Identification and Characterization of a Novel Nematode Pan Allergen (NPA) from Wuchereria bancrofti and their Potential Role in Human Filarial Tropical Pulmonary Eosinophilia (TPE)

Tropical pulmonary eosinophilia (TPE) is a chronic respiratory syndrome associated with Lymphatic Filariasis (LF), a tropical parasitic infection of the human, transmitted by mosquitoes. A larval form of LF, the microfilariae trapped in the lungs of TPE subjects have a major role in initiating the TPE syndrome. To date, there are no reports on the potential allergen that is responsible for generating parasite-specific IgE in TPE. In this project, we screened a cDNA expression library of the microfilarial stages of Wuchereria bancrofti with monoclonal IgE antibodies prepared from subjects with clinical filarial infections. Our studies identified a novel molecule that showed significant sequence similarity to an allergen. A blast analysis showed the presence of similar proteins in a number of nematodes parasites. Thus, we named the molecule as Nematode Pan Allergen (NPA). Subsequent functional analysis showed that NPA is a potent allergen that can cause release of histamine from mast cells, induce secretion of proinflammatory cytokines from alveolar macrophages and promote accumulation of eosinophils, all of which occur in TPE lungs. Therefore, we believe that NPA may have a significant role in the pathology of the TPE syndrome.