الفهرس 
Psoriasis VulgarisOnly 14 pages are availabe for public view
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Abstract
Background: Psoriasis vulgaris is a common, chronic immune-mediated skin disease characterized by red, scaly patches, papules, and plaques, which are usually itchy. The skin lesions seen in psoriasis may vary in the degree of severity from minor localized patches to complete body coverage. Psoriasis is estimated to affect 2-4% of the population. The rate of psoriasis occurrence varies according to age, gender, region and ethnicity with a combination of environmental and genetic factors thought to be responsible for these differences. CD200 is a type I transmembrane glycoprotein belonging to the immuno- globulin superfamily. It consists of extracellular, transmembrane, and intracellular domains. CD200 receptors involve CD200R1 to CD200R4, of which CD200R1 has the highest binding affinity. CD200 is more commonly expressed on the cells originating and emerging from the hematopoietic cells, more specifically those of the myeloid lineage such as macrophages, dendritic cells, neutrophils, eosinophils, and mast cells, yet it can be also expressed on B cells and activated T cells. This molecule produces its effect by binding to its receptor. This interaction can only occur when the cells expressing CD200 and the cells carrying the receptor are in close contact to each other.
Objectives: There was a preliminary study that assessed CD200 in the serum of psoriasis patients by ELISA kits and approved that the serum CD200 level was statistically significantly increased in patients with psoriasis vulgaris. The aim of this thesis was to evaluate the expression of CD200 protein in psoriasis skin lesions through immuno-histochemical study to assess its possible involvement in the pathogenesis of the disease.
Patients and methods: This study included two groups: group I: 15 psoriatic patients of psoriasis vulgaris. They were 11 males (73.3%) and 4 females (26.7%) with ages ranging from 14 to 61 years with a mean of 46.1± 15.2 years ; and group II: 15 healthy control subjects divided into 8 males (53.3%) and 7 females (46.7%) with ages ranging from 20 to 60 years with a mean of 40.53± 13.79 years. Five mm punch skin biopsy was taken from the lesional skin of patients and from normal skin of controls to assess the CD200 expression in tissues by immunohistochemistry. Evaluation of psoriasis severity in patients by “Psoriasis Area and Severity Index” (PASI) score was also done.
Results: There was a high statistically significant difference between cases and controls as regard percent and intensity of stained cells, where CD200 expression was higher among controls compared to cases. CD200 expression was also negatively correlated with PASI score.
Conclusion: the present study points to a potential link between psoriasis vulgaris and CD200 protein with lower skin expression in patients than in controls. It shows a negative relation with psoriasis severity index (PASI score). Such a link may help to further explore the complex pathogenesis of psoriasis. CD200 may be used as a beneficial biomarker and therapeutic agent in inflammatory responses in autoimmune situations and inflammatory skin disorders.