Neuroblastoma formation requires unconventional CD4 T cells and Arginase-1-dependent myeloid cells.

Immune cells regulate tumor growth by mirroring their function as tissue repair organizers in normal tissues. To understand the different facets of immune-tumor collaboration through genetics, spatial transcriptomics, and immunological manipulation with non-invasive, longitudinal imaging, we generated a penetrant double oncogene-driven autochthonous model of neuroblastoma. Spatial transcriptomic analysis showed that CD4+ and myeloid populations co-localized within the tumor parenchyma, while CD8+ T cells and B cells were peripherally dispersed. Depletion of CD4+ T cells or CCR2+ macrophages, but not B cells, CD8+, or NK cells, prevented tumor formation. Tumor CD4+ T cells displayed unconventional phenotypes and were clonotypically diverse and antigen-independent. Within the myeloid fraction, tumor growth required myeloid cells expressing arginase-1. Overall, these results demonstrate how arginine-metabolizing myeloid cells conspire with pathogenic CD4+ T cells to create permissive conditions for tumor formation, suggesting that these pro-tumorigenic pathways could be disabled by targeting myeloid arginine metabolism.