Clinical indications and biological mechanisms of splenic irradiation in autoimmune diseases

Background: Splenic irradiation (SI) is a fairly unknown treatment modality in autoimmune disorders Like autoimmune thrombocytopenia (AIT) or autoimmu ne hemolytic anemia (AIHA), which may provide an effective, Low toxic and c ost-effective treatment for selected patients. Patients, Materials and Methods: This article reviews the Limited experienc es on splenic irradiation in autoimmune thrombocytopenia by analyzing the c urrent studies including 71 patients and some preliminary reports on spleni c irradiation in autoimmune hemolytic anemia. Results: In autoimmune thrombocytopenia between 40 and 90% of all patients responded, but most of them relapsed within 4 to 6 months after splenic irr adiation. Between 10 and 20% of all patients had a sustained response. The efficacy of splenic irradiation in HIV-associated cases of thrombocytopenia is probably Lower than in other forms of autoimmune thrombocytopenia, but especially in this group immunosuppressive drug treatment of autoimmune thr ombocytopenia exposes some problems. In autoimmune hemolytic anemia there a re some case reports about efficacy of splenic irradiation. Toxicity of spl enic irradiation in both diseases was very moderate. Conclusions: For HIV patients, for elderly patients or patients at high ris k for complications following splenectomy splenic irradiation might be a tr eatment option. Splenic irradiation as preoperative treatment in patients n ot responding to or not suitable For immunosuppressive drugs prior to splen ectomy may be a promising mew application of splenic irradiation to reduce adverse effects of splenectomy in thrombocytopenic patients. A further anal ysis of the biological mechanisms underlying splenic irradiation may help t o improve patient selection, to optimize dose concepts and treatment schedu les and will improve understanding of radiotherapy as an immunomodulatory t reatment modality.