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Next-level testing for allergy, autoimmune disease

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Amy Carpenter Aquino

March 2022—Recent years have seen new releases in allergy and autoimmune disease testing that move the fields forward.

“On average we’re looking at six to 10 years of a patient going through the process of seeing specialist after specialist and finally reaching a diagnosis,” Veena Joy, MSc, PhD, Thermo Fisher clinical affairs manager of autoimmunity-immunodiagnostics, says of autoimmune disease. “Autoimmune diseases have low incidence and prevalence rates, so the specificity of the assay is critical.”

Joy

Thermo Fisher’s EliA SmDP-S assay to aid in the diagnosis of systemic lupus erythematosus, cleared by the FDA last year, was designed and developed to enhance specificity without compromising the sensitivity, Joy says. “We revamped our existing EliA SmDP assay to have increased specificity,” which helps physicians differentiate lupus from mixed connective tissue disease, “providing a higher degree of diagnostic confidence.”

The SmD3 peptide has been identified as the most specific Sm antigen for SLE. The EliA SmDP-S, Joy says, combines a synthetic version of this SLE-specific SmD3 peptide with an advanced coating technique that optimizes the binding of the SmD3 peptide antigen, “further improving specificity and therefore supporting a more precise diagnosis.”

Werfen’s next-generation Aptiva system was also cleared last year, with the first U.S. implementation to get underway soon, says Bill Manchester, vice president of worldwide marketing and service for Werfen Autoimmunity.

With the new system, he says, Werfen is combining biomarkers to address a disease state. For connective tissue disease, for example, “we can have an essential panel with multiple tests at one time. The same concept applies to other disease states, such as myositis, celiac disease, vasculitis, or antiphospholipid syndrome. We can generate several results—for example, 11 for the CTD Essential panel—from one cartridge instead of one at a time,” Manchester says.

New biomarkers that are included in the Aptiva menu will help close “the seronegative gap,” he says, but Werfen will do it in an automated fashion by combining it with its other existing markers. “So we’re moving forward with multiple tests in one cartridge but also using our chemiluminescence technology”—the Bio-Flash platform—“to push it forward.”

Werfen received FDA clearance in 2021 for the Aptiva Celiac Disease IgA and IgG assays and the CE mark for the Aptiva CTD Essential panel. “We’re marching forward with Aptiva assays for APS [antiphospholipid syndrome], rheumatoid arthritis, irritable bowel syndrome, myositis, vasculitis as well as autoimmune liver disease. We are expecting regulatory approvals throughout this year and beyond,” Manchester says.

With its Quanta Link data management system, he adds, they’re able to tie together the different technologies—indirect immunofluorescence (including Nova View), ELISA, chemiluminescence, and now Aptiva, the particle-based multianalyte technology (PMAT). “Consequently, we are able to deliver different technologies including immunofluorescence, the gold standard, in addition to chemiluminescence and PMAT. We are convinced that particle-based assays such as Bio-Flash and Aptiva represent the future in autoimmune testing.”

Falcetano

In allergy testing, allergen components are where the interest is, says Gary Falcetano, PA-C, Thermo Fisher’s clinical affairs manager for allergy-immunodiagnostics. The FDA in 2020 cleared the ImmunoCap specific IgE allergen component test for alpha-gal, and in 2019 it cleared the allergen component tests for stinging insects and pet allergen components. “Our allergists continue to ask for additional components and additional help in understanding the available components and how they can best use them to serve patients,” Falcetano says.

“Where the whole allergen extracts are great for sensitivity,” he says, “the components allow us to be more precise in the diagnosis.” Clinical history is always key to diagnosis, he adds, “but the allergen components take it to the next level.”

Thermo Fisher will continue to bring components before the FDA, he says, but, like so much else in laboratories, expanding menus has been secondary to SARS-CoV-2. “Everything tends to take a back seat to COVID testing, as it should,” he says, noting the staff shortage that predated the pandemic and is now acute.

Joshua Bornhorst, PhD, DABCC, Mayo Clinic consultant and assistant professor and co-director of clinical immunoassay laboratories, which includes allergy testing, presented a session at the AACC annual meeting last year on food allergy testing, where he called specific versus component IgE antibody testing “one of the current frontiers” of antibody IgE testing.

“When we talk about specific, we’re talking about the mix of all allergenic and nonallergenic proteins in an extract,” he said in the session. “So in some ways the title ‘specific’ antibody testing is a misnomer. It’s not just for antibodies against one protein, but rather a group of proteins extracted from that allergen. You don’t know which protein is involved because there are multiple proteins in that mixture. It’s called specific, though, because it is a specific extract of something.”

The next level is component allergen IgE antibody testing. “Now you can take individual components from that specific mixture, once you’ve identified them as the proteins or the chemicals that cause an allergic reaction,” he said. In the case of proteins, one can make a homogeneous mixture of purified or recombinant component, bind it to the matrix, and assess the ability to look for the antibodies against that specific component.

“These two can work hand in hand,” Dr. Bornhorst said.

The most common traditional multiallergen antibody panels are multispecific allergen panels. “You can take groupings of certain foods or epithelial allergens and run either combined assays or multiple specific assays for all of them. You can create a targeted panel”—food, food/nut, epithelia panels, for example—“to evaluate a set of clinical symptoms,” he said. It’s a more rapid approach to screening, it can rule out sensitization to multiple related allergens, and it offers flexibility in designing the panels in accordance with the preferences of clinicians. However, a positive result in combined assays does not identify specific allergen sensitization; thus it doesn’t always correlate with individual allergen testing. Even with multiple individual specific panels, he said, there is a lack of standardization among clinicians in the testing performed.

Common examples of existing or soon to be released component antibody panels are peanut, expanded nut, venom, egg, and animal dander and allergenic pet.

Egg component antibody panels are isolated components found in eggs, he said. There is a whole egg specific test that is a whole egg extract, and an egg white allergen-specific test, which is egg white extract. There is egg yolk, too. “And within those specific tests there are different components,” Dr. Bornhorst said. “We do have assays for two of those components: ovomucoid and ovalbumin.” Starting with whole egg, one can identify that the patient has an allergen to egg white and then dissect that further through the component test. “The difference between ovomucoid and ovalbumin is that ovalbumin is unstable,” he said, “so things that are highly processed or cooked—if you have an ovalbumin allergy—should be relatively safe. If you have an ovomucoid, cooking the egg won’t affect your allergic response.”

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