Airborne palynomorphs are regarded as important organic granules causing human allergic reactions such as pollinosis and asthma. There is need to understand the mechanism of pollen allergenicity, to ensure early prophylaxis by pollen-immunocompromised individuals. In the present study, monthly depositional amount of airborne pollen and fern spores, impact of the surrounding plants on pollen distribution and allergenicity of common airborne pollen types, were investigated at selected monitoring stations in Ebonyi and Anambra States, Southeastern Nigeria. Bioaerosols were collected with modified Tauber pollen samplers and subjected to conventional palynological treatment processes, microscopy and photomicrography. Enumeration of plants within the immediate vegetation showed that local plants produced some atmospheric pollen types at the study locations. Among other meteorological parameters, only relative humidity was found to yield statistically significant and positive correlation with monthly total airborne pollen concentrations in Anambra State. A positive but not significant correlation was also found between total airborne pollen counts and relative humidity in Ebonyi State. Nephrolepis sp., Pteris sp. and a trilete fern produced spores, while diatoms were also recovered. Some common pollen types including those of Syzygium guineense (Willd.) DC. and Senna siamea (Lam.) Irwin et Barneby in Ebonyi State; Mariscus alternifolius Vahl. and Zea mays L. in Anambra State, were collected in order to quantify and extract their crude protein contents for Mus musculus sensitization to achieve serology (ELISA) and haematology (differential and total white blood cell counts). Statistical significance was tested and observed in the correlation between amounts of haematological and serological parameters yielded by each test group; variations between amounts of these parameters yielded by each test group and those of the control, as well as at differing periods of sensitization. In the Senna siamea test group of Mus musculus, histopathological morbid characteristics were observed, including areas of necrosis (presence of dead cells) in the bronchi of a mortality; areas of necrosis and congestion in the bronchi and lungs of another mortality, respectively, after second sensitization. The study confirmed all the selected pollen types as potential sources of allergy at the study areas and revealed a multiplex of interplay among triggers of pollen allergy at different intervals of administration in mice, establishing a model of immunological reactions to varied pollen antigens in humans.