Serum C3d Levels in Tropical Pulmonary Eosinophilia (Report‪)‬

Tropical pulmonary eosinophilia (TPE) is an interstitial lung disease that results from an exaggerated immune response to filarial parasites Wuchereria bancrofti and Brugia malayi (1). TPE has been reported from filarial endemic regions from all over the world but is especially common in India and South East Asia (1,2). The disease is characterized by wheezing, pulmonary infiltrates and marked peripheral blood eosinophilia. Patients with TPE demonstrate very high levels of IgE and filarial specific antibodies (1-3). Studies on possible role of complement system in TPE has so far used only the classical methods like serum haemolytic component of the complement (CH50), serum C3 and C4 levels (4,5). The results so far have been inconclusive. A rise in serum C3 level was reported by some workers (4) while others observed a rise in CH50 only (5). Moreover, quantification of complement components using haemolytic or immunochemical methods does not provide dynamic information and static profiles of complement system can be misleading. Quantitation of the breakdown product of complement components was found to be the most suitable way of looking at the functioning of the complement system (6). In the present study, we determined serum levels of C3d, which is a catabolic fragment of C3, to further evaluate the possibility of the involvement of complement system in TPE. Material & Methods