[The role of eosinophilic granulocytes for the pathogenesis of atopic dermatitis /neurodermatitis. Eosinophilic products as markers of disease activity].

Recent data provide increasing evidence for an immunological basis of atopic dermatitis (AD). Atopyspecific helper T cells (Th2-like T cells) may play a pathogenic role by producing and releasing cytokines that are relevant for the allergic inflammation, such as IL-4, IL-5 and other growth factors. It is suggested that eosinophils play a major role as effector cells mediating the pathogenetically important late-phase reaction, which is associated with significant destruction of the surrounding tissue. Accordingly, a significant preactivation of peripheral blood eosinophils was detected in AD patients, leading to enhanced susceptibility of these cells to distinct stimuli, such as IL-5. Toxic proteins, such as eosinophil cationic protein (ECP), which are contained in the matrix and the core of secondary granules of eosinophils, may play an important role by propagating the allergic inflammatory process and by exerting their direct immunomodulatory effects. A pathogenic role of eosinophils in AD is further supported by the detection of these proteins in eczematous skin of the patients. Furthermore, recent data indicate a significant correlation between disease activity and deposition of eosinophil granule content: ECP serum levels were significantly increased in AD patients. In addition, ECP levels correlated with the disease activity. Moreover, clinical improvement was associated with a decrease both in the clinical score and in serum ECP levels. These data clearly indicate that activated eosinophils are involved in the allergic inflammatory process in AD. Therefore, modulation of eosinophil activation could be an important pharmacologic modality for the treatment of AD in the future.