Increased eosinophilic responses in splenectomized patients

BackgroundThe spleen is a key organ within the immune system. Its removal is known to bring about adverse effects such as an increased susceptibility to overwhelming infection. Few reports have suggested that the spleen may play a role in controlling eosinophilic responses, mostly based on animal models.ObjectivesTo examine whether the human spleen impacts eosinophil numbers in the blood.MethodsWe have retrospectively analyzed eosinophil counts and medical records of 29 patients who had undergone splenectomy between 2000 and 2010. Statistical comparison was performed between post-splenectomy blood counts and both pre-splenectomy and control values. Data regarding the clinical settings around hypereosinophilia events were obtained from patient charts.ResultsAn increased rate of eosinophilia was observed after splenectomy as compared with normal individuals. Furthermore, a considerable proportion of patients who had undergone splenectomies (8/29) presented peak eosinophil numbers exceeding 1,000/mm³, reaching a maximum of 3,070/mm³. These values were mostly encountered perioperatively or during episodes of acute infection.ConclusionsOur data indicate that impaired control of eosinophilic responses is a long-term post-splenectomy effect and is evident in the context of acute stress. We suggest that the spleen plays a significant role in controlling eosinophil levels and that these cells may mediate some of the harmful consequences observed after removal of the spleen.