Immunosignaturing: an accurate, affordable and stable diagnostic


April 23, 2012

Identifying diseases at an early, presymptomatic stage may offer the best chance for establishing proper treatment and improving patient outcomes. A new technique known as immunosignaturing harnesses the human immune system as an early warning sentry – one acutely sensitive to changes in the body that may be harbingers of illness.

Now, Brian Andrew Chase and Barten Legutki, under the guidance of Stephen Albert Johnston, director of the Center for Innovations in Medicine at Arizona State University’s Biodesign Institute have shown that these immunosignatures are not only strong indicators of pre-symptomatic illness, but that samples from serum, plasma, saliva and dried blood can yield reliable and highly stable diagnostic results under a variety of conditions. Download Full Image

As Johnston explains, 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 group’s results recently appeared in the journal Clinical and Vaccine Immunology.

Immunosignaturing uses random sequence arrays of peptides to trawl for antibodies to disease. Previous work has 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 pre-symptomatic 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.

Johnston notes that this approach to diagnosis represents a new paradigm, in that patients will be able to monitor their health with respect to their own particular baseline immune activity, rather than being measured against some standard established for the population as a whole. The method has been tested as a diagnostic for over 20 diseases to date, with each displaying a characteristic portrait.

In addition to accuracy, immunosignaturing provides a particularly versatile platform for disease diagnosis. Unlike many traditional diagnostic exams – for example, the widely used ELISA (for Enzyme-Linked Immunosorbent Assay) – immunosignaturing is not pathogen specific. It therefore permits a general diagnostic screening for multiple disease factors from a single sample. In previous studies, the group demonstrated that immunosignaturing delivers useful diagnostic information for influenza, Alzheimer’s disease, pancreatic diseases and lupus.

In the current study, the group demonstrates 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. Samples of blood or saliva could be mailed to a central processing center.  

Immunosignatures from the same human donor, derived from both serum and plasma were compared in the study, showing good correlation. Two sequential blood draws were collected into either a serum separator tube or a plasma separator tube, to evaluate the influence of clotting factors on the resultant immunosignature. The data shows that plasma and serum produce equivalent immunosignatures. This fact provides flexibility of use for historical samples, which may have been collected using either blood source.

Next, dried blood spots were examined and serum antibodies recovered to produce an immunosignature. Again, a strong correlation of antibody activity was seen in the dried blood vs. fresh serum samples. Rates of protein recovery from dried blood – including functional antibodies – ranged from 78 to 100 percent, in both mouse and human samples. The resulting immunosignatures showed higher fluorescence intensities in the case of fresh serum samples, but the effect was uniform across the array.

Once it was clear that dried samples could be used to produce faithful immunosignatures, the group evaluated the stability of samples stored in a simulated mailing environment, noting that large-scale epidemiological studies and health monitoring via immunosignaturing could be carried out if samples retained potency over time and when exposed to heat.

Samples of dried blood were stored at 25 degrees C or 37.8 degrees C. Immunosignatures remained stable after 2 weeks at the lower temperature. At 37.8 degrees C, samples retained stability overnight, but declined in stability after 2 weeks. As antibodies or immunoglobins are sensitive to bacteria, which may be inadvertently introduced during sample collection or transport, the application of protease inhibitors was subsequently used, and demonstrated an improvement in sample stability. Using dried blood, the team also showed that a characteristic immunosignature could be detected in mice previously infected with influenza, when compared with non-infected controls.

Finally, human saliva was assessed for its ability to provide an accurate immunosignature. Although quantities of antibodies of the 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, non-invasive alternative for sample collection.

The new results indicate that immunosignaturing is not only an inexpensive and sensitive diagnostic technique, but also offers good sample stability over a range of conditions. As a versatile tool for the assessment of presymptomatic illness, immunosignaturing can potentially help alleviate the unsustainable burden to the healthcare system, caused in part by late disease diagnosis followed by exorbitantly costly, (and often ineffective) treatment.

Richard Harth

Science writer, Biodesign Institute at ASU

480-727-0378

Three home runs help ASU softball sweep Stanford


April 23, 2012

The No. 4 Arizona State softball team (39-5, 11-2 Pac-12) saw three home runs in the afternoon finale against the No. 16 Stanford Cardinal (32-16, 6-12 Pac-12), ending with a final score of 7-1.

This weekend’s sweep marked the third-straight home series in which the Devils have swept their opponent - the previous two being Arizona and UCLA. It was also the eighth game in which Arizona State has hit three or more home runs, the most recent being Friday’s game against the Cardinal. Download Full Image

Senior pitcher Hillary Bach is now 19-0 on the year with Sunday’s victory, allowing only three hits and notching three strikeouts.

The Devils wasted no time lighting up the scoreboard in the first inning, with Katelyn Boyd drawing the leadoff walk, Alix Johnson rocketed a two-run homer past both fences in left center. Elizabeth Caporuscio followed later in the frame for her own long-yarder to put ASU up 3-0.

Neither team saw any advance in the score until the top of the fourth. Stanford recorded its only run of the game when Jenna Rich pulled her own long-yarder to make it a 3-1 game.

Boyd then widened the lead in the bottom of the fifth with a two-run shot of her own that pulled the score to 5-1. Pinch runner Kayla Ketchum came around on a passed ball, followed by Talor Haro scoring on a sacrifice groundout for the final score of 7-1.

Teagan Gerhart garners the loss for Stanford, pushing her to 27-10 on the year.

FOLLOW THE SUN DEVILS LIVE
Friday’s game will be on Fox Sports, check TV listings for the channel. Live stats and play-by-play will be available for the Washington series on GameTracker. All links can be found in the sidebar on the Arizona State softball schedule page, which is found here.

UP NEXT:
The Sun Devils travel to Washington April 27-29. Friday’s game will be on Fox Sports, check local listings for the channel. Live stats can be found on the ASU schedule page, here and live video (Saturday and Sunday) here.

VOTE FOR BOYD FOR THE LOWE'S SENIOR CLASS AWARD | Vote Here
Ten NCAA® softball student-athletes who excel both on and off the field were selected as finalists today for the 2012 Lowe's Senior CLASS Award. Katelyn Boyd has been chosen as one of the 2012 finalist. To be eligible for the award, a student-athlete must be classified as an NCAA Division I senior and have notable achievements in four areas of excellence - community, classroom, character and competition. Vote for Katelyn at www.seniorclassaward.com/vote.