Figure 1.
Prior bacillus Calmette Guérin (BCG) infection inhibited ovalbumin (OVA)-specific immunoglobulin E (IgE) production. Data from two independent experiments are shown. C57BL/6 mice were infected intravenously with 1×105 (a) or 1×106 (b) colony-forming units (CFUs) of Mycobacterium bovis BCG or treated with phosphate-buffered saline (PBS) alone. Two weeks after BCG inoculation, mice were immunized intraperitoneally with 2 μg of OVA in 2 mg of Al(OH)3 (alum) adjuvant. Mice were bled at day 10 postimmunization for analysis of serum IgE production. Allergen (OVA)-specific IgE levels in individual mice were determined by passive cutaneous anaphylaxis (PCA) using female Sprague-Dawley rats. Geometric mean titres (±SEM) of each group, plotted on a log2 scale, are presented. *represents P<0·05.