Comparison of β2-microglobulin serum level between Alzheimer's patients, cognitive healthy and mild cognitive impaired individuals

Background: Several studies performed in the last years on the brain, showed that beta2-microglobulin (beta 2m) and MHC can act independently of their canonical immune function to regulate normal brain development, synaptic plasticity and behaviour. Increased systemic levels of soluble beta 2m have been implicated in cognitive impairments like that associated with chronic haemodialysis, or aortic valve replacement. Increased soluble beta 2m has also been detected in the cerebral spinal fluid (CSF) of patients with HIV-associated dementia and Alzheimer's disease (AD). Objective: To compare plasma beta 2m levels in healthy subjects and subjects with dementia or cognitive impairment. Methods: We measured the concentration of beta 2m in a cohort of 245 individuals and compared sex matched, cognitive healthy individuals. Results: We found higher levels of beta 2m in AD patients compared to non-AD MCI and healthy controls (2063 ng/mL +/- 852 versus 1613 +/- 503 and 1832 +/- 382 ng/mL, p<0.001 and <0.033, respectively), while there was no difference between mild cognitive impairment (MCI) and healthy controls (p>0.05). Conclusions: Our data confirm that beta 2m could play a role in AD. However, a replication study in an independent cohort would be necessary to confirm our preliminary results.