Molecular Cloning and Expression of a New Allergen of Acacia farnesiana (Aca f 2)

Inhalation of pollens from different species of Acacia is a common cause of respiratory allergy in tropical areas of the world. Acacia farnesiana is commonly used as street trees in towns and ornamental shade trees in parks and gardens throughout arid and semi-arid regions of Asia. This study aimed to produce and purify the A. farnesiana pollen profilin (Aca f 2) and evaluate its nucleotide sequence homology with profilins of common allergenic plants to predict allergenic cross-reactivity. Thirty-nine patients who were allergic to Acacia pollens were included in the study. Cloning of Acacia profilin-coding sequence was performed by polymerase chain reaction using primers from Acacia pollen RNA. The cDNA of Acacia pollen profilin was then expressed in Escherichia coli using pET-21b(+) vector and purified by metal affinity chromatography. Immunoreactivity of the recombinant Acacia profilin (rAca f 2) was evaluated by specific ELISA, immunoblotting, and inhibition assays. The coding sequence of the Acacia profilin cDNA was recognized as a 399-bp open reading frame encoding 133 amino acid residues. Eighteen patients (18/39, 46.15%) had significant specific IgE levels against Aca f 2. Immunodetection and inhibition assays indicated that purified Aca f 2 might be the same as that in the crude extract. Aca f2, the first allergen from A. farnesiana pollen, was identified as belonging to the family of profilins. The amino acid sequence homology analysis showed high cross-reactivity between Aca f 2 and other profilins from botanically unrelated common allergenic plants.

A study of pollen prevalence in relation to pollen allergy in Malaysian asthmatics

In this paper we report results of skin prick tests (SPT) using pollen extracts on 200 patients with clinical symptoms of asthma, and results of a parallel study in which pollen was collected and classified over a period of 18 months. The patients were outpatients from the University Hospital in Kuala Lumpur, Malaysia, while the pollen grains were collected with a spore trap placed in the campus of the University of Malaya, approximately one kilometer from the University Hospital. Pollen extracts of 3 grasses (Bahia, Bermuda, rough pigweed) and 2 flowering trees, Acacia and Melaleuca, were used in the SPT. Of the 29.5% asthmatics with positive SPT reactions, 21.5% were to one or more of the grass pollens, 21.5% to Acacia and 7.5% to Melaleuca pollen. Acacia and Bermuda grass extracts were the most allergenic, which agreed with results of the pollen collection which showed grass and Acacia pollen grains to be the two most commonly found pollens.

Cross-reactivity between Acacia (wattle) and rye grass pollen allergens. Detection of allergens in Acacia (wattle) pollen

Immunoglobulin E (IgE), directed against components of Acacia (wattle) pollen, has been detected by radioallergosorbent tests (RAST) in the sera of some children and adults who develop allergic symptoms in the presence of flowering Acacia trees in Australia. All these subjects also had high levels of IgE directed against Lolium perenne (rye grass) pollen. Inhibition by RAST showed that most of the IgE molecules which bound to Acacia pollen components also bound to L. perenne pollen extracts, and to Glycoprotein 1, the major allergen of L. perenne pollen. In these assays, the allergens have been immobilized on polyvinyl chloride microtitre trays: the sensitivity of this approach is compared to that of commercial RAST kits.