In human
filariasis, the predominant serum antibody is
IgG4, accompanied by significant
IgE production. The ratio of
IgG4 to
IgE is highest in asymptomatic microfilaremic carriers, while
chronic disease is associated with elevated IgG1-3. The changes in isotypes following
chemotherapy with
diethylcarbamazine (DEC) were studied in 2 groups of Brugia malayi-infected patients from Sumatra and South Kalimantan, Indonesia. Similar results were obtained from each group.
IgG4 levels decreased sharply (65%-78%) within 12 months.
IgG1 levels declined in a less consistent and extreme manner, and levels of
IgG2 and
IgG3 declined only in patients with
elephantiasis, who also had the highest initial levels of these
antibodies.
IgE responses were relatively stable to
therapy in microfilaremic patients (7%-28% reduction) and showed only moderate decline (56% over 2 years) in
elephantiasis patients. Active filarial
infection is thus associated with specific
IgG4 antibodies, but there is independent expression of the
IgE and
IgG4 isotypes in
filariasis.