Amaranthus Pollen Allergens: Protein Diversity and Impact on Allergy Diagnosis

Allergenic weeds dominate the pollen air flora (> 80%) of Saudi Arabian environment. Two species viz Amaranthus viridis (Av) (Slender or Green Amaranth) and A. lividus (Al) are the most prevalent components of this flora. Although all Amaranthus species appear to be allergenic and a potential cause of respiratory allergy, neither a diagnostic extract nor raw pollen grains for Av is available commercially for comparative study on patients. Thus, in order to determine IgE mediated sensitization of Av and to observe cross-reactivity patterns with other species, an allergological study was conducted using seven Amaranthus species. Row pollen of 5 Amaranthus species were acquired from two commercial sources (Greer USA, Allergon Europe) while Av & Al pollen was collected indigenously. Allergenic extracts were prepared using pollen grains from both sources in buffered saline. Skin Prick Test (SPT) was conducted on 132 allergic patients using all seven extracts. Protein separation of all seven Amaranthus species was conducted by SDSPAGE. The results indicate that the species of Amaranthus vary in their protein profiles with a pattern of cross SPT reactivity between the species. However, as the exposure takes place with prevalent pollen form Av and Al, the commercial extracts using species not present in the region may not be fully relevant to the patients for diagnosis and immunotherapy