title: Necator americanus and helminth co-infections: further down-modulation of hookworm-specific type 1 immune responses.
abstract: BACKGROUND
  Helminth co-infection in humans is common in tropical regions of the world where transmission of soil-transmitted helminths such as Ascaris lumbricoides, Trichuris trichiura, and the hookworms Necator americanus and Ancylostoma duodenale as well as other helminths such as Schistosoma mansoni often occur simultaneously.
  
  
  METHODS
  We investigated whether co-infection with another helminth(s) altered the human immune response to crude antigen extracts from either different stages of N. americanus infection (infective third stage or adult) or different crude antigen extract preparations (adult somatic and adult excretory/secretory). Using these antigens, we compared the cellular and humoral immune responses of individuals mono-infected with hookworm (N. americanus) and individuals co-infected with hookworm and other helminth infections, namely co-infection with either A. lumbricoides, Schistosoma mansoni, or both. Immunological variables were compared between hookworm infection group (mono- versus co-infected) by bootstrap, and principal component analysis (PCA) was used as a data reduction method.
  
  
  CONCLUSIONS
  Contrary to several animal studies of helminth co-infection, we found that co-infected individuals had a further downmodulated Th1 cytokine response (e.g., reduced INF-γ), accompanied by a significant increase in the hookworm-specific humoral immune response (e.g. higher levels of IgE or IgG4 to crude antigen extracts) compared with mono- infected individuals. Neither of these changes was associated with a reduction of hookworm infection intensity in helminth co-infected individuals. From the standpoint of hookworm vaccine development, these results are relevant; i.e., the specific immune response to hookworm vaccine antigens might be altered by infection with another helminth.
authors: Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil. stefan@cpqrr.fiocruz.br
authors: Stefan Michael
authors: SM
authors: Geiger
authors: Neal Douglas Edward
authors: ND
authors: Alexander
authors: Ricardo Toshio
authors: RT
authors: Fujiwara
authors: Simon
authors: S
authors: Brooker
authors: Bonnie
authors: B
authors: Cundill
authors: David Joseph
authors: DJ
authors: Diemert
authors: Rodrigo
authors: R
authors: Correa-Oliveira
authors: Jeffrey Michael
authors: JM
authors: Bethony
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D000947:Antigens, Helminth; D001196:Ascariasis / Q000276:immunology* / Q000469:parasitology; D017164:Ascaris lumbricoides / Q000276:immunology; D002648:Child; D060085:Coinfection / Q000276:immunology* / Q000469:parasitology; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D017221:Necator americanus / Q000276:immunology*; D009332:Necatoriasis / Q000276:immunology* / Q000469:parasitology; D012550:Schistosoma mansoni / Q000276:immunology; D012555:Schistosomiasis mansoni / Q000276:immunology* / Q000469:parasitology; D055815:Young Adult
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D007074:Immunoglobulin G; D007073:Immunoglobulin E; D007371:Interferon-gamma