Microarray Immunosignature System Diagnoses Cancer

This immunosignature approach leverages the response of antibodies to disease-related changes, as well as the inherent signal amplification associated with antigen-stimulated B-cell proliferation. This would be a substantial improvement over highly specific bioassays that can only test for a single biomarker antibody, often with substantial misidentification or inadequate sensitivity.

Scientists at the Arizona State University (Tempe, AZ, USA) analyzed serum samples from 20 samples each from five cancer patient cohorts, along with 20 non-cancer patients to establish reference immunosignatures. Once reference immunosignatures were established, the technique was tested in blind evaluation of 120 independent samples covering the same diseases.

The technique relies on a microarray consisting of thousands of random sequence peptides, imprinted on a glass slide. The peptides used were 20 unit amino acid chains, randomly composed. When less than a microliter of serum is spread across the microarray, antibodies in the blood selectively bind with individual peptides, forming a portrait of immune activity resulting in an immunosignature. The microarrays are scanned at 10-μm resolution at 647-nm wavelength by a High-Resolution Microarray Scanner (Agilent Technologies; Santa Clara, CA, USA) using high laser power and 70% gain for the photomultiplier tube.

To further assess the diagnostic power of immunosignaturing, over 1,500 historical samples comprising 14 different diseases, including 12 cancers were tested. In this case, 75% of the samples were used in the training phase and the remaining 25% subjected to blind testing. Remarkably, an average diagnostic accuracy of over 98% was achieved, demonstrating the suitability of immunosignaturing for the simultaneous classification of multiple diseases. In another trial, 14 separate diseases were distinguished from one another as well as from healthy controls, through immunosignatures. Among the cancers tested were three different stages of breast cancer, four different brain cancers, two pancreatic diseases, ovarian cancer and two different blood cancers.

The presence of 10,000 peptides on each microarray chip allows for enhanced sensitivity, owing to the large number of different possible signals elicited. The technology is also highly flexible in terms of handling and processing. A dried sample of blood, collected on filter paper and mailed to a study facility can be used to generate an immunosignature, permitting frequent health monitoring at low cost. The study was published on June 23, 2014, in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

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Arizona State University
Agilent Technologies