Diagnosing and understanding different types of allergy

By Priya Chetty on July 30, 2016

The term allergy was first given by von Pirquet in 1906 to an immune response that is not protective to the host (Nieminen 2009). The purpose of the immune system is to generate antibodies in response to pathogens or foreign matter. Immune system comprises different cells which fight against infection using different mechanisms. Some of the cells which produce immune response are; B cells, T cells and phagocytes. Wherein, the B cells produce antibodies in the bloodstream by giving rise to plasma cells. T cells have surface receptors that mimic antibody or immunoglobulin (Ig). It is a form of glycoprotein, characterized into five types (IgG, IgM, IgA, IgE and IgD). And phagocytes swallow the invaded particle owing to their large size.  The antibody IgE is responsible for allergic responses (Works 2003).

Sensitization of IgE occurs when allergen-specific IgE antibodies bind to IgE receptors that are present on basophils and mast cells (See figure below). The second contact with the same allergen leads to its binding to the antigenic determinant site of IgE –Fab (Works 2003). Cross-linking of IgE is necessary for producing an effect, which occurs when two or more IgE bind to the mast cells. Thus, activation of mast cells generates many chemicals, histamine, proteoglycans, serotonin and serine protease; as a result, these on linking to their specific receptors fabricate an immune response. Furthermore, this immune reaction leads to inflammation, redness along with other allergic symptoms (Elshemy et al. 2013)

Demonstrates the IgE mediated response to allergy (Elshemy et al. 2013)
Demonstrates the IgE mediated allergic response (Elshemy et al. 2013)

Diagnosing and treating allergies from food

Children are more prone to allergies from food wherein the symptoms may show up instantly (Sampson et al. 2014). Symptoms of the allergy include vomiting, stomach cramps, dizziness, wheezing, cough, pale colouring of skin and anaphylaxis (Sampson et al. 2014). Common food allergens are milk, wheat, peanuts, tree nuts, soy, eggs, sesame or mustard seeds and fish.

Skin-prick test is where a liquid with the food allergen is allowed to seep into the skin and the results show up in 20 minutes (Garfield & Lowell 2013). The reaction to the allergen gives a small red bump similar to a mosquito bite. Blood tests to investigate and evaluate the presence of IgE in the blood sample is another diagnosis (Garfield & Lowell 2013). In terms of treatment, Epinephrine (adrenaline) injections along with anti-histamine medications are essential when symptoms are serious (Garfield & Lowell 2013) which help in managing critical symptoms.

Symptoms of allergy from environmental elements

Environmental allergens include pollens from trees, weeds, dust mites present in household beddings and carpets, animal skin flakes, saliva or urine that combine with dust and spores of molds (Prasad 2013). Symptoms of this allergy include sneezing, coughing, runny or stuffy nose, itchiness and redness in the eyes and nose. Furthermore, shortness of breath, tightness in chest, wheezing, which are triggers to asthma are commonly evident (Prasad 2013).  Most common diagnostic tools include skin prick test, blood test and allergy component test. Medical treatments include antihistamines, decongestants for itchiness and corticosteroids for tenderness in nose and allergy shots that directs the immune system tolerance to further exposure (Singh & Kumar 2003). Furthermore, allergy shots are injected under the skin, subcutaneous immunotherapy or administered under the tongue in the form of tablets or drops and sublingual immunotherapy (Elshemy et al. 2013).

Allergic reactions from medicines

Medicine or drug allergies can be caused by pills like antibiotics, injectables or liquid syrups forms (Nieminen 2009). Though the body might not react to the medicine initially as it prepares itself but next time the symptoms may arise. Antibodies mainly penicillin or those with sulfa components are mostly seen to produce allergic effects (Nieminen 2009). The reactions that follow can be itching, swelling or rashes on the skin, shortness of breath, vomiting, dizziness and worse anaphylaxis (Nieminen 2009).

The primary diagnosis is through general examination after the intake of the drug. Further, a skin-prick test is done by inducing suspected drug allergen can be performed (Allergist 2014). Oral drug challenge under proper supervision and blood tests in case of delayed symptoms can be relevant. Dress syndrome can be diagnosed through a blood test, where multiple organs are expected to be affected by the drug rash (Allergist 2014). Treatments to drug allergies involve antihistamines, corticosteroids or anti-inflammatory non-steroidal drugs to reduce swelling and irritation. In the case of anaphylaxis, adrenaline is injected to manage the blood pressure and breath are required (Elshemy et al. 2013).

Allergies from household chemicals

A person can be found allergic to different chemicals like detergents, preservatives, tattoo ink and black henna, pesticides, sunscreens, formaldehyde, rubber, nickel or other metals, dyes and cleaners. Symptoms include hives, red patchy skin, sun sensitivity, dry/scaly skin, skin blisters or burning sensation (Orivuori 2015).

Hives are itchy rashes on the skin that may appear on any part, especially the one in contact with the chemical allergen. These rashes appear and fade away in a period of time depending on the sensitivity towards the allergen (Allergist 2014). Anti-inflammatory drugs are generally given to treat chemical allergy (Allergist 2014).

Further reading

  • Allergist, 2014. Allergies _ Symptoms & Treatment _ ACAAI.
  • Elshemy, A., Elshemy, A. & Abobakr, M., 2013. Journal of scientific & innovative research. , 2(1).
  • Garfield, A.S. & Lowell, B.B., 2013. Was it something i ate? Cell Metabolism, 18(6), pp.769–770.
  • Nieminen, K., 2009. Immunomodulation of allergic immune response during specific immunotherapy,
  • Orivuori, L., 2015. The Development of Immune Responses and Allergy in Children from Farming and Non-farming Environments, Available at: https://helda.helsinki.fi/handle/10138/156058.
  • Pawankar, R., 2014. Allergic diseases and asthma: a global public health concern and a call to action. World Allergy Organization Journal, 7(1), p.12. Available at: http://www.waojournal.org/content/7/1/12.
  • Prasad, R.K., 2013. Allergy Situation in India : What is Being Done ? Indian J Chest Dis Allied Sci, (55), pp.7–8.
  • Sampson, H.A. et al., 2014. Food allergy: A practice parameter update – 2014. Journal of Allergy and Clinical Immunology, 134(5), pp.1016–1025.e43.
  • Singh, A.B. & Kumar, P., 2003. Aeroallergens in clinical practice of allergy in India. An overview. Annals of Agriculture and Environmental Medicine, 10(2), pp.131–136.
  • Works, H.I., 2003. Understanding the Immune System How It Works. Health San Francisco, p.63. Available at: http://hdl.handle.net/1805/748.


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