DACI LABORATORY
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.
DACI
STAFF
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).