Interleukin-5 is essential for vaccine-mediated immunity but not innate resistance to a filarial parasite.
The study of protective immune mechanisms effective against filarial nematodes has been hampered by the inability of these important human pathogens to infect laboratory mice. Recently, Litomosoides sigmodontis, a natural parasite of rats, has been developed as a valuable model for the study of filarial infection. BALB/c mice are fully susceptible to infection with L. sigmodontis third-stage larvae and develop patent infection. In contrast, mice on the C57BL background are resistant, and parasites undergo only a single molt and do not mature to adulthood. We used interleukin-5 (IL-5)-deficient mice on the C57BL/6 background to address the role of IL-5 and eosinophils in the innate resistance of C57BL/6 mice. We found no differences in parasite survival between IL-5-deficient and C57BL/6 mice. However, when these mice were used for the analysis of vaccine-mediated immunity, a critical role for IL-5 was elucidated. Mice genetically deficient in IL-5 were unable to generate a protective immune response when vaccinated with irradiated larvae, whereas C57BL/6 mice were fully protected from challenge infection. These studies help to clarify the highly controversial role of eosinophils in filarial infection.
Le Goff
L
L
Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom.
Loke
P
P
Ali
H F
HF
Taylor
D W
DW
Allen
J E
JE
D000818:Animals; D005368:Filariasis / Q000276:immunology*; D005370:Filarioidea; D007113:Immunity, Innate / Q000276:immunology; D015848:Interleukin-5 / Q000235:genetics / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D014612:Vaccines / Q000276:immunology*
D015848:Interleukin-5; D014612:Vaccines