Press Release

Pollen Flight May Facilitate Respiratory Viral Infects – Even in Non-Allergics

Environmental Medicine Publishes Study with Considerable Scientific Relevance

The image depicts the immune defense against viruses in the epithelium after gene expression and production of interferones. (Copyright: C. Traidl-Hoffmann)

An international research collaboration, under the direction of Institute of Environmental Medicine, observed a correlation between pollen exposition and the downregulation of antiviral immune response in respiratory mucosa – and this first-ever even in healthy study participants. The central study results are:

  • If plant pollen reach the respiratory mucosa, the innate immune response is downregulated there.
  • This effect of pollen is independent of the allergy status. Even non-allergics could be more susceptible for viral infects of the respiratory tract.


The study summarizes findings from human cohorts (healthy non-allergics and patients with viral effects of the respiratory tract), an experimental allergy model, and human cell cultures. The results were published as “Pollen exposure weakens innate defense against respiratory viruses” by the journal Allergy in September 2019. The publication abstract can be read here. For PD Dr. Stefanie Gilles, head of the resarch field Environmental Immunology at UNIKA-T and first author of the paper, the study forms the basis for follow-up studies on pollen and viruses that are of considerable relevance to a number of scientific-medical topics. Principal investigator of the study, Professor Claudia Traidl-Hoffmann, gives an explanation on the matter: “ By the observed mechanism of pollen exposition downregulating the immune response to viruses in the nasal mucosa even in non-allergics, Environmental Medicine emphasizes the significance of research on allergies to interdisciplinary and related research fields.” 

Cutting-Edge Laboratory Research – From Nasal Mucosa to the Genetic Level

Mehmet Gökkaya, co-author of the study and PhD student at IEM, elaborates on the lab methods that have brought about the study results. RNA was isolated out of swabs from nasal mucosa and thus from the outmost barrier layer. By a real time analysis of the RNA, the gene expression of cells could be determined. In case viruses landed on the epithelium (the outmost cell layers of mucosa and skin), Gökkaya further explains, certain genes became activated and the infected cells produced so-called interferones. Interferones were transmitters on a molecular level that docked to receptors of immune cells and got them to either eliminate or disarm the cells infected by viruses. The study design involved the provocation of cells, adds the Biochemist. The study participants either applied a nasal spray with NaCl or with aqueous pollen extract (APE) on the nasal epithelium.By this, a key finding was revealed : The gene expression of interferones in epithelial cells, which are provocated by the pollen extract beforehand, is clearly downregulated and thus the viral defence becomes ineffective. 

Pollen Even Constrain the Antiviral Immune Response in Non-Allergics

Medical research has known for many years that viral infections of the respiratory tract are of special concern to allergics and asthmatics. A key finding of the study is, however, that pollen exposition weakens the antiviral response, even if no allergic sensitization to pollen can be diagnosed. The pollen substances that cause this effect could not have been identified yet, but the initiated change in immune response could. This especially implies the downregulation of interferone genes that are responsible for a quick defence to viruses. 

Climate Change Is the Cause of an Increase in Viral Effects of the Respiratory System

The fact that the flowering phase of many allergenic and air-pollinated plants in mid-Europe shifts towards the beginning of the calendar year could mean that the risk of respiratory infections could increase particularly during spring. The early information on pollen flight is of significance for those in the population that are possibly at special risk, such as asthmatics and patients with a deficient immune or lung function. A pollen flight forecast for the region of Augsburg that receives current data every hour is available for free by the UNIKA-T. Click here for current information on pollen flight. Follow Environmental Medicine at IEM on Twitter:@UNIKAT_IEM@Traidl_Hoffmann@TDamialis