Deficient transendothelial migration of leukocytes in Q fever: the role played by interleukin-10.

Chronic Q fever is characterized by deficient cell-mediated immune response, lack of granulomas, and dysregulation of the cytokine network. Altered transendothelial migration (TM) of peripheral-blood mononuclear cells might account for impaired immune response. TM of lymphocytes and monocytes was decreased in patients with Q fever endocarditis, compared with that in patients recovering from acute Q fever and in control subjects. This defect is related to interleukin (IL)-10, a cytokine involved in the chronic evolution of the disease; neutralizing anti-IL-10 antibodies corrected TM of mononuclear cells from patients with Q fever endocarditis. IL-10 may account for deficient protective immunity in patients with Q fever endocarditis by impairing TM.