A technique known as immunosignaturing harnesses the human immune system as an early warning system, which is acutely sensitive to changes in the body that may be indicative of disease.

These immunosignatures are not only strong indicators of presymptomatic illness, but those samples from serum, plasma, saliva and dried blood can yield reliable and highly stable diagnostic results under a variety of conditions.

A team of scientists from Arizona State University (Tempe, AZ, USA) has developed the immunosignaturing technique that uses random sequence arrays of peptides to trawl for antibodies to disease. They demonstrated that a glass slide containing an array of some 10,000 such random sequences, each composed of 20 amino acids, can be used to screen the body's full complement of antibodies, when a single drop of blood is spread over its surface.

When the antibodies present in a sample of blood are splayed over the peptide array, they selectively bind to these peptides with varying degrees of affinity. Once the blood is washed away, a machine-readable image of immune activity is left behind, the immunosignature, potentially providing presymptomatic diagnosis for a broad range of ailments, from infectious diseases to chronic afflictions to varied forms of cancer.

The immune fingerprint thus produced will show thousands of spots fluorescing at different levels, corresponding to antibody activity. Immunosignatures may be registered repeatedly over time and will display characteristic changes following exposure to a pathogen, a vaccine, or any other factor provoking an alteration in antibody activity.

The investigators demonstrated that immunosignatures remain stable over time and largely unaffected by variance in methods of collection. Such versatility could open the door to the use of vast archival material, for example, samples from prior studies and disease epidemics. It would also allow immunosignaturing to be broadly applied as a diagnostic for routine health monitoring, particularly in developing countries.

Human saliva was assessed for its ability to provide an accurate immunosignature. Although quantities of antibodies of the immunoglobulin G (IgG) variety were low, saliva samples did contain sufficient antibodies of the IgA type to produce a useable immunosignature, making collection of saliva a plausible, noninvasive alternative for sample collection.

Stephen Albert Johnston, PhD the senior author of the study said, "The new data advance the prospects for applying immunosignaturing as a sensitive, low-cost, universal system for assessing health status. Our ultimate goal is to monitor the health of healthy people, so it is crucial we have a technique that is cheap, simple and, as we demonstrate here, robust." The study was published in the March 2012 issue of the journal Clinical and Vaccine Immunology.

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