CD4 and non-small cell lung carcinoma: To establish a brain metastasis-associated immune profile, the spatial distribution of infiltrating immune cells was evaluated in the peritumoral and intratumoral regions of BM tissues from patients with NSCLC by immunohistochemical (IHC) staining for CD3, CD8, CD4, FoxP3, and CD68 (Fig. 1a and Supplementary Fig. 5).