The study, published in Food Chemistry, found that the newly identified allergen, known as ARP60S, is related with allergic sensitisation and shows Immunoglobulin E (IgE) binding capacity – IgE is the predominant antibody associated with an allergic response.
“The capacity to bind IgE has been suggested in different tomato proteins but new allergens, related probably with different populations, are now under study … We have identified a new tomato allergen with high homology with previous known and described allergens from moulds and almond,” said the researchers, led by Maria Angeles Lopez-Matas, from Laboratorios LETI, Spain.
The discovery of the new allergen adds to the current knowledge of food allergens for which food manufacturers need to be aware; due to the challenges posed by ingredients with allergic potential being used in foods where their presence may not be immediately apparent.
Food allergies are caused by an adverse immune response, usually to a food protein, when the immune system identifies a protein as harmful. Estimates of incidence vary, but in recent years the sector of the food industry catering to allergy-sufferers – the ‘free-from’ market – has developed rapidly.
The authors said that although the prevalence of tomato allergy remains relatively unknown, the incidence of sensitisation can be considered important in areas where the fruit is frequently consumed.
Previous research (Woods et al, European Journal of Clinical Nutrition, Vol. 55, Pages 298-304) estimated that the prevalence of tomato sensitisation among subjects attending Allergy Clinics in the Mediterranean Coast of Spain, was approximately 6.5 per cent, however worldwide the self-reported estimation of allergy to tomato is about 0.3 per cent, noted the authors.
They explained that until now three tomato allergens have been characterised: Lyc e 1 (profilin), Lyc e 2 (beta-fructofuranosidase), and Lyc e 3 (lipid transfer protein – LTP).
“However, previous studies have suggested and demonstrated the existence of other proteins involved in tomato sensitisation … The objective of this study was to identify new tomato allergens by molecular biology techniques,” said Lopez-Matas and her colleagues.
Tomato peel DNA from a stock library was screened using a pool of serum from tomato sensitised individuals.
From the data, the researchers were able to identify sequences of allergens that caused sensitisation reactions.
Lopez-Matas and her co-workers identified the new allergen identified, containing 34 amino acids on the C-terminal region of the acidic ribosomal protein 60S.
They reported that the protein showed more than 85 per cent of homology (similarity) with fungal allergens and 93.8 per cent homology with the almond allergen Pru du 5.
The authors reported that an immunoblot test showed that a recombinant version of the ARP60S allergen protein is recognised by IgE. They concluded that because the allergen has not been identified or purified under native conditions, the relevance and clinical importance of the allergen “should be studied further.”
Source: Food Chemistry
Volume 127, Issue 2, Pages 638-640, doi: 10.1016/j.foodchem.2010.12.145
“Acidic ribosomal protein 60S: A new tomato allergen”
Authors: M.A. López-Matas, A. Ferrer, C.H. Larramendi, A.J. Huertas, J.A. Pagán, et al