Interleukin 17 producing T cell responses in human chronic trichinellosis-insight from a case study

We studied the cellular immune response in a patient infected since 10 months (along with other 51 people) during a trichinellosis outbreak caused by Trichinella spp.

A 46 years old female resulted serologically positive for trichinellosis. We isolated peripheral blood mononuclear cells (PBMCs) and incubated them with excretory/secretory antigens (ESA) of Trichinella spiralis (T1) or Trichinella pseudospiralis (T4) to produce antigen specific T cell lines and clones, analysed for the phenotype (T helper or cytotoxic cells), for their T4 or T1 antigens specificity and for their cytokine profile (IFNγ, IL-17A, IL-4) by flow cytometry, thymidine incorporation assay and ELISpot.

The test performed using ESA from T1 or T4 has identified the species responsible for infection as T. pseudospiralis since the proliferative responses (evaluated by CFSE, Carboxyfluorescein succinimidyl ester, FACS analysis) was higher for T4 (72,8%) than T1 (23.6 %) antigen. The cell lines produced significant levels of IFNγ, IL-4 and IL-17A after stimulation. From the T cell line obtained in response to T1 ESA, as regards CD4 + cells, 12 % Th2, 22.8 % Th1, 6.6 % Th17, 6 % Th0, 2.2 % Th1/Th17 and 0.7 % Th2/Th17, were obtained. From the T1-specific TCL we generated 15 clones. From the TCL specific for T4 ESA, as regards CD4+, 15.2 % Th2, 27.1 % Th1, 3 % Th17, 10.3 %Th0, 1.9 % Th1/Th17 and 1 % Th2/ Th17 were obtained. From such TCL 4 clones were isolated, 1Th2, 1 Th1, 1 Th17, 1 Th1/Th17 and no Th0 nor Th2/Th17.

By cellular immunology techniques the species responsible of the infection resulted T. pseudospiralis, confirming the results previously obtained by serology. For the first time it was revealed in a human chronic infection the presence of Th17 cells.