IL-10 from tumoral B cells modulates the diffuse large B-cell lymphoma microenvironment and response to immunotherapy.

The contribution of interleukin-10 (IL-10), secreted by tumoral B cells, to the progression and shaping of the microenvironment in diffuse large B-cell lymphoma (DLBCL) with activated B-cell-like (ABC) phenotype is not yet completely understood. To shed light on this issue, we generated an immunocompetent mouse model of ABC-DLBCL with conditional knockout of IL-10 specifically in malignant B cells. Paradoxically, these mice had significantly worse overall survival when left untreated but experienced increased sensitivity to conventional anti-CD20 immunotherapy or regulatory T-cell depletion. We identified various immunomodulatory mechanisms involved in this behavior. In particular, we show that IL-10-deficient lymphomas acquire a highly immunosuppressed and T-cell-exhausted microenvironment with increased angiogenesis that results in a more aggressive phenotype, which is refractory to PD-1 immune checkpoint blockade. However, the response of IL-10-deficient mice to anti-CD20 immunotherapy was greatly enhanced by upregulation of calcium channels in B cells. In general, IL-10 autocrine signaling promotes the survival of malignant B cells, whereas the paracrine action of B-cell-derived IL-10 maintains an immunoreactive microenvironment that influences the efficacy of emerging immunotherapy strategies targeting the lymphoma microenvironment. Furthermore, IL-10-associated transcriptional signatures derived from our studies may correctly predict clinical outcomes of patients with DLBCL treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone). Thus, our work provides important functional and mechanistic insights into the role of B-cell-derived IL-10 in the biology of ABC-DLBCL.