Route Of Exposure

Allergen Exposure

Chick pea is a leguminous plant which produces hazel nut-shaped, nut-flavoured seeds. Chick pea is an important source of proteins, carbohydrates, B-group vitamins and certain minerals, particularly to the populations of developing nations. India contributes over 75% of the Chick pea production in the world. In India itself, this legume is consumed mostly as dhal, whole seeds, and several types of traditional, fermented, deep fried, sweetened, and puffed products. Chick peas are a staple food in the Middle East. Chick peas are also used extensively in the Mediterranean, especially in Spain. The use of Chick peas has spread along with ethnic cuisines.

The Chick pea is unknown in the wild, though there are some related wild species. Chick peas are available canned, dried and sometimes fresh. Chick pea seeds are eaten fresh as green vegetables; parched, fried, roasted, and boiled; and as a snack food, sweet and condiment. Hummus is an especially popular Chick pea recipe. Seeds are roasted and ground and the flour can be used in soup, as dhal (which has a number of uses as an ingredient), and to make bread. Sprouted seeds are eaten as a vegetable or added to salads. Young shoots and green pods are eaten like spinach (but may be toxic: see under Other reactions). A small proportion of Chick pea is used to produce fermented food. The roasted seed or root can be used as a coffee substitute. Acid exudate from the seedpod can be eaten as a type of vinegar.

The acid exudate is astringent. It has been used in the treatment of a number of ailments, including diarrhea.

Unexpected exposure

Parts of the plant can serve as animal feed, and can be made into adhesive, dye, and starch.

Clinical Relevance

Allergen Description

Immunoblot analysis has demonstrated that 70, 64, 35, and 26 kDa proteins are major allergens. Other studies have detected multiple allergens in both raw and boiled Chick pea extracts in the molecular weight range of 10-106 kDa, of which the majority were heat-stable. The following allergens have been characterised:

The presence of an allergen belonging to the profilin family has been suggested by a study examining the possible association of oral allergy syndrome with Plane tree pollen (Platanus acerifolia). This has been questioned by another study. A beta-1,3-glucanase and two chitinases have been isolated from Chick pea. One of the chitinases, a 32 kDa protein, was shown to be a class I chitinase, and the second, a 28 kDa protein, showed homology to class III chitinases. The allergenic significance of these proteins has not yet been determined. Infection of the Chick pea plant was shown to initiate the formation of a thaumatin-like protein in Chick pea leaves. Whether this protein occurs in the seed of the plant or whether it has allergenic potential has not been determined yet. Also, a trypsin and chymotrypsin inhibitor has been isolated in Chick pea. The clinical significance of this has not yet been determined.

Potential Cross Reactivity

An extensive cross-reactivity among the different individual species of the Fabaceae (legume family) could be expected but in fact does not occur frequently. In an early study, an in vitro study, the specific IgE binding by protein extracts of 11 food legumes was examined by IgE antibody determination and RAST inhibition. Cross-allergenicity was demonstrated to be most marked between the extracts of Peanut, Garden pea, Chick pea, and Soybean (13.) Legumes have a high degree of immunological cross-reactivity, at least in in vitro studies. The allergenicity of legumes is mainly is mainly related to allergens from the storage proteins of seeds. Vicilins from this group of proteins could be an important common allergen in clinical allergy to legumes. Other panallergens of increasing importance are lipid transfer proteins. However, some clinical studies have reported that there is little cross-reactivity between members of the legume family.

In fact, although the different legumes have structurally homologous proteins, they are not all equally allergenic, thus making it difficult to distinguish in vitro and in vivo cross-reactivity. Studies in Spanish patients, in whom a high prevalence of chick pea allergy occurs, have shown that most of the patients are sensitised to more than one species. A great degree of cross-reactivity was demonstrated among Lentil, Chick pea, Pea and Peanut by inhibition studies. The authors report that unlike the Anglo-Saxon population, this phenomenon implies clinical sensitisation for many Spanish children and that the majority of these patients have had symptoms with more than one legume (median 3 legumes). Of 39 patients challenged with two or more legumes, 32 (82 %) reacted to two or more legumes: 43,5 % to 3, 25,6 % to 2, 13 % to 4 legumes. Seventy three per cent of the patients challenged with Lentil and Pea had positive challenge to both, 69,4 % to Lentil and Chick pea, 60 % to Chickpea and 64,3 % to Lentil, Chick-Pea and Pea simultaneously. Peanut allergy was associated with to allergy to Lentil, Chick pea and Pea but less frequently, whereas White bean and Green bean and Soybean were well tolerated by children allergic to other legumes. The authors stressed that in spite of an evident clinical and immunological cross-reactivity, the diagnosis of legume allergy should not be based only on allergen-specific IgE tests.

Nevertheless, some reports of specific cross-reactivity between certain members of this family have been published. Lentils appear to be cross-reactive with Chick pea and beans, and cross-reactivity was shown between Pea, Soybean, White bean, Peanut, Lentil, Fennel, Guar gum, Carob bean, Tragacanth, Chick pea and Liquorice.

Of 720 patients evaluated for oral allergy syndrome (OAS), and sensitisation to Plane tree (P. acerifolia) pollen, 61 (8.48%) were sensitised to pollen from this tree, and food allergy was reported in 32 (52.45%) of these 61 patients. The food allergens most frequently implicated were Hazel nuts, Peach, Apple, Peanuts, Maize, Chick pea and Lettuce. The study concluded that cross-reactivity was observed between P. acerifolia pollen and plant-derived foods, and that OAS in these patients may have been caused by primary respiratory sensitisation to Plane tree pollen. The authors suggested that profilin may be the responsible allergen.

Cross-reactivity between allergens from Latex and Chick pea was recently described in a boy with spina bifida with allergy to Chick pea, which developed after the appearance of Latex allergy symptoms. IgE antibodies to Latex and Chick pea were demonstrated by SPT and serum IgE antibodies.

In a Spanish study, symptomatic hypersensitivity to Chick peas was frequently associated with Lentil allergy. In another Spanish study, aimed at determining the prevalence of Lupin sensitisation in 1,160 subjects consulting allergologists, a 4,1 % sensitisation rate (28 patients) was found, with 75% co-sensitisation between Lupin and legumes. Of 28 patients, 13 were shown to have skin reactivity to Chick pea, 8 to Pea, 12 to Peanut, 13 to Bean, and 7 to Lentil (but 18 were not tested for Lentil).

Clinical Experience

IgE-mediated reactions

Chick pea may commonly induce symptoms of food allergy in sensitised individuals, in particular in communities where this legume forms part of the staple diet such as India, in the Mediterranean area and Middle East. The clinical manifestations of the allergy to Chick pea are similar to that for all legumes ranging from oral allergy syndrome, urticaria, angioedema, rhinitis, asthma, to anaphylaxis and death.

Legumes are an important ingredient in the Mediterranean diet. In the Mediterranean area and Middle East, the most commonly consumed legumes are Lentils and Chickpea. (In the United States, United Kingdom and south-east Asia, the major legumes involved in food allergy are considered to be Peanut and Soy bean). Among Spanish children, sensitivity to legumes is the fifth most prevalent food allergy. Lentil and Chick pea are the most frequent cause of allergic reactions to legumes in Spanish children but this may vary from one geographical area to another: in a study of food allergy in 674 patients referred to an Allergy Unit in Spain, the prevalence of food legume allergy was 9.1%. Two patients were challenge-positive to Chick pea.

Chick pea has been reported to be an important allergen in India. Of 1,400 patients screened for Chick pea allergy, 142 were food allergy-positive on history, of which 59 implicated Chick peas. Subsequent challenges demonstrated that 31 were DBPCFC-positive for Chick pea. Further reports from India indicate that Chick pea is an important source of allergens that can cause IgE-mediated hypersensitivity reactions ranging from rhinitis to anaphylaxis. The ELISA results did not correlate well with the DBPCFC results; however, the skin test results correlated with DBPCFC in 75% of patients.

Other symptoms reported from Chick pea allergy include urticaria, angioedema, abdominal symptoms, rhinoconjunctivitis and/or asthma, which may follow ingestion or inhalation of vapours from cooked Chick pea and other cooked legumes (Lentil, bean). Lentil was found to induce the most severe reactions. Other studies have also implicated Chick pea in the genesis of allergic symptoms following inhalation. Twelve children with an IgE-mediated food allergy who developed asthma on inhalational exposure to food were identified in one study. The implicated foods were Fish, Chick pea, Milk, Egg and Buckwheat. Nine out of the 12 children consented to undergo a bronchial food challenge, of which 5 challenges were positive, with objective clinical features of asthma. Additionally, two children developed late-phase symptoms, with a decrease in lung function. Positive reactions were seen with Fish, Chick pea and Buckwheat. Allergic reactions to legumes through inhalation have also been described in adults, notably a 20-year-old man who experienced asthmatic attacks when exposed to the steam from cooking either Chick pea or Lentil. Type I hypersensitivity to the antigens in these legumes was demonstrated by means of immediate skin reactivity, histamine release tests, IgE antibody determinations and RAST inhibition. Specific bronchial challenges with the heated (75 °C for 30 min) extracts of Chick pea and Lentil elicited isolated immediate responses. A 20% reduction in lung function after inhalation of aerosolised Fish, Buckwheat and Chick pea has been reported. Importantly, Chick pea allergens appear to be heat-stable. Sera of 29 children with a history of allergic reactions after ingestion of Chick pea, and positive skin tests to this legume, were used to study the allergenic composition of raw and boiled Chick pea extracts. There were no significant differences between IgE antibody levels to the raw and boiled extracts. Patients with a current clinical allergy to Chick pea were shown to have statistically higher IgE antibody levels than tolerant patients and controls.

Reactions to Chick pea may be severe. An 8-year-old girl suffered with contact urticaria from raw Chick peas and an anaphylactic reaction after ingestion of cooked Chick peas. Anaphylactic reactions have been described by other authors. Features of anaphylaxis including severe wheezing and urticaria occurring 1 hour after the ingestion of Chick pea were reported in an 8 year old Indian girl. She had a previous history of wheezing following inhalation of chick pea flour or its vapours emitted while being cooked. External application of chickpea paste had resulted in urticaria. Specific IgE to Chick pea was detected both in serum and in skin.

Occupational exposure may result in allergic reactions. Asthma has been reported in individuals exposed to vapours from cooking of some kinds of legumes (Peas, Chick peas, beans, Lentils). Also reported was the case of a 20-year-old man who experienced asthmatic attacks when exposed to the steam from cooking either Chick pea or Lentil. Type I hypersensitivity to the antigens in these legumes was demonstrated by means of immediate skin reactivity, histamine release tests, IgE antibody determinations and RAST inhibition

Other reactions

The foliage and seedpods contain oxalic acid and can irritate the skin. Oxalic acid can lock up certain nutrients in the diet, especially calcium, and therefore heavy use of foods that contain this substance can lead to nutritional deficiencies. Cooking will greatly reduce the oxalic acid content. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet, since the oxalic acid can aggravate their condition.