Interleukin-12 in Human Boutonneuse Fever Caused by Rickettsia conorii

Interleukin (IL)-12 contributes to the resistance against a number of intracellular pathogens. We examined the potential biological role of IL-12 by studying peripheral blood mononuclear cells (PBMC), its production and its effect on cytokine synthesis in 20 Sicilian patients with boutonneuse fever (BF) caused by Rickettsia conorii. Data indicate that PBMC from acute BF patients were able to produce IL-12 in response to in vitro stimulation with rickettsial antigen (Ag): this production was higher than that detected in healed patients. Monocytes were the main source of IL-12 by PBMC from BF patients. IL-12 secretion by in vitro Ag-stimulated PBMC from BF patients was potentiated by recombin…