title: Life history, immune function, and intestinal helminths: Trade-offs among immunoglobulin E, C-reactive protein, and growth in an Amazonian population.
abstract: OBJECTIVE
  Infection with helminths is associated with shifts in host immunity, including increased production of immunoglobulin E (IgE) and reduced inflammation. Given limited energy budgets, these shifts may involve changes in energy allocation toward competing demands. Here we test for potential trade-offs between growth, IgE, and the inflammatory marker C-reactive protein (CRP).
  
  
  METHODS
  Dried blood spots and anthropometrics were collected from 162 Shuar forager-horticulturalists from a village in southeastern Ecuador. Enzyme-linked immunosorbent assays (ELISAs) were used to measure IgE and CRP. Relationships among IgE, CRP, and anthropometrics were examined in three groups: children aged 2-7 years (n = 63), children aged 8-15 (n = 61), and adults over age 18 (n = 37).
  
  
  RESULTS
  Geometric mean IgE was 1,196 IU ml⁻¹ while geometric mean CRP was 1.33 mg l⁻¹. In children, IgE and CRP were negatively correlated (r = -0.21, P = 0.02, df = 122). Controlling for fat stores and age, IgE was associated with lower stature in children (t = -2.04, P = 0.04, df = 109), and adults (t = -3.29, P < 0.01, df = 33). In children there was a significant interaction between age and CRP, such that in younger children CRP was associated with shorter stature, but in older children was associated with greater stature (t = 2.15, P = 0.04, df = 109).
  
  
  CONCLUSIONS
  These results suggest that infection with helminths may have hidden costs associated with immunological changes, and that these costs may ultimately affect growth and other life history parameters.
authors.affiliation: Integrative Anthropological Sciences, University of California, Santa Barbara, California 93106-3210, USA. ablackwell@isber.ucsb.edu
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Blackwell
authors.forename: J Josh
authors.initials: JJ
authors.lastname: Snodgrass
authors.forename: Felicia C
authors.initials: FC
authors.lastname: Madimenos
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Sugiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D001837:Body Weights and Measures; D002097:C-Reactive Protein / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D004484:Ecuador / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006128:Growth / Q000502:physiology*; D006306:Health Surveys; D006373:Helminthiasis / Q000150:complications* / Q000208:ethnology / Q000276:immunology; D006801:Humans; D007109:Immunity; D007073:Immunoglobulin E / Q000097:blood*; D007199:Indians, South American; D008297:Male
chemical_list: D007073:Immunoglobulin E; D002097:C-Reactive Protein