Prevalence of sensitization to Artemisia allergens Art v 1, Art v 3 and Art v 60 kDa. Cross-reactivity among Art v 3 and other relevant lipid-transfer protein allergens M. Lombardero*, F. J. Garcı´a-Selle´sw, F. Polo*, L. Jimeno*, M. J. Chamorro*, G. Garcı´a-Casadoz, R. Sa´nchez-Mongez, A. Dı´az-Peralesz, G. Salcedoz and D. Barber* *Dept. I1D, ALK-Abello ´ SA, Madrid, Spain, wHospital Virgen de la Arrixaca, Murcia, Spain and zDept. Biotecnologı´a, ETS de Ingenieros Agro ´nomos, Madrid, Spain Summary Background Artemisia vulgaris is a widespread weed in the Mediterranean area and several allergens have been detected in its pollen. One of them, Art v 3, belongs to the lipid-transfer protein (LTP) family and its prevalence in Artemisia-sensitized patients or its relationship with other LTP allergens is not clear. Objective To assess the pattern of sensitization to an array of mugwort allergens in a Mediterranean population, and to study the cross-reactivity of Art v 3 with Pru p 3 and Par j 1, relevant LTP allergens in the area. Methods Skin prick test was performed with whole extracts (A. vulgaris, Parietaria judaica and peach) and pure natural allergens Art v 1, Art v 3, Art v 60kDa and Par j 1 in 24 mugwort-allergic patients from a Mediterranean area. In vitro assays included measurement of specific IgE and ELISA inhibition among LTP allergens. Results The three Artemisia allergens elicited a positive skin response in 70–80% of the patients. Seven patients were clearly sensitized to Par j 1 and 11 to Pru p 3. There was no correlation between Par j 1 and Pru p 3 sensitization, but a highly significant correlation was found between peach extract and Art v 3 as regards the skin response. No IgE cross-reactivity was observed between Art v 3/Par j 1 or Pru p 3/Par j 1. In contrast, Art v 3 significantly inhibited the binding to Pru p 3 of IgE from three patients’ sera out of six studied, but Pru p 3 was not able to inhibit the IgE binding to Art v 3. Conclusion Art v 3 is a major mugwort allergen and in some patients with IgE to both Art v 3 and Pru p 3, Art v 3 behaves as the primary sensitizing agent. Keywords Artemisia pollen, cross-reactivity, lipid transfer protein, Parietaria pollen, skin prick test Submitted 25 March 2004; revised 14 May 2004; accepted 26 May 2004 Introduction Pollen grains of mugwort (Artemisia vulgaris) are an important cause of pollinosis during late summer and fall in the temperate and humid zones of the northern hemisphere and the Mediterranean basin [1]. IgE-immunoblotting experi- ments carried out with sera from mugwort-allergic patients reveal mainly four allergenic structures with apparent molecular weights of about 60, 25–30, 15 and 13kDa [2]. The 60kDa allergen was first described by de la Hoz et al. [3] as a monomeric acidic glycoprotein that is recognized by the IgE from 73% of mugwort-allergic patients. This allergen was originally named Art v I. However, no sequence data were provided and the systematic name was not kept. It will be called Art v 60kDa throughout this paper. The allergen currently named Art v 1 in the official allergen list of the IUIS allergen nomenclature subcommittee has recently been cloned and expressed as a recombinant protein in Escherichia coli [4]. It is a glycoprotein to which 90% of individuals allergic to mugwort have specific IgE. Sequence analysis showed that Art v 1 is a secreted allergen with an N- terminal defensin-like domain, and a C-terminal region rich in hydroxyproline residues, some of which are O-glycosy- lated. The carbohydrate moiety is highly heterogeneous and influences the electrophoretic mobility of the allergen (apparent molecular weight in SDS-PAGE 25–30kDa). Besides Art v 1 and Art v 60 kDa, other IgE-binding structures have been detected in Artemisia vulgaris pollen with described prevalence of sensitization ranging from 30 to 50%. Art v 2 [5] is a 35 kDa glycoprotein composed of two subunits linked together by a disulphide bridge(s). Art v 3 [6] belongs to the family of non-specific lipid transfer proteins (LTPs) and has an apparent molecular weight of 13 kDa in SDS-PAGE. Finally, Art v 4 corresponds to the mugwort Correspondence: Dr Manuel Lombardero, ALK-Abello´ SA, C/Miguel Fleta 19, E-28037 Madrid, Spain. E-mail: manuel.lombardero@es.alk-abello.com Clin Exp Allergy 2004; 34:1415–1421 doi:10.1111/j.1365-2222.2004.02053.x r 2004 Blackwell Publishing Ltd 1415