In vivo disruption of tolerogenic cross-presentation mechanisms uncovers an effective T-cell activation by B-cell lymphomas leading to antitumor immunity

Bone marrow-derived antigen-presenting cells (APCs) play a central role in the induction of tolerance to tumor antigens expressed by B-cell lymphomas. Here we show that in vivo disruption of this APC-mediated tolerogenic mechanism unveils an intrinsic ability of malignant B cells to efficiently present tumor antigens to antigen-specific CD4(+) T cells, resulting in a strong antitumor effect. This intrinsic antigen-presenting ability of malignant B cells is, however, overridden by tolerogenic bone marrow-derived APCs, leading instead to T-cell unresponsiveness and lack of antitumor effect. These results highlight the concept that therapeutic strategies aimed at enhancing the antigen-presenting function of B-cell lymphomas might not succeed unless the tolerogenic mechanisms mediated by bone marrow-derived APCs are disrupted in the first place.