CD4 and pertussis: To assess the quality of the pertussis-specific CD4+ T cell responses and Th subsets involved, we analyzed in a multiplex assay the concentration of various T cell cytokines in the supernatants from day 6 PBMC cultures from all participants in our clinical study (Figure 1) with S.I. ≥2 to a peptide from our Prn- or Ptx- peptide panel (Figure 4A).