This month’s editor’s feature focuses on the Johns Hopkins DACI Reference Laboratory. DACI is an acronym for Dermatology, Allergy and Clinical Immunology (pronounced “day’-see”). The DACI Laboratory is located on the 1st floor of the JHAAC and is directed by Robert G. Hamilton, Ph.D., D.ABMLI, with N. Franklin Adkinson, Jr., M.D., serving as the Medical Director. The laboratory staff includes Jack Wisenauer and Charles Bronzert as laboratory technologists and Michael Ludden and Lynda Miller in the business office.
The DACI Reference Laboratory is a federally licensed clinical facility that began operation in 1982. It provides comprehensive, high quality diagnostic allergy and immunology testing to patients throughout North America with asthma, allergic and other immunologic disorders. The DACI Laboratory operates as an integral component of the Johns Hopkins University clinical laboratory network that is operated by the Departments of Medicine and Pathology.
The laboratory moved from Good Samaritan Hospital to its current location in the Johns Hopkins Asthma & Allergy Center in 1989. One of the unique features of the DACI laboratory is the longevity of its employees. Jack Wisenauer and Charlie Bronzert have been working with Dr. Hamilton for about 23 years. Carol Schatz retired a few years ago and was one of the laboratory’s long-term administrative employees, and Lynda Miller, although she has not always worked in DACI, has been with the division for many years.
The DACI Laboratory offers an extensive menu of laboratory tests that include total and allergen-specific IgE measurements to approximately 200 pollen, epidermal, mold spore, mite, food, drug, venom, and occupational allergen specificities. The laboratory specializes in Hymenoptera (insect sting) venom specific IgE and IgG antibody measurements. In addition, the DACI Laboratory performs hypersensitivity pneumonitis precipitin panels, serum cotinine, and quantitative environmental allergen measurements (dust mite, cat, dog, cockroach, mouse, rat, and mold).
I asked Dr. Hamilton if I could visit the laboratory, and here is our interview:
What is the most unusual request you have received for analysis in the DACI laboratory?
I had the pleasure of serving as a consultant to the U.S. Congress on methods of environmental sampling in the anthrax investigation, although none of the actual anthrax testing was done in the DACI laboratory.
Currently, one of the more unique projects is working in conjunction with George Washington University staff and the Gates Foundation on evaluating the immunogenicity of several new therapeutic vaccines for eliminating hookworm from developing past the larval stage in infected humans. The clinical studies are being done in Brazil where hookworm is endemic.
Another unique area of testing involves the assessment of patients on omalizumab who fail to show clinical benefit. We have been working on analytical methods for measuring free IgE circulating in the blood of individuals who have received Omalizumab. Investigations are continuing to see if the free IgE levels can provide insight into the reasons why some patients fail to receive clinical benefit from anti-IgE therapy.
We have a variety of investigations ongoing that involve evaluating novel drugs for their potential immunogenicity in humans. These projects have encompassed the development of assay methods to measure IgE and IgG antibodies to a number of carbohydrates, DNA aptimers, and protein based drugs that are pending FDA licensing.
Possibly more relevant to the allergy community is the serological testing that we perform asa core laboratory as part of Phase III clinical trials of new therapeutic allergen extracts. Our analyses focus on allergen-specific serum IgE and IgG antibody measurements in subjects over the course of immunotherapy clinical studies involving subcutaneous, oral and sublingual administration of allergen.
What kinds of services do you offer for assessing mold or building contamination?
Assessment of mold in an indoor environment is a challenge. First, we provide the allergist with a diagnostic test to confirm sensitization (IgE antibody positivity) to any of the known clinically relevant molds. Secondly, we perform a viable mold spore analysis that is used to identify indoor environments that have high levels of mold spores. A surface dust sample is collected from the environment and plated out on Sabourunds medium containing antibiotics. We know of no defined level of mold spores that correlates perfectly with the presence of allergic disease to a particular mold. So it is difficult to apply these measurements in judging the presence of mold contamination in an indoor environment. However in certain cases of litigation, this viable mold spore analysis can be useful.
What makes DACI a unique testing facility?
The DACI Laboratory provides the complete repertoire of allergen specificities for IgE antibody detection. Many laboratories provide only the major allergenic specificities. Additionally, we provide a quantitative measure of selected allergen-specific IgE levels (when requested) that are typically off the scale and reported by other laboratories as >100 kUa/L.
The DACI Laboratory performs some unique testing for Hymenoptera venom allergic patients. More specifically, we perform a venom inhibition analysis to examine possible cross-reactivity of IgE antibodies between yellow jacket and Polistes wasp venom. In certain situations where you want to minimize the number of injections during their venom immunotherapy, if the IgE anti-yellow jacket venom is >95% cross-reactive with Polistes wasp venom, the Polistes venom can be removed from the treatment regimen and the patient only needs to be treated with yellow jacket. About 1/3 of all sensitized individuals fall into this category. Our specialty is the assessment of antibody responses to new drugs or to therapeutic Phase III clinical trials of allergen extracts.
Is there any specialized equipment in the DACI laboratory that sets it apart from other laboratories?
In addition to all the standard immunology based instruments we use for allergy diagnostics, we have a number of research instruments such as a surface plasmon resonance assay system (BiacoreÔ) that examines molecular interactions in real time and the Bioplex system that allows effective cytokine quantification with low volumes of specimen. At present, we are one of only a few laboratories in the USA that performs the microchip based ISAC (immuno-solid-phase allergy chip) for allergen-component-specific IgE detection.
What standards does the DACI laboratory set for other allergy laboratories?
All American clinical laboratories must be federally licensed. To be licensed to perform IgE antibody measurements, laboratories must participate in an external proficiency program. This involves testing masked blood samples for total and specific IgE antibody data. The data are then compared to other laboratories that also participate in the survey as part of a required quality control program. The DACI Laboratory has been distinguished by the fact that it oversees the collection of serum specimens and the interpretation of data for the most widely subscribed proficiency program in the USA that is conducted by the College of American Pathologists. We have had the pleasure of coordinating the diagnostic allergy proficiency survey for the College over the past eight years.
I would like to thank Dr. Hamilton for taking the time for this interview. In parting, he mentioned that one of the funniest things that has happened in the laboratory is a letter they received that is currently framed and hanging on their wall. It is addressed to the DACI Reverence Laboratory. I hope you will visit the laboratory, the staff, and Dr. Hamilton when you are visiting the Asthma & Allergy Center. The DACI Laboratory is located in Room 1A.20.
To get more information on the DACI lab and its services, please visit our Website at http://www.hopkinsmedicine.org/allergy/daci/index.html or call 800/344-3224 (DACI) or 410/550-2029, Monday thru Friday, from 8:30 a.m. to 5 p.m. (EST).