Collaboration of T helper (Th) cells with B cells is central for the generation of high-affinity antibodies with distinct effector function and thus for the establishment of effective immune responses. Physiological T cell help for B cells takes place in germinal centers (GC) in peripheral lymphoid organs, where follicular T helper (Tfh) cells interact with mature, antigen-stimulated B cells. Occasionally, B cells undergo malignant transformation, which may lead to the development of leukemia or lymphoma. Over the past decades, it has become increasingly clear that cancer cells depend on interactions with the tumor microenvironment for growth and survival. Since many B cell malignancies develop in GC—the place of physiological Th cell-B cell interaction—Th cells are a central part of the tumor microenvironment of B cell leukemia and lymphoma. Thus, while the interaction between Th cells and normal B cells is crucial for the development of an effective immune response, this interaction also contributes to the development and pathogenesis of malignancies. The present chapter discusses the mechanisms underlying Th cell-mediated support of malignant B cells contributing to the pathogenesis of leukemia and lymphoma. Research efforts aiming to elucidate such mechanisms are of high importance as therapeutic targeting of these malignant interactions may increase treatment efficiency and reduce disease relapse.
Part of the book: Lymphocyte Updates