The number of OF-specific IFN-γ secreting mononuclear cells/100 000 lymphocytes, detected with the ELISPOT assay, before and after treatment with Doxycycline and Placebo. The graph illustrates cytokine data from the first nine included patients. The OF-specific cytokine secretion was obtained by subtracting the number of spots in unstimulated (spontaneous) wells from the number of spots in OF-stimulated wells, illustrating the Borrelia-specific memory immune response. Values, which represent medians of triplicates, are given as number of cytokine secreting cells/100 000 lymphocytes. The dotted horizontal line indicates the cut-off (= 15 cells/100 000) for OF-specific IFN-γ secretion. No significant differences in change of the number of cytokine secreting cells were found either within or between the two treatment groups. Horizontal lines denote the median. Abbreviations: OF, outer surface protein–enriched fraction of B. garinii strain Ip90; IFN, interferon; ELISPOT; enzyme-linked immunospot assay.