IGHE and asthma: Although the reason for boys being more susceptible to asthma and allergies than girls is not well established, a comprehensive review [16] conducted towards this end suggested the following possible reasons among others: (1) boys have narrower airways than girls (2) boys’ peripheral blood mononuclear cells (PBMCs) generated more IFN- in response to phytohaemagglutin stimulation than girls’ PMBCs, and (3) boy could be higher genetic predisposition to develop allergic disease than girls as evidenced by specific IgE and skin prick testing to common allergens.