Differential antibody response to parasite lipid antigens in lymphatic filariasis

摘要

Antibody response to lipid antigens from microfilariae of cattle filarial parasite Setaria digitata was evaluated in human filarial sera of Orissa, India. Increased antibody (IgG and IgM) levels were observed in amicro-filaraemic groups of chronic patients and endemic normals compared to microfilaraemic carriers. Antibody levels were negligible in people living in nonfilarial regions and in leprosy patients suggesting filariae specificity, Anti-lipid antibodies were also found to be considerably elevated in Brugia malayi (L-3)-infected mastomys without microfilaraemia than in those animals with microfilariae, These data indicate that high antibody levels to lipid antigens are associated with microfilariae negativity. Ige subclass analysis revealed the predominance of IgG(2) in asymptomatic microfilaraemics IgG(3) and IgG(1) in chronic patients and IgG(1) end IgG(2) in endemic normals. Diethylcarbamazine treatment in asymptomatic microfilaraemic subjects led to enhanced antibody response that sustained more than six months post treatment. The nature of antigenic determinant recognized by filarial antibodies was assessed by periodate treatment and indicated these antigens to be glycolipids, Periodate oxidation of lipids resulted in an overall decrease in antibody binding, the magnitude of which varied depending on antibody isotypes and filarial groups. The periodate-sensitive carbohydrate epitopes were recognized by both IgG and IgM in asymptomatic microfilaraemic carrier sera, but only by IgG in endemic normals and chronic filarial sera; IgM binding in the latter sera remained unaffected. Carbohydrate recognition by filarial antibodies seems to be dissimilar in different clinical groups of filariasis and might modulate the course of filarial infection in humans. [References: 21]