Serum cytokine profile during Mycobacterium ulcerans infection (Buruli ulcer)

Background Buruli Ulcer (BU) is a severe cutaneous and subcutaneous disease due to Mycobacterium ulcerans infection, mainly distributed in sub-Saharan Africa and tropical areas. The role of T helper (TH) cytokines in the development and clinical course of the disease has been previously studied by investigating the in vitro immune response of lymphocytes from affected patients and immunohistochemical analyses of bioptic samples. Methods TH cytokine levels (IFN gamma, TNF-alpha, IL-2, IL-10, IL-4, IL-5, IL-17) were evaluated in serum of 34 Beninese subjects by cytofluorimetric and immunoenzymatic assays: 16 patients affected with active BU, 4 patients who had healed after specific therapy, and 14 matched controls. Results Levels of IFN gamma were higher in patients with late BU (> 2 months from onset) and healed patients than in controls, and in ulcerative than in pre-ulcerative patients. Analysis of 4 patients with late disease evaluated both at the beginning of antibiotic therapy and 6 months later showed that IFN gamma levels were always lower in the second evaluation. By contrast, no differences were found in levels of the other cytokines. Conclusions IFN gamma production is low in early BU, and increases in late BU and healing, suggesting a role of this cytokine in infection clearance. Moreover, evaluation of IFN gamma serum levels may be a useful tool to monitor the immune response during the BU course.