Cytokine Production by Lymph Node Cells from Mice Infested with Ixodes ricinus Ticks and the Effect of Tick Salivary Gland Extracts on IL-2 Production

In BALB/c mice repeatedly infested with nymphal Ixodes ricinus ticks, lymphocytes from axillary and brachial lymph nodes which drain the tick attachment site produced significant levels of IL-2, TNF-α and GM-CSF when stimulated in vitro with Con A or anti-CD3 antibodies. Cytokine production by cells from lymph nodes of the opposite flank was equivalent to that of cells from uninfested mice. Nine days after the first infestation and IL-2, GM-CSF were produced primarily by the CD4⁺ T cells, while some other cell types contributed also to the TNF-α production. In mice repeatedly infested, a gradual increase of lymph node cell production of IL-2 was observed. The IL-2 levels regularly increased from the first to the third infestation compared to TNF-α levels which gradually decreased. The in vitro production of GM-CSF was not affected by successive infestations. Spleen lymphocytes from naive mice produced higher levels of IL-2 than lymphocytes from axillary and brachial lymph nodes. Both tick salivary gland extracts and D-mannose inhibited IL-2 production by these lymphocytes.