Serum cytokine profile during Mycobacterium ulcerans infection (Buruli ulcer)

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.

TH cytokine levels (IFNγ, TNF-α, 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.

Levels of IFNγ 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 IFNγ levels were always lower in the second evaluation. By contrast, no differences were found in levels of the other cytokines.

IFNγ 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 IFNγ serum levels may be a useful tool to monitor the immune response during the BU course.