IL-4/CD40L Co-Stimulation Induces Long-Term Proliferation for CD10- Positive Germinal Center B Cell-Like Diffuse Large B-Cell Lymphoma

Diffuse large B cell lymphoma (DLBCL) is a heterogeneous entity and the explicit mechanism of lymphomagenesis remains to be elucidated. CD40 ligand (CD40L, CD154) and interleukin-4 (IL-4) are important factors regulating B lymphocyte proliferation and differentiation; however, little is known about the effects of these factors on lymphomagenesis in DLBCL. In this study, we investigated the effects of these factors on DLBCL B cell proliferation. Normal (n=2) and DLBCL (n=10) B cells were cultured with a system containing IL-4 and CD40L-expressing NIH3T3 (CD40L + 3T3). Normal and tumor cells from six patients stopped growing within three weeks. Tumor cells, obtained from four patients with extranodal lesions, showed continuous proliferation for more than two months. Two cell lines were established from these cells. The cell lines were derived from gastric tissues showing CD10+ germinal center B-cell (GCB) phenotype. Removing IL-4 from the system or adding anti-CD40L blocking antibody inhibited the cell proliferation. An in vitro transwell assay showed that direct contact with CD40L + 3T3 was required for the proliferation. Our findings suggested that CD40L and IL-4 co-stimulation could induce long-term proliferation in B cells derived from some CD10+ GCB-like DLBCL patients with the same characteristics, and that direct stimulation from tumor microenvironment is important for the cell growth. These cell lines may be useful for investigating the growth mechanism of some type of DLBCL, and should provide new insights concerning pathogenesis of DLBCL.