Figure 4

Polyacrylamide gel electrophoresis of PCR products of bacterial 16S rDNA. Two pairs of primers were used to amplify the conserved regions. In all, 10 bacteria were used as positive controls, and 10 reactive lymph nodes as negative controls. Although the tests were done on all 24 HNLs, only parts of the data are shown here. The leftmost lane is the 20-bp marker. Lanes 1 and 2: 2 bacterial samples as positive controls. Lanes 3 and 4: 2 reactive lymph nodes as negative controls. Lanes 5–9: five cases of HNL. Note that the 1st pair of primers (upper panel) appeared to have a higher background, so that the two negative controls were weakly positive. Two HNLs were positive, but not as strongly as the positive controls. The 2nd pair (lower panel) gave a very weak background. The negative controls and the HNLs were all negative. With these two pairs of primers, only two of the 24 HNLs had a positive PCR product, making common bacteria an unlikely etiology.