Both FHA and PT were able to elicit a T cell response in vitro in a subset of the vaccinated children, by measuring the frequency of CFSEdim cells (Supplementary Figure 2C, green gate). For the proliferation of CD4+ T cells, the response to FHA was significantly higher from that of unstimulated controls, both for wP-

and aP-vaccinated children (Wilcoxon signed rank test, p < 0.05 and p < 0.01) ( Fig. 1A and B). For the CD8+ T cells, in addition to a significant proliferation in response to FHA both in wP- and aP-vaccinated children (p < 0.01), a response to PT was observed for wP-vaccinated children (p < 0.05) ( Fig. 1C and D). These results indicated Trametinib nmr that, although the time since the last booster vaccine was see more significantly longer for wP- compared to aP-vaccinated children, the proliferation capacity of wP-vaccinated children in response to antigenic stimulation was at least as good as the response observed for aP-vaccinated children. Globally, the majority of the children were able to respond by CD4+ T cell proliferation to at least one of the tested Bp antigens (79%, see Section 2.4 for definition of responder), while 60% of them responded by CD8+ T cell proliferation

( Table 1). We compared Bp-specific cytokine responses of wP- and aP-vaccinated children. The nonspecific background was determined by culturing the PBMC from the same subject, for the same period in the absence of antigen, and all results are background subtracted. The frequency of CD4+ cells producing IFN-γ TCL in response to FHA was significantly higher for wP-compared to aP-vaccinated children (Mann–Whitney, p < 0.01), while this difference was not significant for PT ( Fig. 2A). Antigen-specific production of TNF-α was also noted for a subset of vaccinated children

but no significant differences appeared between wP- and aP-vaccinated children ( Fig. 2B). Globally, cytokine production of CD4+ T cells in response to at least 1 antigen (FHA and/or PT) was detected in 65% (IFN-γ) and 53% (TNF-α) of the children (see Section 2.4 for definition of a responder). The frequencies of cytokine producing CD8+ T cells were low as illustrated in Fig. 2C for IFN-γ, so that classification of the subjects in responders and non-responders was not possible. When the two vaccine types were compared for their capacity to induce cytokine production in response to one or both Bp-antigens, half of the aP-vaccinated children appeared to be unable to induce a cytokine response to any antigen, in contrast to only 12% for wP-vaccinated children ( Fig. 3). Due to small sample size, no statistical analysis was performed. If a child was considered responsive to an antigen when either proliferation or cytokine production was positive, 75% and 57% of the children were responsive to FHA and PT, respectively.