(A) The absolute number of dead KMS-12 PE cells was calculated for each sample condition of co-cultured CIKs and KMS-12 PE cells exposed to various concentrations of CBD for 24 h via flow cytometry analysis. The results showed a significant decrease of the absolute number of the dead KMS-12 PE cells at 5 µM (p < 0.05), 10 µM, and 15 µM (p ≤ 0.01) compared to the DMSO control. (B) The cytotoxicity of the effector CIKs against target KMS-12 PE cells exposed to various concentrations of CBD for 24 h was analyzed via LDH assay. The results of the LDH assay showed a significant decrease of the LDH release at 10 µM and 15 µM (p ≤ 0.001) compared to the DMSO control. (C) The absolute number of alive CIK cells (CD3+CD56+ NKT cells population) was calculated for each sample condition of co-cultured CIKs and KMS-12 PE cells exposed to various concentrations of CBD for 24 h via flow cytometry analysis. The results showed a significant decrease of the absolute number of the alive CIK cells compared to the DMSO control (p ≤ 0.01) and a significant increase of the absolute number of the alive CIK cells at 1 µM (p < 0.001), 3 µM (p ≤ 0.001), 5 µM (p ≤ 0.001), and 10 µM (p ≤ 0.01) compared to the DMSO control. There was a significant decrease at 20 µM (p ≤ 0.01).