Chemiluminescence and Phagocytic Activity of Murine Macrophages in Response to Various Species of Oral Bacteria

Abstract

This experiment was designed to study macrophage (MΦ) mediated phagocytic activity against periodontal pathogens in host tissue as reflected by emission of oxgen radicals. We used 9 genera, 17 species of oral bacteria, including cariogenic and periodontopathic bacteria. For the MΦ stimulation, each bacterial species was cultured in various broths, and adjusted to OD 0.3 at 540nm. Casein induced abdominal exudate MΦ from mice were used. The reaction mixture consisted of MΦ, luminol, and guinea pig complement in gelatin Hanks' solution. The chemiluminescence (CL) response was measured with a lumiphotometer (LABOSIENCE). One or two tent hs of a ml of each bacterial suspension were injected into a cuvette in which the reaction mixture had been placed. The levels of response were automatically recorded as the relative intensity of CL.
Phagocytic and lysozyme activities of MΦ in the reaction medium after CL response were also measured.
Results: the highest level of CL was shown by T. denticola. A relatively high intensity was shown by F. nucleatum and S. epidermidis. A moderate response level was shown by S. mutans, S. salivarius, S. aureus, E. faecalis and P. gingivalis. The remaining responses were low-level.
Phagocytic index and the bacterial number in 100 MΦ directed against S. mutans and S. salivarius were both high. The periodontopathic bacterial number in 100 MΦ was small, while the phagocytic index was comparatively good. There was a correlation only between CL values and the bacterial number in 100 MΦ, but this was found only in the data on Gram-positive cocci and Lactobacillus subsp.. The correlation efficiency between their values was r=0.703 (p<0.05).
Lysozyme activity released from MΦ which had not been stimulated by various kinds of bacteria revealed 40% whole cell lysozyme activity and the maximum difference corresponded to 23% of the lysozyme activity of unstimulated MΦ MΦ CL responses were decreased by 1/4 to 1/30 as compared with those of PMNs. Arranging the species in order of CL value, there was good coincidence between MΦ and PMNs, and a good correlation (r=0.840) was obtained between these two cell types.
These results suggest that the tissue damage caused by the superoxide emitted from the phagocytes, (which accumulated in the periodontal region) was less in MΦ than PMNs.