ALFA (Allergy Lateral Flow Assay) is a rapid test for the determination of allergen specific Immunoglobulin E (sIgE) in human serum, plasma or whole blood by Dr. Fooke
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- With the help of a special scanner system, the LFA (Lateral Flow Assay) Reader, the result can be converted to a semi-quantitative one to replace the traditional skin prick test which requires experience in operation and interpretation and may induce anaphylaxis. The LFA Reader is a mobile measuring device for the quantitative evaluation and documentation of ALFA. The test result is stated in Units (U/mL) and classes, according to the RAST classes. For documentation the results can be printed, stored on an internal memory of the LFA Reader or exported. (Download: Flyer LFA Reader)
- A Better Choice to Skin Prick Test which covers the most common allergens in Hong Kong, Macau, and southern China with just one sample of whole blood. Commonly use of antihistamine will also make skin prick test unusable.
- It tells whether the patient is Sensitized or not in 20 minutes
- ALFA consist of one basis unit – the ALFA Basis Set – in combination with different, freely selectable allergen solutions, as single or mixed allergens (Screens) or as recombinant or native, highly purified allergens. ALFA Basis Set is available as single- (REF 1800010) and eight-strip cassette (REF 184000) – plus variable allergen solutions. (Download: ALFA sIgE flyer)
Ten Advantages of ALFA sIgE test
- Fast – Test result is available in 20 minutes. It can be presented to patient immediately at clinic
- No sample pre-treatment is required – whole blood, serum, and plasma are applicable.
- User friendly – only TWO steps procedure: add the blood, followed by adding allergen(s). No experience and expertise is required to perform the test.
- Safe – no risk for triggering allergic symptoms and anaphylaxis
- Good sensitivity and specificity – excellent correlation with skin prick test and other laboratory test methods for specific IgE
- Result is not influenced by pre-medication – patient does not need to stop anti-allergy medication for the test
- Suitable for all allergic patients – usable for patients with rhinitis, asthma, and skin allergies and no worry for false positive result from dermatographism
- Satisfy different allergy diagnosis needs – dedicated screening panels for perennial, seasonal and food allergens in southern China as well as hundreds of other inhalant and food allergens, as well as specific allergen components.
- Semi-quantitative evaluation – measuring results in Units corresponding serum IgE test with classes allocation analogous to RAST
- Documentation of results – by printout with bundled ALF reader. Result can be stored in SD card and/or export to PC
ALFA Test Procedures
ALFA consists of a uniform test device – the ALFA Basis Set – in combination with several arbitrary single- or allergen-mixture-solutions (screens). The sample (serum, plasma or whole blood) is transferred onto the sample application point of the Basis Set. Immediately afterwards the desired allergen solution is added. After 20 minutes the result can be evaluated based on the test line (T). The functionality of the test is evaluated based on the control line (C).
- The patient´s sample is transferred to the sample application window of the Basis Set, (S) followed by adding the desired allergen solution. During incubation of 15-20 min, the mixture is driven through the device by capillary flow.
- The allergen specific IgE of the sample binds specifically to its corresponding allergens of the allergen solution. The labelled allergens are retained at the test line (T) by a capture molecule. At the same time, the sIgE bound to the allergen is bound by an antibody coupled to coloured particles (conjugate).
- The intensity of the color reaction at the test line is proportional to the amount of immune complexes consisting of ligand tagged allergens, sIgE, and IgE specific conjugate. The signal intensity ranges from faintly pink (low titer of sIgE) to dark ruby (high titer of sIgE).
- Access conjugate, which is not bound at the test line, will also form a dark ruby control line (C) to show workability of the test after the 20 min of incubation.
Sensitivity, speciﬁcity and agreement of ALFA against SPT
Performance against ImmunoCAP
Indoor inhalants allergen panel for ALFA (cover 80% to 90% of common respiratory allergens in Hong Kong)
Pediatric allergen panel for Hong Kong
Seasonal inhalants allergen panel for ALFA
Other selectable allergens (match those for skin prick test)
- Different house dust mites
- Animal hairs / danders
- Pollens (tree / weed / grass)
- Milk & Derivatives
- Egg & Fractions
- Fruits & vegetables
- Nuts & Seeds
- Others (Download: list of allergens and the current list of recombinant or native, highly purified allergens)
- Various recombinant allergens components (for research purpose)
- Special occupational allergens like latex for health workers
- The normal serum IgE concentration is age dependent with a peak at the age of 6-15 years. The occurrence of allergen specific IgE is often accompanied by increased titers of total IgE in the blood of the patients.
- IgE concentrations are determined in international units per millilitre (IU/mL) whereat 1 IU/mL corresponds to 2.4 ng of IgE.
- Highest IgE concentrations occur in patients with atopic dermatitis in which they often reach levels of 50.000 IU/mL.
- Moreover, increased titers of IgE can be observed e.g. in patients with parasitic diseases.
- Deviations to the normal values have also been described in patients with certain autoimmune disorders
The ALFA Total IgE Test
ALFA (Allergy Lateral Flow Assay) Total IgE is a rapid assay for the qualitative determination of total IgE in human serum, plasma or whole blood. ALFA Total IgE is designed as a screening test which allows a fast and easy detection of increased and highly increased Total IgE titers. Furthermore the test can be used in laboratories as validity check and confirmatory test, respectively. (Download: Flyer ALFA Total IgE) ALFA Total IgE consists of a test device – the ALFA Total IgE Basis Set – in combination with an Anti-IgE Solution. To perform the test the patient’s sample is transferred to the sample application point of the Basis Set. Immediately afterwards the Anti-IgE Solution is applied. During incubation time of 25-30 min the liquid is driven through the device by capillary flow. For interpretation of the result, the number of visible test lines and their intensity is assessed by an evaluation card (Download: instruction for use ALFA Total IgE) or with the LFA Reader in U/ml.
- ALFA (Allergy Lateral Flow Assay) Total IgE is a rapid assay for the qualitative determination of total IgE in human serum, plasma or whole blood.
- ALFA Total IgE is designed as a screening test which allows a fast and easy detection of increased and highly increased Total IgE titers.
- Furthermore the test can be used in laboratories as validity check and confirmatory test, respectively
- ALFA Total IgE consists of a test device – the ALFA Total IgE Basis Set – in combination with an Anti-IgE Solution.
Principle of ALFA Total IgE Test
Immediately after application of the sample (serum, plasma or whole blood) onto the sample application point of the Basis Set, the Anti-IgE Solution is applied. After 25-30 min the result of the test line (T) can be assessed by the help of an evaluation card. The functionality of the test is determined by the control line (C).
ALFA Total IgE Evaluation Card
Good agreement to Total IgE test (EIA method) in laboratory
Type I Hypersensitivity & sIgE
The term allergy is often used for type I hypersensitivity reactions (immediate type reactions), whose symptoms generally occur within 30-60 min after contact with the allergen. The most frequent symptoms are: hay fever (rhinitis), conjunctivitis, hives (urticaria), allergic asthma and as the most dangerous manifestation anaphylaxis (the anaphylactic shock). The allergens causing type I hypersensitivity reactions are mostly proteins derived from the natural environment e.g. plant pollen, animal hair, food, mites and insect venoms. The characteristic of type I allergies is the involvement of allergen specific immuno-globulins (antibodies) of class E (sIgE). Hence, the detection of sIgE is an important tool of modern allergy diagnostics.