Figure 6.

Ex vivo validation of ⁸⁹Zr-mCD4-Mb uptake. (A) Ex vivo H&E staining of MC38 tumors from αPD-L1/αLag3-treated mice and representative immunofluorescence (IF) of CD3⁺ and CD4⁺ cells (field marked by a green star). Scale bars: 1000 µm H&E, 20 µm IF. (B) Quantification of % intratumoral CD4⁺ cells of all cells per field (5 fields per tumor) from αPD-L1/αLag3 responders (R, n = 4), non-responders (NR, n = 4) and sham-treated animals (n = 2). (C) Colocalization of intratumoral CD4 protein expression and ⁸⁹Zr-mCD4-Mb by secondary IF staining. Scale bar: 10 µm. *p < 0.05, **p < 0.01, ***p < 0.001.