Changing roles of eosinophils in health and disease.

OBJECTIVE: To review and highlight the unappreciated roles of eosinophils suggested by recent studies. DATA SOURCES: The literature, unpublished observations, and insights by the authors. STUDY SELECTIONS: Basic studies of mouse models and patient-based clinical studies of disease. RESULTS: Eosinophils are often thought of as destructive end-stage effector cells primarily linked to parasite host defense and dysregulated immune responses associated with allergic diseases, such as asthma. However, recent studies (ie, research focused on mechanisms of action and translational studies examining disease/inflammatory pathways) are suggesting far more complex roles for eosinophils. The goal of this review is 3-fold. (1) The authors examine the dynamic history of eosinophils and how physicians over time used this information to formulate defining hypotheses. Particular emphasis is placed on recent studies challenging the parochial view of host defense in favor of roles maintaining homeostasis through immune modulation and tissue remodeling/repair. (2) They discuss diagnostic approaches to assess eosinophils in clinical settings as a means of disease identification and subsequently as a measurement of disease severity. (3) They examine how contemporary views of eosinophils and their perceived roles in diseases have led to specific therapeutic strategies. The emphasis is to review the successes and failures of these strategies as the basis of formulating future clinical studies targeting eosinophils as potential therapies of disease. CONCLUSION: Despite the complexities of eosinophil-mediated activities and the less than overwhelming success of initial attempts targeting these cells, eosinophils remain a potentially important focal target of disease diagnosis and subsequent treatment strategies.

Treatment of hypereosinophilic syndromes--the first 100 years.

Treatment of the hypereosinophilic syndrome (HES) has advanced rapidly and prevention of end organ damage previously associated with the disorders is now possible in most patients who have had a timely diagnosis. Tried and true medications such as prednisone, hydroxyurea, and interferon-alpha (IFN-aα) continue to play a valuable role in treating HES and their cost is modest. Newer medications included pegylated forms of IFN-aα and IFN-α2b, first- and second-generation tyrosine kinase inhibitors (imatinib mesylate, nilotinib), and monoclonal antibodies to interleukin (IL)-5 and CD52. The combination of better understanding of HES and better medications now provide the clinician with an improved ability to control unregulated proliferation of eosinophils.

[New light shed on the enigmatic eosinophilic granulocyte. Both a friend and an enemy]. / Nytt ljus över den gåtfulla eosinofila granulocyten. Både vän och fiende.

Eosinophils normally constitute only a few per cent of circulating leucocytes, though they are more numerous in tissues vulnerable to attack by environmental micro-organisms. Eosinophils can kill invasive parasites, but also possess immunoregulatory functions and may be involved, for example, in the connective tissue remodelling that occurs in conjunction with inflammation. Although their effects may be beneficial to the host, for instance in the event of helminthic infestation, they may also cause tissue damage, for example in allergy and asthma. Recent years have witnessed manifest advances in our knowledge of these fascinating but still enigmatic cells.