Immune responses in the lung of the African Lungfish (Protopterus dolloi) Exposed to Airborne Allergens

Several studies indicate that Dipnoid fish are the ancestors of all tetrapods. Dipnoid fish (lungfishes) have dual breathing modes and represent the first vertebrates to primarily rely on oxygen from the atmosphere for respiration. In mammals, the respiratory epithelium is equipped with important immune defenses including innate and adaptive humoral and cellular players. Allergic or Th2 responses occur in response to helminth infections or in the presence of allergens. These responses are characterized by eosinophil and mast cell infiltrations and production of immunoglobulin (Ig) E. Our hypothesis is that, the first tetrapods (lungfishes), are capable of mounting allergic immune responses in response to fungal allergens as in the case of mammals. We plan on using the African lungfish, Protopterus dolloi, to develop an allergy model in order to test this hypothesis. A customized test chamber will be used to measure metabolic rates in P. dolloi and quantify allergen uptake into the lungs during exposure to house dust mite antigen for 24 hours or 5 days. Histological samples from all lymphoid organs and spleen will be sample and infiltration of lymphoid cells analyzed by light microscopy. Additionally, expression of immune relevant genes related to canonical mammalian Th2 responses will be evaluated. Since lungfish only posses IgM, IgW short and IgW long, these experiments will reveal if other immunoglobulin isotypes may be responsible for allergic responses in the absence of IgE.