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Requirements for in vivo IFN-induction by live microfilariae of the parasitic nematode, Brugia malayi

Summary: 631
Requirements for in vivo IFN- induction by live
microfilariae of the parasitic nematode, Brugia malayi
R. A. LAWRENCE"*, J. E. ALLEN# and C. A. GRAY"
" Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street,
London WC1E 7HT
# Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT,
(Received 14 October 1999; revised 7 January 2000; accepted 8 January 2000)
Lymphatic filariasis caused by the parasitic nematode, Brugia malayi, is a chronic human disease immunologically
characterized by stimulation of Th2 cells and reduced antigen-specific T cell responses. Single stage intra-peritoneal
infections with infective larvae (L3) or adult nematodes induce Th2 cells, while the microfilarial stage (Mf) stimulates
IFN- and Mf-specific IgG1, IgG2a, IgG2b, IgG3 and IgM, but not IgE. To investigate whether IFN- is elicited by
live Mf in their natural site of infection, mice were infected intravenously. Intravenous infection had a striking effect on
the response to Mf and high levels of IgE were induced even in the presence of IFN-. Indeed IgE levels to Mf increased
markedly with the number of immunizations, higher doses of Mf and prolonged exposure to Mf suggesting that under
conditions of chronic antigen exposure, typical of human disease, Mf will stimulate high levels of IgE. The ability of Mf-
induced IFN- to modulate or regulate a pre-existing Th2 response, was investigated by infecting mice initially with adult
male worms to induce a Th2 response, followed 14 days later by infection with Mf. Although Mf stimulated IFN- in


Source: Allen, Judith - School of Biological Sciences, University of Edinburgh


Collections: Biology and Medicine