IL-21-driven neoplasms in SJL mice mimic some key features of human angioimmunoblastic T-cell lymphoma.

SJL/J mice exhibit a high incidence of mature B-cell lymphomas that require CD4(+) T cells for their development. We found that their spleens and lymph nodes contained increased numbers of germinal centers and T follicular helper (TFH) cells. Microarray analyses revealed high levels of transcripts encoding IL-21 associated with high levels of serum IL-21. We developed IL-21 receptor (IL21R)-deficient Swiss Jim Lambart (SJL) mice to determine the role of IL-21 in disease. These mice had reduced numbers of TFH cells, lower serum levels of IL-21, and few germinal center B cells, and they did not develop B-cell tumors, suggesting IL-21-dependent B-cell lymphomagenesis. We also noted a series of features common to SJL disease and human angioimmunoblastic T-cell lymphoma (AITL), a malignancy of TFH cells. Gene expression analyses of AITL showed that essentially all cases expressed elevated levels of transcripts for IL21, IL21R, and a series of genes associated with TFH cell development and function. These results identify a mouse model with features of AITL and suggest that patients with the disease might benefit from therapeutic interventions that interrupt IL-21 signaling.