In recent years, new findings in immunology have been successfully converted to therapeutic principles, in particular for rheumatoid arthritis (RA) and spondylarthritides. The introduction of cytokine blockers in RA using tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 inhibitors presented the first original therapy modalities in rheumatology, after proliferation-inhibiting drugs, such as methotrexate and cyclophosphamide, had been accepted in oncology. This advance was and is still being extended with the co-stimulation blockade using abatacept and IL-6 receptor inhibition. Anti-CD20 therapies are of particular importance, initially approved for the treatment of non-Hodgkin's lymphoma (NHL), this therapy modality has been approved in recent years for the treatment of RA following the failure of TNF-blockade. However, questions remain regarding the role of B cells in a number of autoimmune diseases, as well as the working principles of B-cell targeted therapy. In this context, close clinical observation of patients has yielded answers to and confirmation of basic scientific concepts.