Although the precise pathogenesis of atopic dermatitis has not yet been entirely elucidated, various immunological features have been proposed as a markers of inflammation in AD. Total serum IgE is increased in 80% of patients and elevated values are loosely associated with more severe disease. Activated eosinophils, which are increased in the blood and affected skin are widely held reponsible for the tissue damage in AD. One of the most important toxic proteins released from these cells, eosinophil cationic protein (ECP), has been shown to reflect disease activity.
It has recently been reported that cell adhesion molecules on postcapillary endothelium play pivotal roles in the recuritment of leucocyte blood cells to the tissue site. Cytokines, such as tumour necrosis factor- (TNF-) and IL-1, induce the expression of distinct endothelial cell adhesion molecules. Leucocyte-endothelial cell interactions through adhesion molecules induce rolling, adhesion and migration of leucocytes to endothelial cells. E-selectin, VCAM-1 and ICAM-1 are such adhesion molecules. After they are expressed on endothelial cells, they are released into the circulation through shedding or by proteolytic mechanisms. Consequently, soluble forms of these adhesion molecules can be detected in the circulation, and are known to be among markers useful in monitoring the inflammation activity of AD.
Among the soluble adhesion molecules (sICAM, sVCAM-1 and sE selectin), sE-selectin appeared to be the most sensitive parameter in monitoring the clinical course of AD.
Thirty five patients were enrolled in the study (20 males and 15 females). Complete history taking; dermatological and general examination; diagnosis as having AD by fulfilling the UK refinement of Hanifin and Rajka’s diagnostic criteria for AD, disease severity determination by modified SCORAD index and measurement of sE-selectin, total IgE, specific IgE against D1, F1 and ECP in the sera of the patients were performed. Ten age and sex matched normal control subjects was also included in the study.
Soluble E-selectin, total IgE and ECP serum levels were significantly higher in patients with AD than in normal control subjects.
Serum level of sE-selectin was increased in all moderate and severe cases. Among mild cases serum level was at its higher limit and was significantly higher than in normal controls.
Also, it was evident that sE-selectin level fluctuates in accordance with the severity of the disease and it was significantly higher in patients with severe disease than in those with mild and moderate disease.
Serum level of total IgE was increased above age specific limits in 28 of 35 patients. Mean level of total IgE was significantly higher in patients with severe disease than in patients with mild and moderate disease. Mean SCORAD index in patients with mild, moderate and severe disease that had abnormal serum level of total IgE was insignificantly higher than in those with normal total IgE, this was not evident in patients with moderate and mild disease. This in our opinion means that total IgE can’t be considered as a useful marker for disease severity in patients with AD.
As regard specific IgE against D1 and F1 it was positive in 10 of 25 patients, detection of specific IgE antibodies against D1 and F1 was only evident in patients with increased disease activity (moderate and severe cases).
Mean titre of specific IgE antibodies in the low and high RAST class was insignificantly higher in severe disease than in moderate disease. But, this was not evident in the moderate RAST class against D1.
Mean titre of specific IgE against F1 in patients with high and moderate RAST class was higher among patients with severe disease than in those with moderate disease with statistically insignificant difference.
This may give an idea that although specific IgE was only detected in moderate and severe cases, its titre didn’t reflect disease severity.
As regard ECP, in our study ECP was significantly increased in the sera of 24 of 35 patients with atopic dermatitis and its serum level was significantly increased in patients with severe disease than in patients with mild and moderate disease. Also serum level of ECP was correlated with the SCORAD index and sE-selectin levels.
In conclusions, sE-selectin seems to be a useful marker in monitoring disease activity in patients with AD, as its level changes in accordance with the severity of the disease and it seems that, it is more useful than the other studied parameters especially total and specific IgE.
Also we like to mention the importance of standardization of severity assessment in patients with AD by using modified SCORAD index.
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