rAra h 9 LTP, Peanut

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Code: f427
Latin name: Arachis hypogaea
Source material: rAra h 9 is a CCD-free recombinant protein
Common names: Non-specific lipid transfer protein (ns-LTP), member of the pathogenesis-related 14 (PR-14) protein family.

Clinical Utility

Recombinant Ara h 9 is a marker of sensitization to peanut lipid transfer protein (LTP). LTPs are often associated with systemic and severe reactions in addition to oral allergy syndrome (OAS). However, severe reactions to peanut due to LTP have so far not been well documented. Since LTPs are generally stable to heat and resistant digestion, there is a risk for allergic reactions also to cooked and processed food.

Allergen Description

In contrast to tree nuts, peanuts are the seeds of an annual legume that grows close to the ground and produces its fruits below the soil surface. Peanut is a member of the Fabaceae family and contains at least 32 different proteins of which about 18 have been identified as capable of binding specific IgE (1). Ara h 9 is a lipid transfer protein (2-5). Lipid transfer proteins (LTPs) are small molecules of approximately 9 kDa - 10 kDa and are highly resistant to digestion and heat denaturation (3, 6-10). LTPs are highly conserved and widely distributed throughout the plant kingdom. Their biological function is to facilitate the transport of lipids, phospholipids and galactolipids across cellular membranes. They are also believed to have a role in defence against pathogens and are therefore classified as belonging to a family of pathogenesis-related (PR) proteins, PR-14. Several LTPs have been identified as relevant allergens in plant foods and pollens.


LTPs are panallergens and strong cross-reactivity can be displayed among various plant food LTPs (11). Significant cross-reactivity between Ara h 9 and other LTPs in foods should be considered and is expected to be particularly relevant in southern Europe, where LTPs play an important role in food allergy (13). Other fruits and vegetables containing lipid transfer proteins that may result in cross-reactivity include sweet chestnut, cabbage, walnut, lettuce, pomegranate and hazelnut (5, 14-18). Ara h 9 shares 60-70% amino sequence identity with LTPs from a number of commonly consumed foods, including peach, apple, pear, plum, cherry, hazelnut, lentils, sunflower, beans, chestnut and strawberry.

Clinical Experience

In southern Europe food-allergic individuals sensitized to LTPs frequently experience both OAS and systemic symptoms after eating an offending food (12). Even if LTPs are believed to induce sensitization mainly by the oral route, as association to certain LTP-containing pollens, such as plane tree, mugwort and Parietaria pollen, cannot be excluded. Due to its stability to food processing and resistance to proteolytic digestion, it has been proposed that LTP may reach the intestinal tract in an almost unmodified form (12, 19).


  1. Dean TP.Immunological responses in peanut allergy. [Editorial] Clin Exp Allergy 1998;28:7-9.
  2. International Union of Immunological Societies Allergen Nomenclature: IUIS official list http://www.allergen.org/List.htm 2008.
  3. Asero R, Mistrello G, Roncarolo D, Amato S, Caldironi G, Barocci F, Van Ree R. Immunological cross-reactivity between lipid transfer proteins from botanically unrelated plant-derived foods: a clinical study. Allergy 2002;57(10):900-6.
  4. Asero R, Mistrello G, Roncarolo D, de Vries SC, Gautier MF, Ciurana CL, Verbeek E, Mohammadi T, Knul-Brettlova V, Akkerdaas JH, Bulder I, Aalberse RC , van Ree R. Lipid transfer protein: a pan-allergen in plant-derived foods that is highly resistant to pepsin digestion. Int Arch Allergy Immunol 2000;122(1):20-32.
  5. Enrique E, Utz M, de Mateo JA, Castello JV, Malek T, Pineda F. Allergy to lipid transfer proteins: cross-reactivity among pomegranate, hazelnut, and peanut. Ann Allergy Asthma Immunol 2006;96(1):122-3.
  6. Asero R, Mistrello G, Roncarolo D, Amato S. Relationship between peach lipid transfer protein specific IgE levels and hypersensitivity to non- Rosaceae vegetable foods in patients allergic to lipid transfer protein. Ann Allergy Asthma Immunol 2004;92(2):268-72.
  7. Asero R, Mistrello G, Roncarolo D, Amato S, Falagiani P. Analysis of the heat stability of lipid transfer protein from apple. [Letter] J Allergy Clin Immunol 2003;112(5):1009-11.
  8. Pastorello EA, Pompei C, Pravettoni V, Farioli L, Calamari AM, Scibilia J, Robino AM, Conti A, Iametti S, Fortunato D, Bonomi S, Ortolani C. Lipid-transfer protein is the major maize allergen maintaining IgE-binding activity after cooking at 100 degrees C, as demonstrated in anaphylactic patients and patients with positive double-blind, placebocontrolled food challenge results. J Allergy Clin Immunol 2003;112(4):775-83.
  9. Asero R, Amato S, Alfieri B, Folloni S, Mistrello G. Rice: Another potential cause of food allergy in patients sensitized to lipid transfer protein. Int Arch Allergy Immunol 2007;143(1):69-74.
  10. Scheurer S, Lauer I, Foetisch K, Moncin MS, Retzek M, Hartz C, Enrique E, Lidholm J, Cistero-Bahima A, Vieths S. Strong allergenicity of Pru av 3, the lipid transfer protein from cherry, is related to high stability against thermal processing and digestion. J Allergy Clin Immunol 2004;114(4):900-7.
  11. Richard C, Leduc V, Battais F. Plant lipid transfer proteins (LTPS): biochemical aspect in panallergen--structural and functional features, and allergenicity. Allerg Immunol (Paris) 2007;39(3):76-84. 12.
  12. Asero R. Detection and clinical characterization of patients with oral allergy syndrome caused by stable allergens in Rosaceae and nuts. Ann Allergy Asthma Immunol 1999;83(5):377-83
  13. Schocker F, Luttkopf D, Scheurer S, Petersen A, Cistero-Bahima A, Enrique E, San Miguel-Moncin M, Akkerdaas J, van Ree R, Vieths S, Becker WM. Recombinant lipid transfer protein Cor a 8 from hazelnut: a new tool for in vitro diagnosis of potentially severe hazelnut allergy. J Allergy Clin Immunol 2004;113(1):141-7.
  14. Sanchez-Monge R, Blanco C, Lopez-Torrejon G, Cumplido J, Recas M, Figueroa J, Carrillo T, Salcedo G. Differential allergen sensitization patterns in chestnut allergy with or without associated latex-fruit syndrome. J Allergy Clin Immunol 2006;118(3):705-10.
  15. Palacin A, Cumplido J, Figueroa J, Ahrazem O, Sanchez-Monge R, Carrillo T, Salcedo G, Blanco C. Cabbage lipid transfer protein Bra o 3 is a major allergen responsible for cross-reactivity between plant foods and pollens. J Allergy Clin Immunol 2006;117(6):1423-9.
  16. Pastorello EA, Farioli L, Pravettoni V, Robino AM, Scibilia J, Fortunato D, Conti A, Borgonovo L, Bengtsson A, Ortolani C. Lipid transfer protein and vicilin are important walnut allergens in patients not allergic to pollen. J Allergy Clin Immunol 2004;114(4):908-14.
  17. San M iguel-Moncin M , K rail M , Scheurer S, E nrique E , A lonso R , Conti A, Cistero-Bahima A, Vieths S. Lettuce anaphylaxis: identification of a lipid transfer protein as the major allergen. Allergy 2003;58(6):511-7.
  18. Pastorello EA, Vieths S, Pravettoni V, Farioli L, Trambaioli C, Fortunato D, Lüttkopf D, Calamari M, Ansaloni R, Scibilia J, Ballmer-Weber BK, Poulsen LK, Wütrich B, Hansen KS, Robino AM, Ortolani C, Conti A. Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results. J Allergy Clin Immunol 2002;109(3):563-70.
  19. Salcedo G, Sánchez-Monge R, Barber D, Díaz-Perales A. Plant non-specific lipid transfer proteins: an interface between plant defence and human allergy. Biochim Biophys Acta 2007;1771(6):781-91.


As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.