Figure 3.

In vivo cross-validation of ⁸⁹Zr-h/mCD4-Mb to visualize endogenous CD4⁺ cells in lymphatic organs. (A) Treatment and PET imaging schedule. hCD4-KI and WT animals were orthotopically inoculated with 0.5 x10⁶ PyMT cells in the 4^th mammary fat pad and treated with a combination of the αPD-1/α4-1BB mAbs (200 μg/50 μg per mouse). PET/MRI was performed 3 and 4 days after treatment onset (24 h and 48 h after i.v. injection of ⁸⁹Zr-h/mCD4-Mb). (B) Representative PET/MR images of the spleen (left, separated from the kidney/liver derive uptake by a white broken line) and lymph nodes (right, white triangle) acquired 48 h post-tracer injection. k: kidney; li: liver; t: tumor. (C) In vivo quantification of human and murine ⁸⁹Zr-CD4-Mb uptake in lymphatic organs (spleen, draining lymph node (dLN), and contralateral non-draining lymph node (ndLN)) 48 h post tracer injection. (D) Ex vivo quantification of ⁸⁹Zr-h/mCD4-Mb uptake in lymphatic organs 48 h post tracer injection. P values were calculated by an unpaired t-test. Data derived from two independent experiments (n = 4-6 per group). *p < 0.05, **p < 0.01, ***p < 0.001.