CD4 and non-small cell lung carcinoma: As shown in Fig. 2, in primary NSCLC and paired brain metastases, the median of PD-1+ TILs were 11.7 (IQR 5.7–20) and 3.3 (IQR 0.7–11.3) (P = 0.106), the median of CD3+ TILs were 46.7 (IQR 12.5–118.4) and 9.0 (IQR 1.5–31.7) (P = 0.045), median of CD4+ TILs were 11.7 (IQR 1.7–31.7) and 1.7 (IQR 0.0–7.8) (P = 0.037), median of CD8+ TILs were 20.0 (IQR 11.0–55.9) and 2.7 (IQR 0.0–9.7) (P = 0.008), and median of CD20+ TILs were 3.3 (IQR 0.2–28.4) and 0.0 (IQR 0.0–3.3) (P = 0.029).