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CD200, a transmembrane type Ia glycoprotein belonging to the immunoglobulin protein superfamily, is broadly expressed on a wide variety of cell types, such as B lymphocytes, a subset of T lymphocytes, dendritic cells, endothelial and neuronal cells. It delivers immunosuppressive signals through its receptor CD200R, which is expressed on monocytes/myeloid cells and T lymphocytes. Moreover, interaction of CD200 with CD200R has also been reported to play a role in the regulation of tumor immunity. Overexpression of CD200 has been reported in chronic lymphocytic leukemia (CLL) and hairy cell leukemia but not in mantle cell lymphoma, thus helping to better discriminate between these different B cell malignancies with different prognosis. In this review, we focus on the role of CD200 expression in the differential diagnosis of mature B-cell neoplasms and on the prognostic significance of CD200 expression in CLL, where conflicting results have been published so far. Of interest, increasing evidences indicate that anti-CD200 treatment might be therapeutically beneficial for treating CD200-expressing malignancies, such as CLL. [ABSTRACT FROM AUTHOR]

CD200, a transmembrane type Ia glycoprotein belonging to the immunoglobulin superfamily, has been shown to have a differential expression in B-cell neoplasms. Here, we retrospectively assessed the diagnostic relevance of CD200 on 427 patients with B-cell chronic neoplasms in leukemic phase (median age, 69 y; range, 35-97 y). The final diagnosis based on the investigator's assessment was chronic lymphocytic leukaemia (CLL) in 75% of cases and non-CLL in 25% of cases. Sensitivity and specificity for the diagnosis of CLL (vs non-CLL) were calculated for the following markers: CD200, CD5, CD22, CD23, CD79b, FMC7, and SmIg. CD23 was the only marker without a statistically significant difference between the investigator assessment and the flowcytometric analysis. The other markers were unable-when individually evaluated-to discriminate between CLL and non-CLL, requiring the integration into a scoring system. The modified score no. 1 (addition of CD200) showed superimposable sensitivity and specificity compared with the Matutes score. The substitution of CD79b (modified score no. 2), surface membrane immunoglobulins (SmIg) (modified score no. 3), and CD79b and FMC7 (modified score no. 4) with CD200 showed that only the modified score no. 4 had both higher sensitivity and higher specificity compared with standard Matutes score. In conclusion, this work defines a simplified score, compared with the classical Matutes score, for the differential diagnosis of chronic B-cell leukaemia-which only requires 4 markers instead of 5 (CD5, CD23, CD200, and SmIg). [ABSTRACT FROM AUTHOR]

The frequency and function of regulatory T-cells (Tregs) in multiple myeloma (MM) are still matter of debate. The percentage and absolute number of circulating Tregs (CD4(+)CD25(+high  density)CD127(-/low  density)) from 39 patients with untreated MM and 44 patients with monoclonal gammopathies of uncertain significance (MGUS) were tested and compared with 20 healthy subjects as controls. The mean percentage number of circulating Tregs was 2.1%  ± 1.0 (range 0.75-6.1%) in MM patients; 2.1%  ± 0.9 (range 0.3-4.4%) in MGUS; and 1.5%  ± 0.4 (range 0.9-2.1%) in controls (p ns). Mean absolute number of Tregs was 36.3/μL ± 23.7 (range 6.7-149/μL) in MM; 38.8/μL ± 19.1 (range 4.3-87/μL) in MGUS; and 39.4/μL ± 12.5 (range 18-63/μL) in controls (p ns). After a median follow-up of 38 months, 5 MGUS and 2 smoldering MM (SMM) transformed into overt MM; however Tregs number did not predict this evolution. With respect to MM patients and after a median follow-up of 33 months, Tregs did not show any significant correlation with main clinical and laboratory characteristics. Finally, from a functional point of view, Tregs displayed an effective suppressor function, irrespective of disease status. This study indicates that the number of circulating Tregs does not differ in different monoclonal gammopathies and normal subjects and do not correlate with clinical features of MM. [ABSTRACT FROM AUTHOR]