Allergy diagnosis has become more complicated, due to
the many mechanisms involved in causing symptoms. By
definition an allergy is an immune-mediated
hypersensitivity reaction, which may be mediated by
different immune pathways, e.g. IgE antibodies,
basophils, eosinophils, T-cells, etc. While great
progress has been made in the diagnosis of basophil
mediated allergy (CAST tests), diagnostic resources for
the diagnosis of T-cell mediated allergy has been
severely lacking.Until recently the only diagnostic
testing available for T-cell mediated allergy has been
Patch testing, which has several disadvantages. We have
been researching a workable alternative which would have
increased sensitivity and specificity and could be
performed on blood specimens collected from any site in
South Africa. We are happy to announce that we have
found such an alternative, the MELISA® (Memory
Lymphocyte Immunostimulation Assay) test , a modified
lymphocyte proliferation assay, patented by the MELISA®
Medica foundation in Stockholm, Sweden.
T-CELL MEDIATED ALLERGY
T-cell mediated allergy is a delayed hypersensitivity reaction that often presents with skin or mucosal rashes or eruptions. A variety of skin symptoms may be experienced, e.g. maculopapular rashes, bullous eruptions, urticaria, edema, itching, eczema, etc. Oral lichenoid reactions may also arise from T-cell mediated allergy in the mouth. Pulmonary symptoms and other delayed allergic reactions may also be associated with T-cell mediated allergy.
THE MELISA® TEST PRINCIPLE Citrate blood is
collected from the patient, preferably 30ml in adults
and 15 ml in young children, to obtain sufficient
lymphocytes for testing. Lymphocytes are isolated from
the patient’s blood sample and co-cultivated with
allergen solutions for 5 days. Lymphocyte proliferation
is measured by 3H-Thymidine incorporation and lymhocytes
are also examined morphologically to determine blast
transformation. The test results are usually available
approximately a week after specimen collection, and are
resulted as a stimulation index, which means the
multiple by which the result is higher than the negative
control. An interpretation will also be given, e.g.
negative, border positive and positive. Tests are
performed weekdays, and should reach the laboratory
within 24 hours of venepucture. (Fridays before 12h00).
This test is specifically suited to the diagnosis of
drug allergies, metal allergies, latex allergy and the
diagnosis of delayed hypersensitivity reactions to
foods. |
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ALLERGENS AVAILABLE FOR MELISA® TESTING / ALLERGENE
BESKIKBAAR VIR MELISA® TOETSING: Antibiotic
Allergens / Antibiotika allergene:
- Amoxycillin
- Ampicillin
- Minor / major determinant penicillin mixes /
penissillien mengsels
- Penicillin V and / en G
- Cephalosporin C
- Cefuroxime
- Cefamandole
- Cefazolin
- Tetracycline
- Ciprofloxacin
- Trimethroprim / sulfamethoxasole
Analgesics / Analgetika:
- Aspirin
- Paracetamol
- Diclofenac
- Ibuprofen
- Indomethacin
Anaesthetic agents / Narkosemiddels:
- Lignocain
- Atracurium
- Mivacurium
- Pancuronium
- Rocuronium
- Vecuronium
- Thiopental
- Propofol
Other allergens / Ander allergene:
- Latex / Lateks
- Iodine / Jodium
- Bee venom / Bygif
- Milk/Melk, Wheat/Koring, Soya, Egg/Eier and a
variety of other foodstuffs /en ‘n verskeidenheid
ander voedselsoorte.
Metal allergens / Metaalallergene:
- Berillium
- Cadmium / Kadmium
- Gold / Goud
- Mercury / Kwik (inorganic, thiomerosal, phenyl-
methyl-, ens.)
- Lead / Lood
- Nickel / Nikkel
- Palladium
- Tin
- Titanium
- Aluminium
- Chromium / Chroom
- Cobalt / Kobalt
- Copper / Koper
- Molibdenum / Molibdeen
- Platinum
- Silver / Silwer
- Zink / Sink, etc./ens.
Please contact the laboratory if any other allergens
are required. Nonstandardised assays can also be done
for diverse medications if supplied with the patient
specimen, e.g. other antibiotics and radiocontrast
media. |
