However, very little is known of these responses shortly after booster vaccination or natural exposure in immunized children. Early measles vaccination primed IFN-γ memory T-cell responses to nucleoprotein peptides which were significantly greater at 9 months of age in immunized than unimmunized infants. However some of the unimmunized infants in group 1 had responded to these peptides suggesting that common infections such as cytomegalovirus or Epstein-Barr virus selleck chemicals llc prompt such responses [24]. At 18 and 48 months of age IFN-γ memory responses were readily detectable and similar in the two groups of children. Maternal
antibody had no effect on these responses nor were they influenced by the number of times the child had been immunized. Surprisingly ex vivo measles IFN-γ
effector responses two weeks after vaccination did not differ between those receiving primary vaccination (group 1) or secondary vaccination (group 2). After a further boost at 36 months of age effector responses to E-Z virus were similar in both groups and in neither group was there a rise after the boost. However there was a small but significant rise to fusion find more peptides which did not differ between the groups. Prime boost studies using recombinant Modified Vaccinia Ankara/TB vaccines in man [25] and DNA/measles vaccines in monkeys [17] indicate that maximum IFN-γ ELIspot responses occur 1–2 weeks after the booster immunization. Thus we are confident that the lack of a response after the booster
doses was real and not due to late sampling. However macaques primed with DNA/measles protein vaccines raise cytotoxic T-cell, IFN-γ and antibody responses within 14 days of challenge with live virus [17] and [26]. Perhaps in our study the attenuated vaccine virus did not multiply sufficiently in the presence of antibody to raise a cell mediated immune response. There were no significant Bay 11-7085 differences in plasma cytokine levels between the groups before or after the 36 month booster dose which resulted in a significant fall in IL-10, IL-2Rα and MIP-1β concentrations in both groups after the boost. This was not mirrored by changes in FOXP3 mRNA expression which were expected to increase [27]. We found no relationship between maternal or vaccine derived measles antibody concentrations and IFN-γ ELIspot numbers or cytokine levels after primary or secondary immunization. Similar findings have been noted following primary measles immunization in infants [23] or after secondary immunization in children [28] or after measles in children [29]. Intracellular cytokine staining showed that CD4 and CD8 T-cells were equally prominent producers of IFN-γ during the effector response and that both cell types a produced IL-2 in memory responses.