Antibody affinity in infants after immunization with conjugated capsular polysaccharide from Haemophilus influenzae type b

J Infect Dis. 1990 Nov;162(5):1185-8. doi: 10.1093/infdis/162.5.1185.


The affinities of IgG antibodies to Haemophilus influenzae b capsular polysaccharide (polyribosyl ribitol phosphate [PRP]) elicited 1 month after immunization of 47 infants 2-greater than 18 months of age with a PRP-outer membrane protein conjugate (PRP-OMP) were measured by ELISA. Thirty-four sera had affinities distributed normally about a logarithmic mean of 3.2 x 10(5) l/mol, but 13 samples had undetectable affinities (less than 10(4) l/mol). Median affinities of sera from children 2-6 (1.5 x 10(5) l/mol) and 7-11 months of age (1.6 x 10(5) l/mol) were significantly greater than the median affinities of sera from infants 12-18 (1.8 x 10(4) l/mol) or greater than 18 months of age (4.2 x 10(4) l/mol). Sera from children greater than 18 months of age vaccinated with PRP conjugated to diphtheria toxoid had a median affinity of 6.1 x 10(4) l/mol, equivalent to that of the same age group vaccinated with PRP-OMP. Children vaccinated with PRP conjugate vaccines may produce antibodies of very low affinity, a finding that may have significance for protection from invasive disease.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Antibodies, Bacterial / immunology*
  • Antibody Affinity
  • Bacterial Capsules
  • Bacterial Vaccines / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Haemophilus Vaccines*
  • Haemophilus influenzae / immunology*
  • Humans
  • Immunoglobulin G / immunology
  • Infant
  • Polysaccharides, Bacterial / immunology*
  • Radioimmunoassay


  • Antibodies, Bacterial
  • Bacterial Vaccines
  • Haemophilus Vaccines
  • Haemophilus influenzae type b polysaccharide vaccine
  • Immunoglobulin G
  • Polysaccharides, Bacterial