Study of CD200 in chronic lymphocytic leukemia

Background CD200 is a transmembrane protein expressed on multiple cell types (e.g. thymocytes, activated T cells, B cells, dendritic cells, and endothelial cells). It regulates antitumor immunity and its overexpression is associated with poor prognosis in chronic lymphocytic leukemia (CLL). A soluble variant of CD200 (sCD200) is detectable in human serum, and an elevated serum level was shown in patients with CLL. Objective The aim of the study is to investigate the relationship between the levels of CD200 and clinical staging in patients with CLL. Subjects and methods The study included 50 patients, divided into two groups. The patient group included 30 de-novo patients with CLL (18 men and 12 women), whose age ranged from 49 to 70 years with a mean±SD of 57.82±4.94 years. They were classified according to the modified Rai staging system into three classes: (a) low-risk patients, which included seven cases (stage 0); (b) intermediate-risk patients, which included eight cases (stages I and II); and (c) high-risk patients, which included 15 cases (stages III and IV). The control group included 20 individuals (14 men and six women), whose age ranged from 50 to 72 years with a mean±SD of 58.54±5.1 years. CD200 levels were measured by flow cytometry. Results Higher levels of CD200 were observed in the patient group compared with the control group. In addition, there was a significant increase of CD200 expression in the intermediate group of patients compared with low-risk patients, and a significant increase in the CD200 level in the high-risk group compared with intermediate-risk patients. Conclusion A positive correlation between the level of CD200 expression and clinical staging system of CLL was observed in our study; thus, measurement of CD200 may have a prognostic role in patients with CLL. In addition, it can be used as a follow-up marker for clinical response to treatment in CLL. CD200 blockade by immunotherapeutic agents may represent a novel approach for clinical treatment of CLL and a number of B-cell-derived neoplasms.