Cellular responses and cytokine profiles in Ascaris lumbricoides and Trichuris trichiura infected patients

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Abstract
The impact of intestinal helminth infection, i.e. Ascaris lumbricoides and Trichuris trichiura, on cellular responsiveness and cytokine production was investigated in young adults. Ascaris‐specific cellular responsiveness was higher in parasite‐free endemic controls than in patients infected with T. trichiura, or A. lumbricoides, or patients co‐infected with both parasites. Also, mitogen‐induced tumour necrosis factor (TNF)‐α, interleukin (IL)‐12 and interferon (IFN)‐γ secretion by peripheral blood mononuclear cells (PBMC) was higher in negative endemic controls than in infected individuals. Ascaris antigen‐specific production of TNF‐α, IL‐12 and IFN‐γ was low in singly Ascaris as well as in co‐infected patients, whereas secretion of IL‐10 and IL‐13 was elevated and similarly high in all patient groups. The detection of Trichuris‐specific and Ascaris‐specific IgG4 revealed significantly higher serum antibody levels in Trichuris or Ascaris patients when compared to endemic controls (P < 0·05), whereas parasite‐specific IgE antibody levels were similarly high in infected individuals and in endemic controls. In summary, chronically infected Ascaris and Trichuris patients with a high parasite load presented reduced cellular reactivity and lower type 1 TNF‐α, IFN‐γ and IL‐12 responses when compared with endemic controls, whereas type 2 IL‐10 and IL‐13 productions were similar in all groups from the endemic area. The former may support parasite persistence, whereas substantial type 2 cytokine release may promote protective immunity, suggesting an adaptation of the host to control the parasite burden while minimizing immune‐mediated host self‐damage.