In order to investigate the preventive and therapeutic effects of Herba Houttuyniae extract (H. H. ext.) on pneumonitis bearing mice, pneumonitis bearing mice induced by Klebsiella pneumoniae (K. pneumoniae) were established by the determination of median lethal dose(LD_50)of H.H.ext.. pathogenicity of K. pneumoniae in vivo, and minimum inhibition concentration(MIC) of H.H.ext, in vitro was performed on microorganism. Then, these experiments were performed to investigate the effects of H.H.ext. in mice, and they were delayed type hypersensitivity (DTH), antibody production to sheep erythroctes, rosette formation, natural killer(NK) cell activity of splenic lymphocyte population and histological findings with passage of time. Mice intranasally inoculated with 1×10^6 K.pneumoniae under light ether anesthesia were intravenously sensitized by 1×10^7 SRBC suspension.
The results were as follows :
1. The LD_50 of H.H.ext. was orally 0.5g/㎏.
2. The MIC of H.H.ext. by water and ethanol was as flollows :
In K. pneumoniae, MIC was 16㎎/㎖ in each case of stem and leaf, root extracted by water, and herb extracted by ethanol. But herb extracted by water was 32㎎/㎖.
In Sta. aureus, MIC was 140㎎/㎖ in stem and leaf, herb extracted by water, but root was 160㎎/㎖. And herb extracted by ethanol was 128㎎/㎖.
In Sta. pyogenes, MIC was 32㎎/㎖ regardless of water and ethanol.
In E. coli, MIC was 128㎎/㎖ by water, but 64㎎/㎖ by ethanol.
3. Optimal dosage of pneumonitis induced by K.pneumoniae was 1×10^8 CFU/mouse in mouse model.
4. Comparing with normal control group, DTH reaction was significantly increased in Group 1 and 5 (P<0.05, P<0.01).
5. Hemagglutination and hemolysin titers of each experimental groups were variable, not significant against control group.
6. E rosette formation rate of spleen cells was significantly increased in Group 1, 2 and 5(P<0.05), but was decreased in Group 3 and 4.
7. NK cell activity of spleen cells was not significant between control and experimental groups. But Group 1 was gradually increased with the passage of time. Also NK cell activity of Group 2, 3 and 4 was transiently increased at the first week.
8. Typical peumonitic process was observed in Group 4 only, but mild pneumonitic process or curring process was observed in Group 1, 2 and 3. Group 5 only showed no evidence of inflammatory reaction. However, mild infiltration of lymphoidcells was noted in early stage.
From these results, it is suggested that H.H.ext promotes immune response and reduces the recovery time of pneumonitis and lung abscess from the histological viewpoint.
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