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The role of air pollution has been suspected to be an important factor in the recent increase in the incidence of respiratory diseases. The ambient air, which is the carrier of pollen grains, also incorporates pollutants from the atmosphere, leading to alteration of the pollen proteins. Several studies have reported higher risk of development of pollinosis in the areas of dense vehicular traffic as compared to the less polluted areas. The objective of the present investigation was to study the effect of chemical air pollutants (SO2 and NO 2 ) on the soluble total protein content of the pollen of Ricinus communis taken as a model system. Pollen grains of R. communis were collected and exposed to different (100, 200, 300, 400 and 500 μg/m 3 ) concentrations of SO 2 and NO 2 individually, as well as together, for 8, 16, 32 and 48 hours. Proteins were extracted from exposed pollen and also unexposed pollen, which acted as control. The variation found in the protein content was analysed statistically. In the exposed pollen, total protein content showed a significant decrease (p<0.05) in the extracts from the unexposed pollen to SO 2 and NO 2 . It varied from 1.84 to 11.01 mg/ml for the extracts from pollen exposed to SO 2 only, whereas NO 2 exposure recorded values for total protein from 0.82 to 3.44 mg/ml only. There was a gradual decrease in the soluble protein content with increase in the concentration and duration of exposure in the pollen exposed to SO 2 and NO 2 together (p<0.05). [ABSTRACT FROM AUTHOR]

Allergic diseases such as bronchial asthma, allergic rhinitis and atopic dermatitis are dramatically increasing all over the world including developing countries like India. Today, more than 30 % of the population is known to suffer from one or other allergic ailment. Major causative agents implicated are pollen grains, fungal spores, dust mites, insect debris, animal epithelia, etc. Several aerobiological studies have been conducted in different parts of the country to ascertain aerial concentration and seasonality of pollen grains and fungi. Recently, an "All India Coordinated Project on Aeroallergens and Human Health" was undertaken to discover the quantitative and qualitative prevalence of aerosols at 18 different centres in the country. Predominant airborne pollen are Holoptelea, Poaceae, Asteraceae, Eucalyptus, Casuarina, Putanjiva, Cassia, Quercus, Cocos, Pinus, Cedrus, Ailanthus, Cheno/Amaranth, Cyperus, Argemone, Xanthium, Parthenium and others. Clinical and immunological evaluations have revealed allergenically important texa - some of them for the first time. Allergenically important pollen are Prosopis juliflora, Ricinus communis, Morus, Mallotus, Alnus, Querecus, Cedrus, Argemone, Amaranthus, Chenopodium, Holoptelea, Brassica, Cocos, Cannabis, Parthenium, Cassia and grasses. Further cross-reactivity of the IgE antibodies is a common phenomenon among various pollen allergens. Ricinus communis pollen from commonly growing weeds in India, cross-reacts with latex (Hevea brasiliensis), Mercurialis annua and also with seeds of Ricinus communis - all belonging to family Euphorbiaceae. Areca catechu cross-reacts with other members of Arecaceae such as Phoenix sylvestris, Cocos nucifera and Borassus flabelifer. Several reports on pollen and fruit syndrome have been analyzed. Experiments conducted by us revealed that pollutants (NO(2) and SO(2)) not only affect pollen morphology but also changes their allergenic potency. Immunotherapy with recombinant proteins having similar epitopes from different allergens have been advocated, besides allergen avoidance.

Allergen cross-reactions among three strongly sensitizing Euphorbiaceae species, i.e., the rubber tree (Hevea brasiliensis), castor bean (Ricinus communis), and the Mediterranean weed Mercurialis annua were studied in Finnish patients (n = 25) allergic to natural rubber latex (NRL), but with no known exposure to castor bean or M. annua, and French patients allergic to castor bean (n = 26) or to M. annua (n = 9), but not to NRL. In immunoglobulin E (IgE)-immunoblotting, 28% of NRL-allergic patient sera recognized castor bean seed and 48% reacted to castor bean pollen proteins. Likewise, 35% of the NRL-allergic patient sera bound to M. annua pollen allergens. Nineteen percent of castor bean-allergic patients showed IgE to NRL and 8% to M. annua proteins. Sera from patients allergic to M. annua reacted in 44% to NRL, in 56% to castor bean seed, and in 78% to castor bean pollen proteins. In immunoblotting, castor bean seed extract inhibited the binding of NRL-reactive IgE to 20 kDa, 30 kDa of NRL, and 55 kDa of proteins; NRL extract, in turn, inhibited the binding of castor bean-reactive IgE to 14, 21-22, 29, and 32-34 kDa of castor bean proteins. In ELISA inhibition, NRL extract inhibited 33% of the binding of M. annua--reactive IgE of pooled sera to M. annua pollen. In conclusion, allergen cross-reactivity in vitro was observed among three botanically related Euphorbiaceae members, H. brasiliensis, R. communis, and M. annua, but the molecular specificity of the observed cross-reactions as well as their clinical significance remains to be elucidated. Allergen cross-reactivity should be taken into account in diagnostic work.

Amaranthus spinosus (Fam. Amaranthaceae) is an important aeroallergen in India and grows commonly in different parts of the country. In spite of its clinical significance in Type I hypersensitivity disorders, the antigenic and the allergenic properties of the pollen have not been systematically resolved. We investigated antigenic and allergenic properties of 5 pollen samples of Amaranthus spinosus collected from the Delhi area at fortnightly intervals. The protein content did not exhibit statistically significant variability. However, samples collected during the peak flowering season showed higher protein content. Biochemical characterization of samples showed multiple protein fractions by IEF and SDS-PAGE analysis. Samples collected during peak season showed a slightly higher number of bands (22) in the mw range of 14-70 kD. Seven protein fractions of 70, 66, 60, 50, 40, 30 and 14 kD were observed to have IgE binding capabilities and 9 were treated as allergenic. The observations will be helpful in standardizing pollen antigens for diagnosis and immunotherapy in India.