title: [Immunosuppressive treatment of rheumatic diseases. Experimental bases of a rational concept of therapeutic approach (author's transl)].
abstract: For treatment of diseases such as rheumatoid arthritis or systemic lupus erythematodes, which are initiated or sustained by immune-pathological mechanisms, various "immunosuppressive" drugs are used. There are conflicting data as to the benefit of this type of therapy. In this paper it is attempted to define a base for a more differentiated application of available drugs, since the present therapeutic approach seems rather empiric or is deducted from analogy to selected animal experiments. The investigations presented focus primarily on the behaviour of the small and medium lymphocytes of the organism, the adopted carriers of immunological (as well as autoimmune) reactivity, under conventional conditions (and under the influence of suitable drugs) as a biological supposition for the activity of "immunosuppressives". In rabbits, and mice, number and rate of proliferation of lymphoid cells is determined in untreated controls and animals treated with 6-mercaptopurine (6-MP) and cyclophosphamide (Cy), two immunosuppressive agents representing different types of pharmacological action. The elucidation why in rabbits both substances are equally immunosuppressive, whereas in mice only Cy has significant immunosuppressive activity, yields the base for a therapeutic concept of clinical immunosuppression. This species dependent activity of 6-MP can be explained by different proliferation kinetics of lymphoid cells in mouse and rabbit. Lymphocytes of the rabbit, compared to those of mice, are short-lived and have a distinctly higher proliferation rate. Thus, 6-MP, as an antiproliferative agent, leads, in the rabbit (under long-term as well as single-dose therapy) to a significant reduction of the number of small lymphocytes, whereas it reduces the long-lived lymphocytes of the mouse only marginally, thus explaining the good immunosuppressive potency in the rabbit and failure in the mouse. Cy leads, in both species, to a marked reduction of small lymphocytes and affects the long-lived cells of the mouse as well, resulting in high immunosuppressive potency in both species. In the NZB mouse, a well-fitting model of human lupus erythomatodes, Cy is successful in prophylaxis and therapy. A similar therapeutic effect cannot be obtained with 6-MP. Neither of the two groups of substances revealed selective activity on circulating T- or B-cells. According to the literature available, lymphocytes in humans are predominantly long-lived, too. Accordingly, Cy possesses a good immunosuppressive potency in man, too. Its therapeutic success is paralleled by a reduction of small lymphocytes. In conclusion, a true basic immunosuppressive therapy of autoimmune diseases in humans will primarily be possible by aid of substances which act through a cytotoxic mechanism and are thus able to affect even the long-lived human lymphocytes. In contrast, a substance acting purely through interference with certain steps of cell proliferation will predominantly remain restricted to an antiphlogistic use.
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D001327:Autoimmune Diseases; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003520:Cyclophosphamide / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D015122:Mercaptopurine / Q000494:pharmacology; D051379:Mice; D008814:Mice, Inbred NZB; D011817:Rabbits; D012216:Rheumatic Diseases / Q000188:drug therapy* / Q000276:immunology; D013045:Species Specificity
chemical_list: D007166:Immunosuppressive Agents; D003520:Cyclophosphamide; D015122:Mercaptopurine
vernacular_title: Immunsuppressive Behandlung der Erkrankungen des rheumatischen Formenkreises. Experimentelle Grundlagen für ein rationales Therapiekonzept