Tickling the CD200 receptor: A remedy for those irritating macrophages

CD200 expression in hematopoietic neoplasms: Beyond a marker for diagnosis of B-cell neoplasms

CD200 (OX-2) is expressed in myeloid cells, B cells, subsets of T cells and on other normal and neoplastic non-hematopoietic cells. It interacts with CD200R and has a suppressive effect on T cells immune mediated response. We aimed to review CD200 expression and its role in the immune evasion of non-B cell hematopoietic neoplasms. In acute myeloid leukemia, CD200 seems to be related to the worst outcome, even in diseases of good prognosis, possibly due to an immunosuppressive effect. In plasma cell myeloma studies, while some have associated CD200 expression with worst prognosis possibly due to its suppressive effect on monocyte and T cell-mediated immune response, in others CD200 appeared to be a marker of a better outcome, or even showed no impact in event-free survival (EFS). Few studies have evaluated CD200 expression in T cell neoplasms; however, it appears to be a good immunophenotypic marker for angioimmunoblastic T cell lymphoma. In conclusion, CD200 appears to be involved in the immune evasion of malignant cells, which could affect the survival of these patients.

CD200:CD200R Interactions and Their Importance in Immunoregulation

The molecule CD200, described many years ago as a naturally occurring immunomodulatory agent, capable of regulating inflammation and transplant rejection, has attracted additional interest over the past years with the realization that it may also serve as an important marker for progressive malignancy. A large body of evidence also supports the hypothesis that this molecule can contribute to immunoregulation of, among other diseases, infection, autoimmune disease and allergy. New data have also come to light to characterize the receptors for CD200 (CD200R) and their potential mechanism(s) of action at the biochemical level, as well as the description of a novel natural antagonist of CD200, lacking the NH₂-terminal region of the full-length molecule. Significant controversies exist concerning the relative importance of CD200 as a ligand for all reported CD200Rs. Nevertheless, some progress has been made in the identification of the structural constraints determining the interaction between CD200 and CD200R, and this information has in turn proved of use in developing novel small molecule agonists/antagonists of the interaction. The review below highlights many of these newer findings, and attempts to place them in the broad context of our understanding of the role of CD200-CD200R interactions in a variety of human diseases.

In silico investigation of novel biological pathways: the role of CD200 in regulation of T cell priming in experimental autoimmune encephalomyelitis

The use of simulation to investigate biological domains will inevitably lead to the need to extend existing simulations as new areas of these domains become more fully understood. Such simulation extensions can entail the incorporation of additional cell types, molecules or molecular pathways, all of which can exert a profound influence on the simulation behaviour. Where the biological domain is not well characterised, a structured development methodology must be employed to ensure that the extended simulation is well aligned with its predecessor. We develop and discuss such a methodology, relying on iterative simulation development and sensitivity analysis. The utility of this methodology is demonstrated using a case study simulation of experimental autoimmune encephalomyelitis (EAE), a murine T cell-mediated autoimmune disease model of multiple sclerosis, where it is used to investigate the activity of an additional regulatory pathway. We discuss how application of this methodology guards against creating inappropriate simulation representations of the biology when investigating poorly characterised biological mechanisms.