Latex Allergy: The history and the Products to Avoid
No allergy has increased so much in the last twenty years as latex allergy. Latex is responsible for immediate reactions (contact urticarial, rhino-conjunctivitis, asthma, and anaphylaxis) and delayed reactions (allergic contact dermatitis). People at risk of sensitization are atopic, people with high exposure (health professionals and the rubber industry), patients who have undergone many operations, people with hand dermatitis. People sensitized with latex can develop reactions of cross food allergies especially with banana, avocado, chestnut and kiwi. The biochemical mechanisms have been partly elucidated with a major role of Hev b 6 in the latex-fruit syndrome and profilins in primary sensitization to grass pollen or trees. A diagnosis is possible thanks to the anamnesis, the skin tests and the search for specific IgE. Measures to reduce latex exposure are the basis of management.
Latex reactions: history
The first report of an immediate allergic reaction probably related to latex dates from 1927: Stern described urticaria and laryngeal edema after dental surgery with latex gloves. Subsequently, delayed type reactions were described many times in 1933, and it was not until the late 1970s that new descriptions of immediate reactions emerged. In 1979, Nutter performs the first prick testing a patient with contact urticaria. In 1984, two intraoperative anaphylaxis reactions related to latex was found. In 1989, many cases involving children with spine bifida were reported, as well as reactions to condom use. Since then, there has been an explosion in the number of reactions. The reasons for this “epidemic” seem multiple: on the one hand the recognition bias; on the other hand the sharp increase in the number of gloves used, resulting in a significant increase in demand and a likely decrease in quality with an increase in the residual protein content in the latex. In 1991, the description of the first case of systemic reaction to banana ingestion in a patient known to be allergic to latex opens the door to latex-fruit syndrome.
Types of reactions
Latex reactions can be divided into several types: local reactions (cutaneous, respiratory) and systemic reactions; reactions by chemical irritation and allergic reactions requiring sensitization, type delay or immediate.
Skin reactions include irritant contact dermatitis, which is not related to hypersensitivity, but to an irritant phenomenon caused by different chemicals used in the medical environment (disinfectants, antiseptic soaps, etc.). These reactions are often augmented by physical factors such as duration of contact, friction mechanisms and moisture (sweating). It is characterized by erythema, pruritus, local edema, and eventually lichenification and crusts.
The dermatitis (eczema), allergic contact is a T-cell-mediated, delayed type (type IV) allergic reaction. It accounts for more than 80% of latex glove reactions and, although generally mild and easily preventable, it causes significant discomfort with repercussions on the quality of life. In general, the sensitization is directed not against the proteins of the latex but against antioxidants or accelerators of rubber vulcanization. The lesion is in the form of erythema, vesicles in the acute phase, then lichenification. It is usually located at the point of contact, but remote extensions are possible. It usually occurs between 48 and 72 hours after exposure.
The immediate reactions are related to the production of IgE against the latex proteins. They range from local reactions contact urticaria, allergic rhino-conjunctivitis, bronchial asthma to all stages of systemic anaphylaxis.
If 240 peptides could be identified in the latex, only about 60 are recognized by the IgE of patients allergic to latex; twelve have been clearly recognized as clinically important allergens by the International Nomenclature Committee of Allergen. They are listed in Table 1 with their biochemical function and importance. As mentioned earlier the amount of these allergens varies widely between products sold. Note that in hard and dry rubber objects (tires, etc.), the amount of protein is very low due to a manufacturing process involving very high temperatures denaturing proteins and that are probably not involved in allergies.
The diagnosis of latex allergy begins with a precise history of the type of reaction, the temporal relationship with latex exposure, the importance of exposure and the risk factors. Tests in search of hypersensitivity are then performed. For skin tests (prick tests, intradermoreaction), the use of untreated latex extract allows to find the largest range of allergens with reproducible results. These tests, performed at the recommended concentrations, in principle do not trigger a systemic reaction and have good sensitivity and specificity. For the search for specific IgEin the blood, several companies have developed tests with a sensitivity of 70-80% and a specificity of 90-97%. In case of discrepancy between the anamnesis and the search for hypersensitivity, it can be realized, either an observation at the workplace or nasal or bronchial provocation tests, but which is still poorly codified.
Since the first description in 1991 of a case of systemic reaction to banana ingestion in a patient known to be allergic to latex, the relationship between latex reactions and those too many foods has been documented. It is estimated that 21 to 58% of allergy sufferers have food reactions especially to fruits and that, conversely, the risk of developing a latex allergy in case of allergy to avocado banana chestnut group is increased by 24 times. The type of reaction represents the full range of anaphylaxis (from simple oral pruritus to shock).
The hypothesis is that of IgE which recognize similar epitopes on proteins most often homologous (phylogenetically close or with structures conserved during evolution). Table 2 presents a list of foods involved with the level of evidence for their cross-reactivity with latex. The allergens involved are defense proteins such as chitinases and glucanases or structural proteins such as profilines. The chitinases class I banana, avocado, chestnut and papaya contain a portion that intersects with hevein, major allergen latex. The profilinesare frequently called pan-allergens because of their presence in many types of pollen of various plant groups (grasses, trees, etc.) and in many plant foods. It seems important to be able to differentiate sensitized patients to food and latex from those sensitized to pollen. Indeed, when sensitization also concerns pollens, the involvement of a profilin can be suspected with cross-reactions to other fruits of the rosaceae group (peach, apple, cherry) and often less severe reactions.
For fruit, skin tests with commercial solutions are disappointing and show a sensitivity of less than 40%. The sensitivity of the serological tests to the search for specific IgE is just as unconvincing with sensitivity prick skin tests with fresh foods show a concordance with the diagnosis of 90% for banana, avocado and chestnut; because of false positives, it is around 60% for kiwi and papaya. However to avoid all the bad circumstances you should know what products contain latex.
No allergy has increased as much as latex allergy in the last twenty years, while rubber has been used for millennia. The identification of the responsible proteins and the identification of groups at risk of allergy have made it possible to implement measures to reduce the allergen load during manufacture and to better control the exposure. A brake could therefore be put on this “epidemic”. A better knowledge of the allergens involved in cross allergies between latex and fruit should make it possible to better assess the risks and to propose more targeted care.