Cell-Mediated Response to Tetanus Toxoid
Cytokine Production and the T-helper Response
To investigate the mucosal cellular response, CD4+ cells from the small intestine were isolated from each group and stained for intracellular cytokines. Seven days after immunization, there were significantly higher amounts of IL-4, IL-5, IL-10, and IFN- γ present in the vaccinated group than in the control group. These levels were still elevated at day 42, with a much higher proportion of IL-4 being produced (Figure 1). It appears that a mixed Th1/Th2 response was elicited, with a slight bias towards the Th2 response.
In an additional experiment by Robinson et al. (2004), mice were immunized intraperitoneally with either TT-expressing L. lactis or a vaccine consisting of TT and Freund’s complete adjuvant (TT-FCA). It was found that splenocytes from the TT-plasmid group produced significantly higher levels of IL-4 than the control group (suggesting a Th2 response), but the group vaccinated with TT-FCA produced significantly higher levels of IFN-γ (suggesting a Th1 response).
Can Adjuvants Polarize the T-helper Response?
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