Decreased atopy in children infected with Schistosoma haematobium: a role for parasite-induced interleukin-10.
BACKGROUND
Most of the effort directed at understanding the role infections have in preventing allergy has focused on bacteria and viruses and their ability to divert the immune system towards T-helper-1 responses and away from proallergic T-helper-2 responses. However, helminth infections, highly prevalent in large parts of the developing world, where allergy is uncommon, stimulate strong T-helper-2 responses. We investigated the influence of chronic helminth infections on the prevalence of atopy and aimed to understand the relation at a detailed immunological level.


METHODS
520 Gabonese schoolchildren were tested for skin reaction to house-dust mite and other allergens, for Schistosoma haematobium eggs in urine, and for microfilariae in blood samples. Total and mite-specific IgE antibodies were measured. A subsample selected on the basis of their skin test to house-dust mite received detailed immunological investigations.


RESULTS
Children with urinary schistosomiasis had a lower prevalence of a positive skin reaction to house-dust mite than those free of this infection (odds ratio 0.32 [95% CI 0.16-0.63]). The degree of sensitisation to house-dust mite could not explain this difference in skin-prick positivity. Schistosome-antigen-specific concentrations of interleukin-10 were significantly higher in infected children, and higher specific concentrations of this anti-inflammatory cytokine were negatively associated with the outcome of skin-test reactivity to mite (0.53 [0.30-0.96]). No association between polyclonal IgE antibodies and skin-test results was found.


CONCLUSIONS
The anti-inflammatory cytokine, interleukin-10, induced in chronic schistosomiasis, appears central to suppressing atopy in African children.
van den Biggelaar
A H
AH
Department of Parasitology, Leiden University Medical Centre, The Netherlands.
van Ree
R
R
Rodrigues
L C
LC
Lell
B
B
Deelder
A M
AM
Kremsner
P G
PG
Yazdanbakhsh
M
M
D000293:Adolescent; D000485:Allergens / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides; D002648:Child; D002675:Child, Preschool; D005260:Female; D005681:Gabon / Q000453:epidemiology; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood; D016753:Interleukin-10 / Q000378:metabolism; D008297:Male; D008925:Mites / Q000276:immunology; D015995:Prevalence; D012548:Schistosoma haematobium / Q000302:isolation & purification* / Q000502:physiology; D012553:Schistosomiasis haematobia / Q000276:immunology* / Q000378:metabolism; D012882:Skin Tests
D000485:Allergens; D039741:Antigens, Dermatophagoides; D006023:Glycoproteins; D016753:Interleukin-10; D007073:Immunoglobulin E