Current concepts of B cell modulation.

Three interleukins with distinct functions, IL-4, IL-5 and IL-6, are involved in the regulation of B cell response into antibody producing cells. The studies with recombinant interleukins, however, demonstrated that the activities of these interleukins were not restricted to B lineage cells but showed a wide variety of biological functions on various tissues and cells. One of the most typical example of multifunctional interleukins is IL-6. It acts not only on B cells as B cell differentiation factor but also on T cells, hematopoietic stem cells, hepatocytes, nerve cells and myeloma cells. Deregulation of the expression of these interleukins was shown to be responsible for various diseases, such as i) IL-4 vs. immediate type hypersensitivity and ii) IL-6 vs. autoimmunity and multiple myelomas.