CD4⁺ T cell responses did not show a specific signature following re-challenge with the homologous <i>C. jejuni</i> strain.

<p>The effect of challenge on <i>C. jejuni</i> veterans shows a diverse T cell profile compared to naïve subjects. Eight subjects were re-dosed with the homologous <i>C. jejuni</i> CG8421 strain three months after initial infection. We examined CD4⁺ T cell responses for the production of IFNγ⁺, TNFα⁺, IL-2⁺, and MIP-1β at multiple timepoints pre- and post-re-infection. Responses shown are the percentage of cytokine positive CD4⁺ T cells from CAg-stimulated PBMCs with the background percentage of cytokine-positive T cells in the negative control (PBS) subtracted. D98 represents PBMCs from a blood drawn prior to re-infection. Bars represent percent of CD4⁺ T cells detected on specific days: D98 (day of re-dosing, yellow); D105 (blue); D112 (red); and D126 (black). No significant changes were observed post re-challenge compared to D98.