CD4 and meningioma: We subsequently evaluated the presence of immune cell infiltrates in the tumour microenvironments of NF2-altered meningiomas by quantitative immunostaining for the immune cell markers CD3, CD4, CD8, CD19, CD45, CD68, CD163, FOXP3, and granzyme B (Fig. 4A–L, Additional file 1: Figures S9, 13).