IL4 and cancer: This is consistent with our finding of increased GCSF in tumours from female mice, as GCSF supports increased Th2 polarisation.31 While IL-4, produced by Th2 cells, has pro-tumour behaviour, particularly by supporting cancer stem cells,32 tumour-specific Th2 responses can also help eliminate tumours by reinforcing anti-tumour CD8+ T cell activity.33 We found that the increased Th2 and Th2-associated AAM correlated with improved survival, supporting the hypothesis that the Th2 axis within metastatic CRC could support anti-tumour immune activity.