A new study has found that the innate immune system of humans is capable of killing a fungus linked to airway inflammation in asthmatic and chronic sinusitis patients.
The research team from Mayo Clinic and the Virginia Bioinformatics Institute (VBI) have revealed that eosinophils, a particular type of white blood cell, exert a strong immune response against the environmental fungus Alternaria alternata.
"Our results strongly demonstrate that eosinophils have the capacity to recognize and exert immunological responses to certain fungi such as Alternaria," said principal investigator Hirohito Kita, M.D., from Mayo Clinic.
"We have shown that CD11b receptors on the surface of eosinophils recognize and adhere to beta-glucan, a major cell wall component of the fungus. This in turn sets in motion the release of toxic granule proteins by the white blood cells, leading to extensive damage and ultimate destruction of the fungus.
"To the best of our knowledge, this is the first time that live eosinophils and not just the intracellular components have been shown to target and destroy a fungus," Kita added.
With the help of fluorescence microscopy, the researchers determined the outcome of the interaction between eosinophils and A. alternata.
They found that the contact of fungus with eosinophils resulted in bright red fluorescence due to the damaged fungal cell wall and subsequent death of Alternaria.
"We have taken an important step in showing that the innate immune system of eosinophils is capable of targeting an asthma-associated fungus for destruction," said Kita.
The findings are published recently in the Journal of Immunology.