1. Preparation of rabbit anti-endotoxin anti-serum.
An albino rabbit was inimunized over an 8-month period with 7 courses of
intravenous endotoxin injections into a marginal ear vein as follows: day 1, 0.25
ml: day 3, 0.5 ml; day 5, 0.75 ml; day 7, 1.0 ml; day 9, 1.25 ml; day 11, 1.5. On
day 14 after the last course, total blood was harvested from a razor-nicked ear
vein. After 2 hours at room temperature, the clot was rimmed and the blood was
refrigerated at 4℃ for 18 hours. Serum with free cells was decanted and
centrifuged at 2,000 rpm for 30 minutes at 4℃. The cell-free serum was filtered
into a sterile rubber stoppered bottle and stored at 4℃.
2. Preparation of tolerant dogs.
Endotoxin tolerant dogs were prepared according to the schedule shown in Table 2
over a 9 to 11 week period.
3. Demonstration of antibody formation in dogs.
By agar gel double diffusion method (Ouchterlony, 1958), precipitating antibody
to endotoxin was demonstrated in the serum of endotoxin tolerant animals.
4. Hemodynamic observations.
Experimental animals were divided into 4 groups and the hemodynamic changes were
observed.
Grovp Ⅰ -Tolerant dogs with purified endotoxin
Group Ⅱ -Tolerant dogs with crude endotonin
Group Ⅲ -Non-tolerant dogs with purified endotoxin
Group Ⅳ -Non-tolerant dogs with crude endotoxin
Experimental animals were anesthetized with sodium pentothal (30 mg/kg), and the
femoral artery was catheterized with a polyethylene tube which was connected to a
kymograph to record the blood pressure. At the same time electrocardiographic
findings were recorded. Purified endotoxin, 3 mg/kg, was injected intravenously in
Group Ⅰ and Group H animals, and crude endotoxin, 27.6 mg/kg, was injected
intravenously in Group Ⅱ and Group 1 animals. Again, blood pressure and
electrocardiograph were recorded with observation of animals from 2 to 5 hours.
5. Localization of endotoxin.
Tissues were obtained from the animals after hemodynamic study for localization
of endotoxin. The tissue was sectioned by cryostat 3 to 5 μ thick, and stained
with fluorescent dye by the method of Rubenstein et al. (1962).
6. Histo-pathologic observation.
With H·E stain, tissues were examined under microscope to determine whether
histologic changes, if any, and proliferation and activation of macrophages were
present.
Results
A. Detection of antibodies
1. Rabbit anti-endotcxin anti-serum.
Rabbit anti-endotoxin anti·serum was caused to react with purified endotoxin in
0.85 percent agar plate, and a single identical precipitation line was observed in
the area of rabbit anti-endotoxin anti-serum. This precipitation line was not
observed when the nonimmunized rabbit strum was used (Fig. 3). After the antibody
of rabbit anti-endotoxin anti-serum was reacted with crude endotoxin, the above
mentioned precipitation line was not observed (Fig. 4).
2. Endotoxin-tolerant serum of dogs.
Serum obtained from endotoxin tolerant dogs was made to react with endotoxin to
verify whether the serum of endotoxin tolerant dogs also produced any antibody to
endotoxin and the same precipitation line as seen in the case of rabbit
anti-endotoxin antiserum was observed. This precipitation was observed in 48 hours
when crude endotoxin was used and in 4 days when purified endotoxin used.
B. Hemodynamic changes
1. Changes of blood pressure.
When endotoxin tolerant dogs were challenged with a shock dose of endotoxin by
the intravenous route, blood pressure fell rapidly up to 15-20% of initial
pressure. About 5 minutes after endotoxin challenge, blood pressure recovered
gradually over a 2 to 5 hour period, the recovery pattern being shown in Fig. 6, 7,
8, 9. Endotoxin tolerant and non-tolerant dogs showed a similar recovery pattern of
blood pressure. However, tolerant dogs skewed very little secondary fall of blood
pressure(Fig. 6 & 7) and non-tolerant dogs did not recover from the first fall of
blood pressure (Fig. 8) or skewed a profound secondary fall of blood pressure and
this finding was core remarkable in the dogs when crude endotoxin was used (Fig.
10).
2. Electrocardiographic change.
Tolerant dogs showed no change in pulse rate or ECG tracing, but non-tolerant
dogs showed Persistent depression of S-T segments in the ECG tracing, which
suggested myocardial ischemia (Fig. 11).
C. Localization of endotoxion
A large amount of specific fluorescent material wart observed in the sinusoid,
central vein and interlobular space of liver, splenic sinusoid, and alveolar cell
of the lung. Especially, in the liver, cytoplasm of macrophages contained a large
amount of fluorescent material, and this was not observed in spleen and lung. There
was no difference in amount of fluorescent material between spleen and liver
tissue.
D. Histopathologic observation
By H-E stain, macrophages proliferated prominently in the liver of endotoxin
tolerant dogs to form granuloma which contained particulated materials which might
be hemosiderin, and this finding suggested activation of macrophages. In the liver
of the non-tolerant dogs proliferation of macrophages was not observed nor in the
spleen and Lung of the tolerant and the non-tolerant dogs.
Tissue of non·tolerant dogs challenged with a single lethal dose of endotoxin
showed no remarkable change by H-E stain.
Conclusion and Summary
1. The agar gel double diffusion method showed the presence of a specific
antibody to purified endotoxin by apperance of a single identical precipitation
line which is identical with one in rabbit anti-endotoxin anti-serum.
2. Fluorescent antibody technique demonstrated a significant amount of specific
fluorescent material in the sinusoid, central vein and interlobular space of the
liver, the sinusoid of spleen, and in the alveolar cell of lung in both tolerant
and nontolerant dogs. There observed no apparent difference in the amount of
fluorescent material of liver and spleen between the tolerant and nontolerant dogs.
3. Recovery from endotoxin shock in the hemodynamic study was far better in
tolerant dogs than in nontolerant ones, and myocardial ischemia was demonstrated by
ECG reoording in the nontolerant after endotoxin challenge.
4. Histopathologic examination of liver tissue fron tolerant dogs revealed a
feature of macrophage activation, but such a finding was not observed in the liver
from nontolerant dogs and in the spleen and lung from the tolerant and nontolerant
dogs.
[영문]
Endotoxin is a lido-polysaccharide protein complex derived from gram-negative bacteria, which can be introduced into the blood stream of the human body in various circumstances and onuses so-called "Sedotoxin shock. " Septicemia caused by gram-negative bacteria has been recognized at least since the report of Jacob
(1909) and Felty and Keefer (1924). However, septic shock was first described as a clinical entity by Waisbren (1951), and in subsequent years many experimental studies were conducted using endotoxin in dogs.
Endotoxin, given in appropriate doses to the dog, produces hypotension, rice in portal pressure with simultaneous constriction of hepatic veins, great increase in the weight of the liver, and mesenteric ischemia (Sabiston, 1972). Recently, it has been generally considered that any irreversibility of shock is a result from the insult of endotoxin (Smiddy and Fine, 1957; Fine et al., 1958; Schweinburg and Fine, 1960; Ravin et al., 1960; Sieged et al., 1967).
Beeson (1947) suggested possible tolerance to the pyrogenic effect of endotoxin, and Atkins and Wood (1955) observed that tolerant animals cleared endotoxin, which was administered intravenously, more rapidly from the blood stream, and numerous
experimental studies have been made on endotoxin shock (Dubos and Schaedler, 1956; Schweinburg et al., 1956; Smith et al., 1957; Carey et al., 1958; Freedman, 1960; Greisman et al., 1963; Rutenburg et al., 1967; Filkins and Di Luzio, 1978; Haugen,
1972; Trejo and Di Luzio, 1971).
Endotoxin tolerance is the state of enhanced resistance of animals against the toxic effects of bacterial endotoxins, and the tolerance state is usually induced by the prior administration of multiple sublethal doses of endotoxin (Beeson, 1947 ; Carey et al., 1958; Freedman, 1960; Greisman et al., 1963 ; Tsagaris et al., 1969; Trejo and Di Luzio, 1972),
Although the mechanism of endotoxin tolerance is still in controversy, it is generally thought that the endotoxin tolerance state is intimately related to phagocytic activity of the reticuloendothelial system (Good and Thomas, 1952 ; Schweinburg and Fine, 1955; Schweinburg, et al., 1955; Zweifach et al., 1957 ; Fine et al., 1958; Carey et al., 1958; Greisman et al., 1963; Arredondo and Kampschmidt, 1963 ; Filkins and Di Luzio, 1968), and, furthermore, related to the phagocytic activity of macrophages of the liver and spleen (Collins and Wood, 1959; Rutenburg et al., 1960, Cohn and Wiener, 1963; Cline et al., 1968; Filkins, 1971 ; Fine, 1972).
Tsagaris et al. (1969) demonstrated in the hemodynamic study of endotoxin shock that tolerant animals were less susceptible than the nontolerant to hemodynamic changes such as blood pressure and cardiac output, and blood pressure and cardiac output were restored more rapidly in the tolerant animals than in the nontolerant.
In mice pretreated with various agents, such as BCG and diethylstilbesterol, to activate the reticuloendothelial function, increased susceptibility to endotoxin challenge was observed, and it was suggested that endotoxin tolerance is not
related to the activation of reticuloendothelial function (Suter et al., 1958; Benacerraf et al., 1959; Stuart and Cooper, 1962). Moreover, tolerance to pyrogenicity of endotoxin was observed in the presence of normal phagocytic activity of the reticuloendothelial system, and activation of the
reticuloendothelial system was not necessarily required in the development of endotoxin tolerance (Greisman et al., 1963).
It is well known that liver and spleen consist of major reticuloendothelial tissue but it is not yet clear which organ participates more actively to detoxify endotoxin in the blood stream. It has been also Suggested that distribution of
endotoxin in the body is different between the tolerant and the nontolerant animals. (Smith et al., 1957; Carey et al., 1958 ; Rutenburg et al., 1965; Alper et at., 1967).
In order to provide additional information on endotoxin tolerance, a comparative study was conducted on the hemodynamic changes, antibody formation, endotoxin uptake, and histopathologic alterations in the reticuloendothelial system of
endotoxin tolerant and nontolerant dogs.
Materials and Methods
A. Materials
1. Animals.
a. Dogs: Mongrel dogs, weighing 12 to 18 kg were used.
b. Rabbits: Female albino rabbits, weighing 2.5 to 3.0 kg were used for preparation of rabbit anti-endotoxin anti-serum
2. E. coli strain. E. coli 0111 : B4 NIH (USA), obtained from NIH, Korea and subcultures in trypticase soy agar media (BBL, USA).
3. Endotoxins.
a. Crude endotoxin: prepared by the method of Rubenstein et al. (1962) using aforementioned E. coli strain (Fig. 1).
b. Purified endotoxin: Bacto lipo-polysaccharide E. coli 0111 : B4 (Difco Lab. Detroit, Michigan, U.S.A.).
1. Preparation of rabbit anti-endotoxin anti-serum.
An albino rabbit was inimunized over an 8-month period with 7 courses of intravenous endotoxin injections into a marginal ear vein as follows: day 1, 0.25 ml: day 3, 0.5 ml; day 5, 0.75 ml; day 7, 1.0 ml; day 9, 1.25 ml; day 11, 1.5. On day 14 after the last course, total blood was harvested from a razor-nicked ear
vein. After 2 hours at room temperature, the clot was rimmed and the blood was refrigerated at 4℃ for 18 hours. Serum with free cells was decanted and centrifuged at 2,000 rpm for 30 minutes at 4℃. The cell-free serum was filtered into a sterile rubber stoppered bottle and stored at 4℃.
2. Preparation of tolerant dogs.
Endotoxin tolerant dogs were prepared according to the schedule shown in Table 2 over a 9 to 11 week period.
3. Demonstration of antibody formation in dogs.
By agar gel double diffusion method (Ouchterlony, 1958), precipitating antibody to endotoxin was demonstrated in the serum of endotoxin tolerant animals.
4. Hemodynamic observations.
Experimental animals were divided into 4 groups and the hemodynamic changes were observed.
Grovp Ⅰ -Tolerant dogs with purified endotoxin
Group Ⅱ -Tolerant dogs with crude endotonin
Group Ⅲ -Non-tolerant dogs with purified endotoxin
Group Ⅳ -Non-tolerant dogs with crude endotoxin
Experimental animals were anesthetized with sodium pentothal (30 mg/kg), and the femoral artery was catheterized with a polyethylene tube which was connected to a kymograph to record the blood pressure. At the same time electrocardiographic
findings were recorded. Purified endotoxin, 3 mg/kg, was injected intravenously in Group Ⅰ and Group H animals, and crude endotoxin, 27.6 mg/kg, was injected intravenously in Group Ⅱ and Group 1 animals. Again, blood pressure and electrocardiograph were recorded with observation of animals from 2 to 5 hours.
5. Localization of endotoxin.
Tissues were obtained from the animals after hemodynamic study for localization of endotoxin. The tissue was sectioned by cryostat 3 to 5 μ thick, and stained with fluorescent dye by the method of Rubenstein et al. (1962).
6. Histo-pathologic observation.
With H·E stain, tissues were examined under microscope to determine whether histologic changes, if any, and proliferation and activation of macrophages were present.
Results
A. Detection of antibodies
1. Rabbit anti-endotcxin anti-serum.
Rabbit anti-endotoxin anti·serum was caused to react with purified endotoxin in 0.85 percent agar plate, and a single identical precipitation line was observed in the area of rabbit anti-endotoxin anti-serum. This precipitation line was not
observed when the nonimmunized rabbit strum was used (Fig. 3). After the antibody of rabbit anti-endotoxin anti-serum was reacted with crude endotoxin, the above mentioned precipitation line was not observed (Fig. 4).
2. Endotoxin-tolerant serum of dogs.
Serum obtained from endotoxin tolerant dogs was made to react with endotoxin to verify whether the serum of endotoxin tolerant dogs also produced any antibody to endotoxin and the same precipitation line as seen in the case of rabbit anti-endotoxin antiserum was observed. This precipitation was observed in 48 hours when crude endotoxin was used and in 4 days when purified endotoxin used.
B. Hemodynamic changes
1. Changes of blood pressure.
When endotoxin tolerant dogs were challenged with a shock dose of endotoxin by the intravenous route, blood pressure fell rapidly up to 15-20% of initial pressure. About 5 minutes after endotoxin challenge, blood pressure recovered gradually over a 2 to 5 hour period, the recovery pattern being shown in Fig. 6, 7,
8, 9. Endotoxin tolerant and non-tolerant dogs showed a similar recovery pattern of blood pressure. However, tolerant dogs skewed very little secondary fall of blood pressure(Fig. 6 & 7) and non-tolerant dogs did not recover from the first fall of blood pressure (Fig. 8) or skewed a profound secondary fall of blood pressure and this finding was core remarkable in the dogs when crude endotoxin was used (Fig. 10).
2. Electrocardiographic change.
Tolerant dogs showed no change in pulse rate or ECG tracing, but non-tolerant dogs showed Persistent depression of S-T segments in the ECG tracing, which suggested myocardial ischemia (Fig. 11).
C. Localization of endotoxion
A large amount of specific fluorescent material wart observed in the sinusoid, central vein and interlobular space of liver, splenic sinusoid, and alveolar cell of the lung. Especially, in the liver, cytoplasm of macrophages contained a large amount of fluorescent material, and this was not observed in spleen and lung. There was no difference in amount of fluorescent material between spleen and liver tissue.
D. Histopathologic observation
By H-E stain, macrophages proliferated prominently in the liver of endotoxin tolerant dogs to form granuloma which contained particulated materials which might be hemosiderin, and this finding suggested activation of macrophages. In the liver
of the non-tolerant dogs proliferation of macrophages was not observed nor in the spleen and Lung of the tolerant and the non-tolerant dogs.
Tissue of non·tolerant dogs challenged with a single lethal dose of endotoxin showed no remarkable change by H-E stain.
Conclusion and Summary
1. The agar gel double diffusion method showed the presence of a specific antibody to purified endotoxin by apperance of a single identical precipitation line which is identical with one in rabbit anti-endotoxin anti-serum.
2. Fluorescent antibody technique demonstrated a significant amount of specific fluorescent material in the sinusoid, central vein and interlobular space of the liver, the sinusoid of spleen, and in the alveolar cell of lung in both tolerant and nontolerant dogs. There observed no apparent difference in the amount of
fluorescent material of liver and spleen between the tolerant and nontolerant dogs.
3. Recovery from endotoxin shock in the hemodynamic study was far better in tolerant dogs than in nontolerant ones, and myocardial ischemia was demonstrated by ECG reoording in the nontolerant after endotoxin challenge.
4. Histopathologic examination of liver tissue fron tolerant dogs revealed a feature of macrophage activation, but such a finding was not observed in the liver from nontolerant dogs and in the spleen and lung from the tolerant and nontolerant dogs.