Immunofluorescence analysis of NF-kB activation. Human macrophages were stimulated for 30 min with heat-killed lactobacillus at a MOI of 1 : 500, zymosan (positive control) or left unstimulated. (a) Nuclear translocation was defined as blue fluorescence (Hoechst staining), and the NF-kB pp65 subunit was identified using green fluorescence (Dylight 488). (b) The percentage of nuclei that were positive for pp65. The results represent three independent experiments.