Chronic CD30-signaling in B cells results in lymphomagenesis by driving the expansion of plasmablasts and B1 cells

CD30 is expressed on a variety of B-cell lymphomas such as Hodgkin9s lymphoma, primary effusion lymphoma, and a subgroup of diffuse large B-cell lymphoma. In normal tissues, CD30 is expressed on some activated B and T lymphocytes. However, the physiological function of CD30-signaling and its contribution to the generation of CD30-positive lymphomas are still poorly understood. To gain a better understanding of CD30-signaling in B cells, we studied the expression of CD30 in different murine B-cell populations. We show that B1 cells express higher levels of CD30 than B2 cells and that CD30 is upregulated in IRF4+ plasmablasts (PB). Furthermore, we generated and analyzed mice expressing a constitutively active CD30-receptor in B lymphocytes. These mice displayed an increase of B1 cells in the peritoneal cavity (PerC) and in secondary lymphoid organs as well as increased numbers of plasma cells (PC). TI-2-immunization resulted in a further expansion of B1 cells and PC. We provide evidence that the expanded B1 population in the spleen includes a fraction of PB. CD30 signals appeared to enhance PC-differentiation by increasing activation of NF-κB, higher levels of phosphorylated STAT3 and STAT6 and of nuclear IRF4. In addition, chronic CD30-signaling led to B-cell lymphomagenesis in aged mice. These lymphomas were localized in the spleen and PerC and had a B1-like/plasmablastic phenotype. We conclude that our mouse model mirrors chronic B cell activation with increased numbers of CD30+ lymphocytes and provides experimental proof that chronic CD30-signaling increases the risk of B-cell lymphomagenesis.