Pollen grains of queen sago (Cycas circinalis L.), a source of aeroallergen from West Bengal, India: an immunochemical approach

Cycas circinalis L. or queen sago is a common ornamental gymnosperm in tropics and subtropics. The objectives of the study were (a) to observe the seasonal variation of queen sago pollen in the atmosphere of a rural and an industrial area of West Bengal, India, (b) to visualize its allergenic potential on local population, and (c) to identify and isolate the important IgE-binding protein component present in the pollen extract. A two-year aerobiological survey was performed with Burkard personal volumetric sampler, and Cycas pollen was found to be present in air during April-July. Among 172 respiratory allergic patients of study area, 25.58% showed skin reaction to Cycas pollen extract. The allergenicity of the pollen extract was confirmed by in vivo (skin reaction test) and in vitro (IgE-ELISA and dot blotting) analyses and immunoblotting. Two components of 39.6 and 20.7 kDa were found to be the important IgE-binding proteins in pollen extract. The 20.7 kDa component was purified by two-step gel electrophoresis and it was found to retain its IgE reactivity. This component can be used for further work in diagnostic and therapeutic purpose in susceptible individuals. The overall study demonstrated that the pollen grains of Cycas circinalis is one of the important aeroallergen source of West Bengal, India,.