CXCL-8/IL-8 produced by diffuse large B-cell lymphomas recruits neutrophils expressing a proliferation inducing ligand APRIL.

Tumor infiltrating neutrophils have been implicated in malignant development and progression but mechanisms are ill-defined. Neutrophils produce a proliferation-inducing ligand APRIL/TNFSF13, a factor that promotes development of tumors from diverse origins, including diffuse large B-cell lymphoma (DLBCL). High APRIL expression in DLBCL correlates with reduced patient survival, but the pathway(s) dictating APRIL expression are not known. Here we show that all blood neutrophils constitutively secrete APRIL, and inflammation-associated stimuli such as TNF further upregulate APRIL. In a significant fraction of DLBCL patients tumor cells constitutively produced the ELC-CXC chemokine CXCL-8 (IL-8), enabling them to recruit APRIL-producing blood neutrophils. CXCL-8 production in DLBCL was unrelated to the cell of origin, as APRIL-producing neutrophils infiltrated CXCL-8+ DLBCL from both germinal center (GC) and non-GC subtypes. Rather, CXCL-8 production implied events affecting DNA methylation and acetylation. Overall, our results showed that chemokine-mediated recruitment of neutrophils secreting the tumor-promoting factor APRIL mediates DLBCL progression.