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Vol. 6 No. 2 - April 2000

Allergy - Manifestation of Environmental Nuances

By: Vini Tandon

Our daily life is a continuous interaction between our body and the physical milieu enveloping us, food we ingest, the plants that grow around us, the animals and their products we come across knowingly or unknowingly, the things we contact every moment, whether sleeping or relaxing or travelling or preoccupied in our profession. However, nature has provided an innate ability to each one of us to recognize SELF and NONSELF, and the ability to discriminate between harmful and non-harmful things amongst the non-self. Body defenses are always on an alert and work constantly round the clock sensing, suspecting and reacting to these environmental non-self things. Once the sensors sense or even suspect the peculiar non-self surrounding, whether touched, ingested or inhaled, the body initiates an involuntary cascading reaction using all or one of its defense mechanisms and produces some recognizable response or symptoms to avoid or remove the non- self substances. The response may be a non-specific inflammatory response to the irritant or it may be a specific immunological response produced by a specific antigen antibody reaction triggering either one of the four recognized prototype hypersensitivity reactions, commonly grouped as allergic reactions. Sometimes the reaction is directed not only against the labeled and identified allergen, but also, against the other antigens sharing a similar protein epitope, thus cross reacting with the preformed antibodies.

Allergy is a broad-spectrum common-mean term, literally meaning "changed reactivity" and scientifically synonymous with the Type I Hypersensitivity reaction. The other type of Hypersensitivity reactions (Type II, III, IV) are just pedagogical categorization attempted b) immunlogists to increase the understanding of different immune reactions which could be provoked b) many antigenes. In practice these types do not occur in isolation from each other and mostly overlap.

Our environment abounds with uncountable allergens- (known substances capable of triggering specific antigen antibody hypersensitivity reaction merely by contact or inhalation or ingestion) and many more haptens (substance capable of inducing hypersensitivity reaction not by themselves alone but only after combining with some non-allergens). Each individual is unique and so is his or her response to these environmental irritants. The consequent allergic reaction may produce symptoms in one or more or all of the systems which we all encounter at one or the other time in our life.

The skin is the most common organ which comes in contact with these irritants and produce atopic dermatitis (eczema) or in response to a systemic irritants produce urticaria (hives). The other common organs affected are the eye and nose producing rhino-conjunctivitis and bouts of sneezing etc. Major insult and irritation of the environmental allergens is borne by the respiratory system which revolts and cries for help producing wheezing and asthma- now a major health problem of our country. In our greed and ignorance, we tend to insult our another lifeline system, the gastro-intestinal system that again produces the stereotype reaction to these allergens might produce a Type IV hypersensitivity reaction of anaphylaxis, which may become fatal if not controlled in time.

These above mentioned symptoms may be an outcome exposure to the various grass, weed and tree pollens which float in the air we inhale, producing seasonal symptoms in many individuals, which might be relieved or aggravated in different geographical zones depending on the habitat. Another group of irritant is the moulds and yeast, which might be ingested or float in the air we inhale and irritate the exposed systems. The group of allergens available ubiquitously in our environment is in the form of epidermal and animal proteins released as dander's feathers, bird droppings or murine and vertebrate defecates. Of course the list of ingested proteins is as long as one can think and includes almost all proteins derived from the animal kingdom as egg, milk, fish etc and those of the plant kingdom in cereals, fruits, vegetables, spices etc. The venoms of the innumerable insects and reptiles in our environment are another potential under odd and bizarre conditions and surroundings. Sometimes the therapeutic drugs given in good faith may produce hypersensitivity reactions due to the drug compound itself or hapten or the preservative or additive in the drug.

The reaction to the exposure to the allergen depends on the type of reaction triggered, the quantity of allergen exposure and pre-sensitization of the individual to the allergen. At times the response is mild initially and go unnoticed till the sensitization or the allergen dose reach a stage producing grave symptoms and fatal reactions.

Some such allergens are the occupational allergens, which might produce havoc in one's life by its repeated or continuous exposure. The allergen may be a chemical compound or metallic alloy, a plant protein or animal product. The list is inexhaustible and every thing on earth can be included and enlisted.

Many of the common plant derivatives, used in our day to day life at every step from survival to pleasure to relaxation can be the culprits, provoking this unwanted allergic reaction. The morbidity due to these allergic disorders is very high and most manifestations are misunderstood due to poor degree of suspicion and thus misdiagnosed and maltreated. It is important to rightly recognize them, and avoid contact with the specific agents, if possible, to reduce daily morbidity.

One may be surprised that latex products made from the sap of Hevea braziliensis is one of the latest recognized allergens inflicting its havoc in our sophisticated lifestyle obsessed by concerns for style, sanitation and spread of the dreaded AIDS virus. This goes mostly unnoticed as the symptoms may be mild and simulate many non-specific reaction, but at times the reaction is grave or may be fatal. It may be an instant reaction or a delayed hypersensitivity depending upon the sensitivity of the individual. The reason for this is the lack of awareness amongst the users, who might get caught totally unwarranted at wrong corners and fail to link the symptoms to latex.

Are we aware of the wide use of latex products in our day to day life? Perhaps no. Well, latex is used in small things like balloons and toys, baby-bottle nipple and pacifiers, condoms and diaphragms, tyres and tubes, garden hoses and LPG connectors. Another set of people in contact with latex are the medical and paramedical staff wearing gloves, and patients wearing stretchable bandages and medical tapes or those in critical operative and post-operative care with anaesthetic tubing's, ventilation bags and intravenous lines. Even the small day to day things like the socks, the shoe laces and other undergarments have elastic made from latex.

The sensitivity to these, varies from individual to individual and also on the degree of exposure. Typically, the more contact one has with latex, the more sensitive he or she may become.

The problem is ubiquitous and perhaps linked to an epitope in the rubber protein. The resemblance to these epitopes is observed in many other plant products and all those who are sensitive to latex may display cross reactivity to these products. It has been observed that these latex-sensitive people display potentially life-threatening reaction to specific foods especially bananas, avocados, water chestnuts and even peanuts.

The best way to survive and avoid the unwanted reactions is to rightly recognize the culprit and to avoid it as far as possible using other alternative things. The next best is to recognize the reaction and take proper medication to limit the reaction. As and when the facility for desensitization will become available, it may be tried. But awareness is the KEYWORD. Take care for you might also be an innocent unsuspected victim.

Dr. (Ms.) Vini Tandon, M.D. (Pathology), is a medical scientist at 1/104, VishwasKhand, Gomti Nagar, Lucknow

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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