ALLERGIC REACTIVITY AND IGG SUBCLASSES TO A PROTEINASE FRACTION OF SETARIA-DIGITATA IN FILARIASIS

A low molecular weight fraction (30 KDa) of the cattle filarial parasi te Setaria digitata that was earlier demonstrated to have allergenic a ctivity was characterized to be a zinc-dependent cysteine proteinase. Immediate type hypersensitivity (ITH) reaction to the proteinase was e valuated in lymphatic filariasis patients and in endemic controls from Orissa, India. The extent of ITH positivity to the proteinase in infe cted individuals ranged from 20% in chronic filariasis (CP) patients g roup to 56% in asymptomatic microfilaraemic carriers (AS). About 62% o f endemic normals (EN) were also ITH positive. The serum levels of IgG subclasses were compared in ITH positive and ITH negative filarial pa tients (AS and CP) as well as in endemic normals (EN) respectively. Ig G, levels were found to be inversely dependent on ITH reaction only in AS groups. Asymptomatic patients (AS) with positive ITH reactivity ha d lower IgG, than ITH negative individuals from the same group. The se rum levels of other IgG subclasses except IgG, did not correlate with ITH reactivity. IgG, levels were higher in ITH negative EN and CP pati ents but not in the AS group.