The microenvironment in follicular lymphoma.

It has become increasingly clear that proliferation and survival in FL is not only driven by genetic changes, but also and possibly even predominantly by the close interaction with the immune microenvironment and stromal cells. Based on in vitro studies and experimental models and supported by immunohistochemical studies in biopsy specimens of FL patients, classes of CD4+ T-cell populations including follicular helper T cells and regulatory T cells are now identified as major players to regulate the delicate balance of effector populations into a supportive microenvironment. These insights may thoroughly change the therapeutic approaches in FL and translate into programs that combine direct cytotoxic and indirect immunomodulatory aspects.