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 immunologic manipulation with noninvasive, longitudinal imaging, we generated a penetrant double oncogene-driven autochthonous model of neuroblastoma. Spatial transcriptomic analysis showed that CD4(+) and myeloid populations colocalized 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(+) T cells, or natural killer (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 protumorigenic pathways could be disabled by targeting myeloid arginine metabolism. Significance: A new model of human neuroblastoma provides ways to track tumor formation and expansion in living animals, allowing identification of CD4(+) T-cell and macrophage functions required for oncogenesis. [GRAPHICS]