CD4 and lung cancer: To extend our spatial analyses of immune infiltrates in lung cancer brain metastases with an orthogonal approach, we performed mIHC staining on TCs from the same patients, on which we stained with five immune cell markers: CD4 (T-helper cells), CD8 (cytotoxic T cells), CD20 (B cells), FOXP3 (regulatory T cells, Tregs) and CD68 (macrophages; Fig. 2A).