Peripheral CD4⁺ T Cell cytokine responses following human challenge and Re-Challenge with campylobacter jejuni

Campylobacter jejuni is a leading cause of human gastroenteritis worldwide; however, our understanding of the human immune response to C. jejuni infection is limited. A previous human challenge model has shown that C. jejuni elicits IFNc production by peripheral blood mononuclear cells, a response associated with protection from clinical disease following reinfection. In this study, we investigate T lymphocyte profiles associated with campylobacteriosis using specimens from a new human challenge model in which C. jejuni-na?ve subjects were challenged and re-challenged with C. jejuni CG8421. Multiparameter flow cytometry was used to investigate T lymphocytes as a source of cytokines, including IFNc, and to identify cytokine patterns associated with either campylobacteriosis or protection from disease. Unexpectedly, all but one subject evaluated re-experienced campylobacteriosis after re-challenge. We show that CD4⁺ T cells make IFNγ and other pro-inflammatory cytokines in response to infection; however, multifunctional cytokine response patterns were not found. Cytokine production from peripheral CD4⁺ T cells was not enhanced following re-challenge, which may suggest deletion or tolerance. Evaluation of alternative paradigms or models is needed to better understand the immune components of protection from campylobacteriosis.