Fig. 2

Microglial enrichment is consistent across pilocytic astrocytoma, can be quantified immunohistochemically, and includes anti-inflammatory phenotypes. When longitudinal changes in enrichment scores for microglial gene sets per patient are assessed by gene set variation analysis, all patients with expression data (n = 11) demonstrate an increase over time (a). Subsequent immunohistochemistry demonstrates longitudinal increases in myeloid/microglial markers CD68 and IBA1, which are concurrent with rises in M2-like/anti-inflammatory markers CD163 and TREM2 (b). Microglial enrichments appear only partially related to treatment modality. When patients are stratified according to treatment received at any timepoint between samples, a larger increase in CD68+ cells is associated with receipt of radiotherapy (c). However, this effect was not replicated for IBA1+ cell increases (d)