?2-microglobulin (B2M) is a principal component of the Major Histocompatibility Complex (MHC) class I molecule, a ternary membrane protein complex that displays fragments derived from proteolyzed cytosolic proteins on the surface of cells for recognition by the surveillance immune system . As an integral component of the MHC class I complex, ?2-microglobulin plays a critically important role in immune system function . It has important relevance to cancer biology research; for example, research studies have shown that nearly one-third of diffuse large B cell lymphomas contain mutations that inactivate ?2-microglobulin gene function, thereby allowing tumor cells to escape immune detection . In addition, ?2-microglobulin has been identified as an amyloid preprotein with collagen-binding affinity ; its accumulation in osteoarthritic lesions of long-term dialysis patients is reportedly a contributing factor to the condition known as amyloid osteoarthropathy .