Aerofloral investigation and allergenic potentials of two dominant airborne pollen types at selected sites in South-western Nigeria

Abstract

Airborne pollen triggers immune cells to release inflammatory chemical mediators, inducing respiratory conditions among susceptible individuals. This present study aimed at investigating the monthly depositional rate of pollen and fern spores with the aid of a modified Tauber pollen sampler, for a period of 1 year, examining airborne pollen–vegetation relationships and allergenic potentials of dominant airborne pollen types at selected study sites in Osun and Ogun states, South-western Nigeria. This involved collection, acetolysis and microscopy of residual solutions. Plants within the immediate vegetation of these sites were enumerated. Crude protein contents were extracted from pollen of Tridax procumbens L. (dominant in Osun state) and Alchornea cordifolia (Schum. & Thonn.) Mull. Arg. (dominant in Osun and Ogun states), used in Mus musculus sensitization. Blood samples were obtained from the pre-orbital vein of M. musculus L., processed for haematological (differential and total white blood cell counts) and serological studies. ELISA was employed in measuring the levels of serological parameters: IgE and cytokines (TNF-α, IL-5 and IL-13). Statistical significance (P < .05) was tested in the correlation between the levels of haematological and serological parameters elicited by each test group, differences between the levels of haematological and serological parameters elicited by each test group and those of the control, as well as at varied sensitization periods. In the results obtained, airborne pollen types of A. cordifolia, T. procumbens, Elaeis guineensis Jacq. and Poaceae were dominant in Osun state; A. cordifolia, Senna sp. and Poaceae were dominant in Ogun state. Spores of Nephrolepis biserrata (Sw.) Schott, Pteris sp. and a trilete fern were also recovered. Some pollen types were produced by local plants at the study sites. Neutrophils, lymphocytes, monocytes and eosinophils were the identified differential white blood cells. Statistical significance was observed in the correlation between the levels of certain haematological and serological parameters elicited by the test groups, differences between the levels of certain haematological and serological parameters elicited by each test group and those of the control, as well as at some sensitization periods. Hair loss (alopecia) was observed on the skin of a M. musculus in the A. cordifolia test group. This study has identified potential pollen allergens at the study sites; hence, their allergenicity should be further conducted on humans.