Figure 1.
Dose of adoptively transferred CD8+ T cells strongly correlates with in vivo antitumor treatment efficacy. (A) Sublethally irradiated B6 mice bearing 13 day established s.c. B16 tumors were left untreated as controls (×) or received 107 pfu of rFPhgp100 viral vaccine and exogenous rhIL-2 (36 μg/dose x 6 doses) in combination with 104 (△), 105 (◆), 106 (○), or 107 (■) in vitro-activated Pmel-1 CD8+ T cells. Results are presented as the mean measurements from 5 mice per group (± SEM) and are representative of 3 independently performed experiments. (B) Antigen-specific CD8+ cell dose correlates with the magnitude of regression for established subcutaneous B16 melanoma tumors on a semi-log plot. The slope of tumor regression (mm2/day) for individually treated mice is shown as a function of in vitro-activated Pmel-1 CD8+ T cell dose. All mice received identical host pre-conditioning, rFPhgp100 vaccination, and exogenous rhIL-2. Log regression analysis was performed to determine the best line of fit and the Correlation Coefficient (R2) and the significance of correlation (P) were calculated. R2 = 0.71, P < 0.03. (C) Survival curves of untreated mice and mice receiving, exogenous IL-2, rFPhgp100 vaccine, and titrated doses of in vitro-activated adoptively transferred Pmel-1 CD8+ T cells. * = P < 0.05, ** = P < 0.01 using Log-rank statistics. Survival data shown was derived from 2 pooled independently performed experiments.