The Implication and Significance of Beta 2 Microglobulin: A Conservative Multifunctional Regulator

Abstract

Objective: This review focuses on the current knowledge on the implication and significance of beta 2 microglobulin (β2M), a conservative immune molecule in vertebrate.

Data sources: The data used in this review were obtained from PubMed up to October 2015. Terms of β2M, immune response, and infection were used in the search.

Study selections: Articles related to β2M were retrieved and reviewed. Articles focusing on the characteristic and function of β2M were selected. The exclusion criteria of articles were that the studies on β2M-related molecules.

Results: β2M is critical for the immune surveillance and modulation in vertebrate animals. The dysregulation of β2M is associated with multiple diseases, including endogenous and infectious diseases. β2M could directly participate in the development of cancer cells, and the level of β2M is deemed as a prognostic marker for several malignancies. It also involves in forming major histocompatibility complex (MHC class I or MHC I) or like heterodimers, covering from antigen presentation to immune homeostasis.

Conclusions: Based on the characteristic of β2M, it or its signaling pathway has been targeted as biomedical or therapeutic tools. Moreover, β2M is highly conserved among different species, and overall structures are virtually identical, implying the versatility of β2M on applications.

Figure 1

Schematic representation of MHC I antigen presentation to CD8 T-cell. MHC I consists of two polypeptide chains, α (α1, α2, α3) and β2M, which are noncovalently linked between α3 and β2M. The peptides (antigens) generated from cytosolic proteins bind the polymorphic groove between α1 and α2 and are displayed to CD8 T-cell receptors. Meanwhile, the CD8 co-receptor of CD8 T-cell would interact with α3. β2M: Beta 2 microglobulin; MHC I: Major histocompatibility complex class I; CD8: Cluster of differentiation 8.