ORIGINAL ARTICLES AAEM Ann Agric Environ Med 1999, 6, 53–56 Received: 23 March 1999 Accepted: 20 April 1999 ANTIGENIC RELATIONSHIP BETWEEN FOUR AIRBORNE PALM POLLEN GRAINS FROM CALCUTTA, INDIA Indrani Chowdhury, Pampa Chakraborty, Swati Gupta-Bhattacharya, Sunirmal Chanda Division of Palynology and Environmental Biology, Department of Botany, Bose Institute, Calcutta, India Chowdhury I, Chakraborty P, Gupta-Bhattacharya S, Chanda S: Antigenic relationship between four airborne palm pollen grains from Calcutta, India. Ann Agric Environ Med 1999, 6, 53–56. Abstract: The pollen grains of Areca catechu, Borassus flabellifer, Cocos nucifera and Phoenix sylvestris, all belonging to the family Aracaceae (Palmae), are airborne and found to be potent in causing human respiratory allergy. The present study was undertaken to discover the antigenic relationship, if any, in the four relevant palm pollen grains. The study was conducted by using Borassus and Phoenix antisera raised in rabbit. These antisera were used in rabbit IgG specific ELISA-inhibition and rocket immunoelectro-phoresis (RIE) assays for all four palm pollen extracts. In ELISA- inhibition, a distinct inhibition was obtained with comparable amount of soluble pollen protein. The RIE precipitin bands also revealed the presence of common antigenic components in the palm pollen. After isolation and purification, such common antigens may be useful in allergen immunotherapy in asthmatics. Address for correspondence: Professor Dr Sunirmal Chanda, Division of Palynology and Environmental Biology, Department of Botany, Bose Institute, 93/1 Acharya P.C. Road, Calcutta - 700 009, India. E-mail: swati@boseinst.ernet.in Key words: Cross reactivity, palm pollen, antigenicity. INTRODUCTION Pollen grains have been found to be very important in causing human respiratory allergic disorders. Although the primary treatment for asthma and allergic rhinitis is essentially pharmacological [14], allergen avoidance should be attempted and desensitization with appropriate allergen should always be considered in chronic and severe cases. This measure, of course, requires knowledge about the sensitizing agents and pollen types. While antigenic and allergenic cross-reaction is a well-established fact [8, 5], skin and serum tests reveal that pollen allergic subjects are rarely sensitive to a single species; rather they are sensitive to a number of different pollen types at a time [10]. Since it has important implications for allergen avoidance and desensitization of pollen allergen, the present study was undertaken to establish the antigenic relation of those taxonomically related pollen types. The observation was based on cross-reaction as an aid to clinical management of the subjects, on the basis of IgG- ELISA and rocket immunoelectrophoresis using rabbit antisera. Four major palm pollen types have been recorded from the air of Calcutta and suburbs, often in significant quantity and potent allergenicity [1, 2]. These are Areca catechu (areca palm), Borassus flabellifer (palmyra palm), Cocos nucifera (coconut palm) and Phoenix sylvestris (date sugar palm). The relevant palm trees are economically important in terms of yielding fruit, oil, sugar, liquors, etc., which grow naturally or are cultivated. MATERIALS AND METHODS Preparation of pollen extract. Fresh pollen samples were collected from the mature buds of the relevant plants. The pollen samples containing >90% pure pollen were defatted with diethyl ether and the extracts were prepared in phosphate buffered saline (PBS, 0.1 M Na- phosphate containing 0.15 M NaCl, pH 7.2) by stirring at 4°C for 24 h. The extracts were centrifuged at 12,500 × g