title: IL-12, IFN-gamma, and T cell proliferation to measles in immunized infants.
abstract: Measles infection in infants is associated with severe complications, and secondary infections are attributed to generalized immunosuppression. Measles binding to its monocyte receptor down-regulates IL-12 which is expected to diminish Th1-like cytokine responses, including IFN-gamma. Whether young infants can be immunized effectively against measles is an important public health issue. We evaluated Ag-specific IL-12, IFN-gamma, and T cell responses of infants at 6 (n = 60), 9 (n = 46), or 12 mo (n = 56) of age and 29 vaccinated adults. IL-12 and IFN-gamma release by PBMC stimulated with measles Ag increased significantly after measles immunization in infants. IL-12 and IFN-gamma concentrations were equivalent in younger and older infants, but IL-12 concentrations were significantly lower in infants than in adults (p = 0.04). IL-12 production by monocytes was down-regulated by measles; the addition of recombinant human IL-12 enhanced IFN-gamma production by PBMC stimulated with measles Ag, but infant T cells released significantly less IFN-gamma than adult T cells under this condition. Of particular interest, the presence of passive Abs to measles had no effect on the specific T cell proliferation or IFN-gamma production after measles stimulation. Cellular immunity to measles infection and vaccination may be limited in infants compared with adults as a result of less effective IFN-gamma and IL-12 production in response to measles Ags. These effects were not exaggerated in younger infants compared with effects in infants who were immunized at 12 mo. In summary, infant T cells were primed with measles Ag despite the presence of passive Abs, but their adaptive immune responses were limited compared with those of adults.
authors.affiliation: Infectious Diseases Division, Department of Pediatrics, Stanford University School of Medicine, CA 94305, USA. hagans@stanford.edu
authors.forename: H A
authors.initials: HA
authors.lastname: Gans
authors.forename: Y
authors.initials: Y
authors.lastname: Maldonado
authors.forename: L L
authors.initials: LL
authors.lastname: Yasukawa
authors.forename: J
authors.initials: J
authors.lastname: Beeler
authors.forename: S
authors.initials: S
authors.lastname: Audet
authors.forename: M M
authors.initials: MM
authors.lastname: Rinki
authors.forename: R
authors.initials: R
authors.lastname: DeHovitz
authors.forename: A M
authors.initials: AM
authors.lastname: Arvin
mesh_terms: D000328:Adult; D000367:Age Factors; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000502:physiology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007223:Infant; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D008458:Measles Vaccine / Q000276:immunology* / Q000494:pharmacology; D009000:Monocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology; D009500:Neutralization Tests; D010835:Phytohemagglutinins / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology / Q000494:pharmacology
chemical_list: D000914:Antibodies, Viral; D018984:Epitopes, T-Lymphocyte; D008458:Measles Vaccine; D010835:Phytohemagglutinins; D011994:Recombinant Proteins; D014613:Vaccines, Attenuated; D018664:Interleukin-12; D007371:Interferon-gamma