Journal of the Reticuloendothelial Society最新文献

C3H mice develop heavier degrees of Pneumocystis carinii pneumonia than other mouse strains tested. We have compared P. carinii pneumonia in two strains of C3H mice: C3H/HeJ mice, which are unresponsive to the effects of bacterial lipopolysaccharide (LPS), have defects in macrophage function, and have increased antibody responses to orally administered T-dependent antigens; and C3HeB/FeJ mice, which are immunologically normal. P. carinii pneumonia was induced by corticosteroids, and the intensity of the infection was judged by a semiquantitative histopathologic scoring system. Heavier degrees of infection were found in C3H/HeJ mice than in C3HeB/FeJ mice. Serum antibodies to P. carinii, measured by an indirect fluorescent antibody technique, were mainly of the IgG class in both strains of mice and varied inversely with the intensity of P. carinii infection in the lungs. Antibody levels were significantly higher in C3H/HeJ mice than in C3HeB/FeJ mice. These data suggest that C3H/HeJ have increased susceptibility to the effects of steroids of host defenses against P. carinii, and heightened serum antibody responses to the organism.

Inhalation of silica was found to cause significant enhancement of alveolar macrophage antibody-dependent cell-mediated cytotoxicity (ADCC) after 14, 42, and 70 days of exposure, while similar treatment using fly ash resulted in significant suppression of ADCC after 42 days of exposure. Both silica and fly ash inhalation depressed the ability of alveolar macrophages from BCG-primed and BCG-rechallenged animals to mediate tumor cell lysis. Fly ash exposure also significantly suppressed the ability of BCG-activated macrophages to lyse target cells by the ADCC mechanism.

The in vivo uptake of endotoxin by the liver from portal vein blood was assessed during a single passage through the liver. 51Cr labeled and unlabeled endotoxin were infused in different amounts into the femoral vein of three groups of lead-sensitized rats: a nonoperated, a sham-operated, and a surgically created reversed Eck fistula (REF) group. Whereas in the former two the infused endotoxin encounters the lung as the first filter organ, the liver performs this function in the latter experimental model. The mortality rates observed in control and sham-operated, lead-sensitized rats were found to correlate closely and reproducibly to the degree of endotoxemia. This assay was then applied to determine the amount of endotoxin eliminated by the liver by establishing, in the REF rat, the amounts of endotoxin that escaped hepatic clearance. Following infusion of 1 microgram of endotoxin/hr into REF rats, approximately 985 ng is found to be taken up by the liver; following 2 micrograms, 1965 ng is sequestered; following 3 micrograms, 2810 ng; and after 4 micrograms, 3175 ng is retained by the liver. Hence, the capacity of the liver to eliminate endotoxin from portal vein blood during a single passage increases as the portal vein endotoxin level rises; it approaches a maximum, suggesting that endotoxin's interaction with the Kupffer cells conforms to classical saturation kinetics. A Lineweaver-Burk plot prepared from these data indicates that the maximal in vivo capacity of the liver to remove endotoxin from portal vein blood approximates 1.5 micrograms/gm liver/hr. Data obtained with the use of radiolabeled endotoxin corroborate the information obtained with the bioassay technique. Endotoxin eliminated by the Kupffer cells in these quantities is slowly disintegrated; 4 hr after termination of the endotoxin infusion, less than 4% of the radiolabel is found in the urine and none in the bile. These observations indicate that the Kupffer cell's functional capacity to sequester and detoxify endotoxin is extensive and far exceeds the requirements imposed by physiological and most pathological conditions.

Cells of the mononuclear phagocyte system contain a cell surface receptor which mediates the uptake of mannose- and fucose-terminated glycoproteins. We have extended the initial studies to human alveolar and monocyte-derived macrophages in culture using two radiolabelled ligands, the synthetic glycoconjugate mannose-bovine serum albumin and the lysosomal glycosidase, beta-glucuronidase. Uptake (37 degrees C) of 125I-mannose-BSA by freshly isolated alveolar macrophages is saturable with increasing concentrations of ligand. Kuptake values in macrophages of smokers and nonsmokers are similar, and resemble earlier reported values using rabbit alveolar macrophages (Kuptake = 40 nM). Uptake of 125I-mannose-BSA in cultured smoker macrophages is identical to that found in fresh cells, and uptake is stable for 5-10 days in culture. Fucose- and mannose-BSA are the most effective inhibitors of uptake, while N-acetylglucosamine-BSA is inhibitory at slightly higher concentrations. Binding (4 degrees C) of 125I-mannose-BSA is likewise ligand concentration dependent (KD = 30 nM). Freshly isolated human monocytes from healthy subjects and patients with cystic fibrosis do not have mannose-specific uptake. However, after monocytes are in culture for 3 days, mannose-specific uptake appears and Kuptake values and specificity of uptake are identical with the results from the alveolar macrophages. No uptake of mannose-BSA could be found in the human monocyte-like cell line, U937.

A mechanism of macrophage activation by a streptococcal preparation (OK-432) was studied. Peritoneal exudate macrophages from normal guinea pigs treated in vitro with OK-432 were activated, manifesting increased glucose consumption, increased spreading, and morphological alterations under scanning electron microscopy. Macrophages showed extensive spreading within 1 hr after OK-432 treatment; they then became rounded with characteristic ruffles in their surfaces after 6 hr of treatment. Highly purified macrophages were activated as effectively as a crude macrophage preparation, suggesting that the macrophage activation resulted from a direct interaction between macrophages and OK-432. However, when spleen cells were treated with OK-432, a factor(s) capable of activating macrophages was produced in the culture supernatant. Spleen macrophage-rich preparation was found to release the factor(s) upon stimulation with OK-432, but this did not occur with the lymphocyte-or granulocyte-rich preparations. These results indicate that OK-432 not only activates macrophages by direct interaction without lymphokine participation, but also augments the activation by affecting spleen cells, probably macrophages, in such a way as to produce monokines.

Human monocytes were separated from peripheral blood of 22 normal healthy adults and incubated with Hsw1N1 influenza virus or diluted allantoic fluid. The treated monocyte populations were tested for five parameters of monocyte function. Influenza infection markedly inhibited the monocyte chemotactic response and the killing of Candida albicans; infection also depressed phagocytosis, slightly reduced spreading, but did not affect adhesion to glass. These results suggest that influenza virus may also have an inhibitory effect on monocyte function in vivo and help to explain the increased susceptibility to secondary bacterial infection and the general immunosuppression seen in influenza infection.

Conventional methods of assessing antibacterial activities of macrophages by viable counting are limited by the precision of the statistics and are difficult to interpret quantitatively because of unrestrained extracellular growth of bacteria. An alternative technique based on the release of radioactive DNA from labeled bacteria has been offered as overcoming these drawbacks. To assess it for use with macrophages I have made a correlation with the conventional viable counting method using a mathematical model. Opsonized Listeria monocytogenes labeled with 3H-thymidine were exposed to rat macrophages for periods up to 4 hr. Numbers of viable bacteria determined after sonication increased exponentially in the absence of live cells and this growth rate was progressively inhibited by increasing numbers of macrophages. After a lag period of 30-60 min soluble 3H appeared in the supernatant, the amount increasing with time and numbers of macrophages. To correlate these data I developed a mathematical model that considered that changes in numbers of viable organisms were due to the difference between rates of 1) growth of extracellular bacteria and 2) killing within the macrophage. On the basis of this model curves of best fit to the viable counts data were used to predict the release of radioactivity, assuming that death of a bacterium led to the total release of its label. These predictions and the experimental data agreed well, the lag period of 30-60 min between death of the bacterium and release of radioactivity being consistent with intracellular digestion. Release of soluble radioactivity appears to be an accurate reflection of the number of bacteria killed within the macrophage.

Experiments were conducted to determine the influence of the pancreatic hormones insulin, glucagon, and somatostatin on reticuloendothelial system (RES) phagocytosis both in vivo and in the isolated perfused livers of rats. Chronic pancreatic hormonal treatment consisted of twice daily injections SC of NPH insulin with doses ranging from 0.75 U on day 1 to 9.0 U on day 13 and unchanged doses of glucagon (200 micrograms) and somatostatin (50 micrograms). Chronic treatment with insulin significantly depressed by 48% intravascular phagocytosis of colloidal carbon administered IV at a dose of 8 mg/100 g, while glucagon and somatostatin stimulated macrophage endocytic function by 32% and 26%, respectively, compared to the control value. Acute treatment with the three pancreatic hormones at 30 min prior to carbon administration similarly produced insulin depression as well as glucagon and somatostatin stimulation of RES phagocytosis. Addition of the three hormones at near physiologic concentrations (20 ng/ml for insulin, 10 ng/ml for glucagon, and 5 ng/ml for somatostatin) to the recirculating perfusate of isolated perfused rat livers simultaneous with 24 mg of colloidal carbon likewise resulted in phagocytic reduction after insulin and enhancement after glucagon and somatostatin. Experiments involving insulin in vitro with isolated perfused livers as well as glucose replacement therapy concomitant with insulin in vivo demonstrated that hypoglycemia is not necessary for phagocytic depression by insulin while severe hypoglycemia in the perfusion medium is sufficient to depress carbon uptake by isolated perfused livers independent of insulin. Both pancreatic hormones and the level of glycemia seem to be important in modulating hepatic reticuloendothelial system phagocytosis.

Glucan, a beta-1-3-polyglucosidic component of the cell wall of Saccharomyces cervisiae, was evaluated for its ability to influence the survival rate in rats with induced intraabdominal sepsis. To mimic closely the human bacteriological intestinal flora, the rats, in 4 groups each of 15 animals, were fed a lean meat diet. Intraabdominal sepsis was induced by resecting 1 cm of the intestine and reimplanting it in the abdominal cavity, reestablishing intestinal continuity by one-layer end-to-end anastomosis. The rats were injected with glucan, isovolumetric saline, and ampicillin or glucan plus ampicillin. The results indicate a significant decrease in mortality in the group treated with ampicillin compared with the group treated with saline only. The group treated with glucan plus ampicillin differed significantly from the group given ampicillin. The bacterial flora was not qualitatively influenced by glucan administration. It is concluded that glucan, in combination with ampicillin, has a significant effect on the survival rate of rats with induced peritonitis, probably by enhancing the activities of the reticuloendothelial system--an important part of the total host resistance.

The macrophage content of spontaneously occurring metastases was examined to determine whether metastases represent selected tumor populations that are not infiltrated by macrophages to the same extent as their parent tumors. In this study, we used three different spontaneously metastatic mouse tumors, the B16 melanoma in C57BL/6 mice, and the UV-2237 and UV-1422 fibrosarcomas in C3H/HeN (MTV-) mice. All lung and lymph node metastases in these three tumor systems contained macrophages. Some metastases had fewer, and others had the same or even more infiltrating macrophages than their respective parent tumors. Therefore, in the tumor systems we studied, the survival and growth of metastases are unlikely to be contingent upon the absence of infiltrating macrophages.