Rm229 rAlt a 1

Allergens within Molds and other Microorganisms

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  • Latin name: Alternaria alternata/Alternaria tenuis
  • Common names: Alt-1
  • Source material: An E. coli strain, which carries a cloned cDNA encoding Alternaria alternata allergen Alt a 1.
Recombinant allergen
rAlt a 1 from Alternaria alternata (1-3)
 
Biological function
Unknown.
 
Mw
29.2 – 31 kDa.
 
Allergen description
More than 9 allergens have been described in A. alternata extracts, although only 2 of them are major allergens. Alt a 1 is a dimer of 29 kDa that dissociates into 14.5 and 16 kDa subunits under reducing conditions (3). Studies indicate that this allergen may have several conformational or structural isoforms, which may be responsible for the allergen appearing to have a number of different molecular sizes (4-5).
 
Alt a 1 is recognised by approximately 80% to 100% of all Alternaria-allergic patients (3, 6). rAlt a 1 has been shown to be similar to natural Alt a 1. In a study of A. alternata-sensitised individuals, 85.7% to >90% were shown to be sensitised to to rAlt a 1 (1, 3). Similarly, in a study of patients with A. alternata allergy, sensitisation could be detected by means of skin-specific IgE. No false-positive results were obtained with control patients, even at the highest concentration (2). Evaluation of recombinant Alt a 1 using skin-specific IgE determination was positive in 6 of 7 individuals allergic to Alternaria. In contrast, in a study using commercially available A. alternata extracts, researchers failed to correctly diagnose Alternaria-allergic patients in 2/10 cases (1).
 
In a study of 42 patients allergic to A. alternata, 10 atopic patients were found to have no skin-specific IgE for the A. alternata extract; commercial extracts were used for testing. However, all patients were shown to have skin-specific IgE to A. alternata when purified allergens were used for testing. No false-positive reactions were detected. Analysis showed no IgE-binding differences between nAlt a 1 and rAlt a 1. Specific IgE levels to nAlt a 1 or rAlt a 1 showed significant correlation and similar sensitivity and specificity (2).

Compiled by Dr Harris Steinman, harris@zingsolutions.com.

References:

    1. Unger A, Stoger P, Simon-Nobbe B, Susani M, Crameri R, Ebner C, Hintner H, Breitenbach M. Clinical testing of recombinant allergens of the mold Alternaria alternata. Int Arch Allergy Immunol 1999;118(2-4):220-1
    2. Asturias JA, Ibarrola I, Ferrer A, Andreu C, Lopez-Pascual E, Quiralte J, Florido F, Martinez A. Diagnosis of Alternaria alternata sensitization with natural and recombinant Alt a 1 allergens. J Allergy Clin Immunol 2005;115(6):1210-7.
    3. De Vouge MW, Thaker AJ, Curran IH, Zhang L, Muradia G, Rode H, Vijay HM. Isolation and expression of a cDNA clone encoding an Alternaria alternata Alt a 1 subunit. Int Arch Allergy Immunol 1996;111(4):385-95
    4. Curran IH, Young NM, Burton M, Vijay HM. Purification and characterization of Alt a-29 from Alternaria alternata. Int Arch Allergy Immunol 1993;102(3):267-75
    5. Aden E, Weber B, Bossert J, Teppke M, Frank E, Wahl R, Fiebig H, Cromwell O. Standardization of Alternaria alternata: extraction and quantification of alt a 1 by using an mAb-based 2-site binding assay. J Allergy Clin Immunol 1999;104(1):128-35
    6. Yunginger  JW, Jones RT, Nesheim ME, Geller M. Studies on Alternaria allergens. III. Isolation of a major allergenic traction (ALT-1). J Allergy Clin Immunol 1980;66:138-147

2006



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