title: Human cellular immune response against Giardia lamblia 5 years after acute giardiasis.
abstract: BACKGROUND
  Clinical and epidemiological studies have suggested the development of acquired immunity in individuals previously infected with Giardia lamblia. However, there are no data on the long-term cellular immunity and genotype cross-reactivity. An outbreak of assemblage B giardiasis in a nonendemic area made it possible to evaluate the long-term cellular mediated immunity and its specificity toward the 2 Giardia assemblages known to infect humans.
  
  
  METHODS
  Peripheral blood mononuclear cells from 19 individuals infected with Giardia assemblage B 5 years previously and from 10 uninfected controls were cultured with antigens from assemblage A and B Giardia trophozoites for 6 days. Cell-mediated immunity was measured by a (3)H-thymidine proliferation assay and flow cytometric analysis of activation markers HLA-DR, CD45RO, CD25, and CD26 in T-cell subsets.
  
  
  RESULTS
  Proliferation responses were significantly elevated in the group previously exposed to Giardia for nearly all Giardia antigens tested. Individual responses toward Giardia trophozoite whole cell, cytosolic, and excretory-secretory antigens from both assemblages correlated well. Activation marker responses were mainly seen in CD4 T cells.
  
  
  CONCLUSIONS
  G. lamblia infection induces long-term, albeit variable, cellular immune responses that are not assemblage specific and that are largely driven by CD4 T-cell activation.
authors: Institute of Medicine, University of Bergen, Bergen, Norway. kurt.hanevik@med.uib.no
authors: Kurt
authors: K
authors: Hanevik
authors: Einar
authors: E
authors: Kristoffersen
authors: Staffan
authors: S
authors: Svard
authors: Oystein
authors: O
authors: Bruserud
authors: Emma
authors: E
authors: Ringqvist
authors: Steinar
authors: S
authors: Sørnes
authors: Nina
authors: N
authors: Langeland
mesh_terms: D000328:Adult; D000953:Antigens, Protozoan / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D016829:Giardia lamblia / Q000235:genetics / Q000276:immunology*; D005873:Giardiasis / Q000276:immunology*; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009664:Norway
chemical_list: D000953:Antigens, Protozoan; D006684:HLA-DR Antigens; D053645:Interleukin-2 Receptor alpha Subunit; D017493:Leukocyte Common Antigens; D018819:Dipeptidyl Peptidase 4