Salivary gland extract from Ixodes ricinus tick modulates the host immune response towards the Th2 cytokine profile.

In our previous work, the salivary gland extract (SGE) from Ixodes ricinus ticks impaired T-lymphocyte proliferation and clearly modulated the immune response towards the Th2 pattern in human peripheral blood mononuclear cell culture. In the present work, the results obtained on mouse splenocytes are compared with those on human leukocytes. ELISA (protein level) and RNAse protection assay (mRNA level) showed that SGE enhanced interleukin (IL)-1alpha, IL-1beta, IL-1Ra, IL-6, and IL-12p40 cytokines, whereas production of IL-2, IL-5, IL-10, and IL-13 was decreased. The minute levels of IL-9, IL-15 and IL-12p70 were not changed after the addition of tick saliva. IL-4 was upregulated, whereas the production of gamma interferon and migratory inhibition factor was downregulated after the addition of SGE. Tick saliva decreased concanavalin A-stimulated spleen cell proliferation and the percentage of activated T-cells. We conclude that the Th2 polarization did not involve all of the cytokines tested. However, the Th2 subset-augmenting effect of tick saliva was confirmed.