%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Turner, J. D.
%A Faulkner, H.
%A Kamgno, J.
%A Kennedy, M. W.
%A Behnke, J.
%A Boussinesq, M.
%A Bradley, J. E.
%T Allergen-specific IgE and IgG4 are markers of resistance and susceptibility in a human intestinal nematode infection
%D 2005
%L PAR00000409
%G ENG
%J Microbes and Infection
%@ 1286-4579
%K IgE ; IgG4 ; allergen ; helminth ; immunity ; Th2
%M CC:0002309792-0004
%N 7-8
%P 990-996
%R 10.1016/j.micinf.2005.03.036
%U https://www.documentation.ird.fr/hor/PAR00000409
%V 7
%W Horizon (IRD)
%X IgG4 has been proposed to act as a 'blocking antibody' due to its ability to compete for the same epitopes as IgE thus preventing IgE-dependent allergic responses. IgG4 and IgE are both elevated in helminth infections and strong anti-parasite IgE responses are associated with resistance to infection. We wished to determine the relationship between anti-parasite IgG4 and IgE and Ascaris lumbricoides infection status. We examined anti-parasite responses, including antibody levels to recombinant Ascaris allergen-1A (rABA-1A), a target of serum IgE in endemic populations. Worm burden was indirectly estimated by measuring parasite egg output in a cross-sectional human population (N = 105). Levels of anti-parasite IgG4 and IgE in patients' plasma were quantified by immunoassay. Global anti-parasite antibody responses did not bear any significant relationships with intensity of Ascaris infection. Individuals who had detectable levels of IgE but not IgG4 to rABA-1A (11%) had lower average levels of infection compared with individuals who produced anti-rABA-1A IgG4 (40%) and sero-negative individuals (49%) (P = 0.008). The ratio of IgG4/IgE in rABA-1A responders positively correlated with intensity of infection (P < 0.025). IgG4 levels positively correlated with infection level in younger children (age 4-11) where average levels of infection were increasing (P = 0.038), whereas allergen specific IgE emerged as a correlate of immunity in older children and adults (age 12-36) where infection levels were decreasing (P = 0.048). Therefore, in a gastrointestinal helminth infection, differential regulation of anti-allergen antibody isotypes relate to infection level. Our results are consistent with the concept that IgG4 antibody can block IgE-mediated immunity and therefore allergic processes in humans. (c) 2005 Elsevier SAS. All rights reserved.