/group). *p < 0.05, **p < 0.01 (Student's t-test).