Background: To simultaneously study several biomarkers for Alzheimer disease (AD), we used the xMAP™ technology to develop and evaluate a multiparametric bead-based assay for quantification of β-amyloid(1–42) [Aβ(1–42)], total tau (T-TAU), and hyperphosphorylated tau [P-TAU(181P)] in cerebrospinal fluid (CSF). Methods: We compared the new multianalyte assay format with established ELISA techniques for the same proteins. We then performed a clinical study using CSF samples from patients with AD or mild cognitive impairment with progression to AD, healthy controls, and patients with other neurologic disorders. Results: The INNO-BIA AlzBio3 selectively and specifically measured Aβ(1–42), T-TAU, and P-TAU(181P) in the CSF. The new assay format had intra- and interassay CVs <10% for all analytes, even at low concentrations. The measurement range of the new assay was 3 to 4 logs compared with 1 to 2 logs for ELISAs. By plotting the mean of the values obtained in ELISA and the xMAP technology against the difference, we found that a correction factor could be used to convert xMAP results to ELISA values. The clinical study demonstrated that the new multiparametric assay could accurately distinguish patients with AD from patients with other neurologic disorders or control patients, with the diagnostic accuracy reaching recommended consensus criteria for specificity and sensitivity. Conclusion: The new multiparametric method may be able to replace the corresponding ELISA methods.

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Increased level of NFL is a general feature of MS, indicating continuous axonal damage during the entire course of the disease with the most profound damage during acute relapses. GFAP may serve as a biomarker for disease progression, probably reflecting the increasing rate of astrogliosis.

Our data demonstrate that natalizumab treatment reduces the accumulation of nerve injury in relapsing forms of MS. It is anticipated that highly effective anti-inflammatory treatment can reduce axonal loss, thereby preventing development of permanent neurological disability.

Our study demonstrates an intrathecal production of IL-6 and IL-1 beta in patients with stroke, supporting the notion of localized inflammatory response to acute brain lesion. In addition, the significant correlation between early intrathecal production of IL-6 and the subsequent size of the brain lesion can be used as a prognostic tool, predicting the size of the brain damage before it is possible to accurately visualize it with radiological methods.

The neurofilament protein is a major structural protein of neurons and a marker for axonal damage. The concentrations of the light subunit of the neurofilament triplet protein (NFL) in CSF were significantly increased in patients with relapsing-remitting multiple sclerosis compared with healthy controls (p<0.001). Seventy eight per cent of patients with multiple sclerosis showed increased NFL concentrations. Significant correlations between the NFL concentration in CSF and clinical indices were discerned for disability, exacerbation rate, and time from the start of the previous exacerbation to the time of the lumbar puncture. The results suggest that axonal damage occurs during relapsingremitting multiple sclerosis and that the damage contributes to disability and the appearance of clinical exacerbations. The concentration of NFL in CSF is a potential marker of disease activity in multiple sclerosis and might be useful in future clinical trials of multiple sclerosis. (J Neurol Neurosurg Psychiatry 1998;64:402-404)

CSF NFL differs among different neurodegenerative diseases and is especially high in dementias engaging subcortical brain regions, such as VaD and mixed AD and VaD, but also in frontotemporal dementia. The association of high CSF NFL levels with disease severity and short survival supports the notion that high CSF NFL levels indicate more aggressive disease processes.

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