ABSTRACT
The occurrence of Q fever endocarditis likely involves some alterations in the responses of monocytes, the in vivo targets of Coxiella burnetii. To test this hypothesis, the production of the inflammatory cytokines tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 was assessed in monocytes from patients with Q fever endocarditis. Spontaneous transcription and secretion of tumor necrosis factor and interleukin-1 were significantly higher in patient monocytes than in healthy controls. The interleukin-6 transcripts were also upregulated in patient cells. Moreover, in patients with recent endocarditis exhibiting high titers of immunoglobulin G directed to C. burnetii in phase I, monocytes released significantly higher levels of tumor necrosis factor and interleukin-1 than in patients with stabilized endocarditis. Immunoglobulin G titers and the overproduction of tumor necrosis factor and interleukin-1 were significantly correlated. Hence, the overproduction of inflammatory cytokines might be a marker of disease activity.
