Carbon Phagocytosis Research Articles

Effects of Ganoderma lucidum polysaccharide peptide ameliorating cyclophosphamide-induced immune dysfunctions based on metabolomics analysis.

Ganoderma lucidum polysaccharide peptide (GLPP) is one of the most abundant constituents of Ganoderma lucidum (G. lucidum), with a wide range of functional activities. The present study investigated the immunomodulatory effects of GLPP in cyclophosphamide (CTX)-induced immunosuppressive mice. The results showed that 100 mg/kg/day of GLPP administration significantly alleviated CTX-induced immune damage by improving immune organ indexes, earlap swelling rate, the index of carbon phagocytosis and clearance value, secretion of cytokines (TNF-α, IFN-γ, and IL-2), and immunoglobulin A(IgA) in the mice. Furthermore, ultra-performance liquid chromatography with mass/mass spectrometry (UPLC-MS/MS) was conducted to identify the metabolites, followed by biomarker and pathway analysis. The results showed that GLPP treatment alleviated CTX-induced alterations in the fecal metabolome profile, including arachidonic acid (AA), leukotriene D4 (LTD4), indole-3-ethanol, and formyltetrahydrofolate (CF), by reversing citric acid, malic acid, cortisol, and oleic acid. These results support the concept that GLPP exhibits immunomodulatory activity via the folate cycle, methionine cycle, TCA cycle, fatty acid biosynthesis and metabolism, glycerophospholipid metabolism, AA metabolism, and cAMP pathways. In conclusion, the results could be helpful to understand the use of GLPP to clarify the immunomodulatory mechanism and be used as immunostimulants to prevent CTX-induced side effects in the immune system.

IMMUNOMODULATORY ACTIVITY OF MUNTINGIA CALABURA L. FRUITS USING CARBON CLEARANCE ASSAY AND THEIR TOTAL FLAVONOID AND PHENOLIC CONTENTS

Objective: Muntingia calabura L fruits have several advantages for health and can be consumed as alternative medicine. This study aims to evaluate the immunomodulatory activity of methanol extract (ME) and fractions of M. calabura L fruits against non-specific immune response in mice and its total phenolic and flavonoid contents.
 Methods: This research using carbon clearance assay or phagocytosis method which was done on mice. Seventy male Swiss mice were divided into 14 groups. Mice were treated with ME, hexane fraction (HF), dichloromethane fraction (DF), and ethyl acetate fraction (EAF) of M. calabura L. orally at a dose of 50, 100, and 200 mg/kg daily for 7 days. Zymosan with a dose of 15 mg/kg was used as a positive control and given intraperitoneally, and CMC Na was used as a negative control. On the 8th day, mice were injected with carbon ink suspension intravenously and blood samples were taken at the minutes of 0, 5, 10, 15, 20, and 30. Furthermore, the transmittance was measured at λ 675 nm. The total phenolic content was measured using the Folin–Ciocalteu method, and flavonoid content was measured using the AlCl3 method.
 Results: Zymosan, ME, and EAF of M. calabura L. at a dose of 200 mg/kg showed a strong immunostimulatory effect (phagocytic index >1.5) while the HF and DF groups showed that the higher doses decreased the phagocytic index. The total phenolic contents of ME, HF, DF, and EAF were 27.90, 11.11, 16.72, and 30.11%, respectively, while the flavonoid contents were 4.07, 0.17, 3.07, and 1.86%, respectively.
 Conclusion: ME and EAF of M. calabura L. fruits have immunostimulatory activity.

Thyroid Hormone-Induced Cytosol-to-Nuclear Translocation of Rat Liver Nrf2 Is Dependent on Kupffer Cell Functioning

L-3,3′,5-triiodothyronine (T3) administration upregulates nuclear factor-E2-related factor 2 (Nrf2) in rat liver, which is redox-sensitive transcription factor mediating cytoprotection. In this work, we studied the role of Kupffer cell respiratory burst activity, a process related to reactive oxygen species generation and liver homeostasis, in Nrf2 activation using the macrophage inactivator gadolinium chloride (GdCl3; 10 mg/kg i.v. 72 h before T3 [0.1 mg/kg i.p.]) or NADPH oxidase inhibitor apocynin (1.5 mmol/L added to the drinking water for 7 days before T3), and determinations were performed 2 h after T3. T3 increased nuclear/cytosolic Nrf2 content ratio and levels of heme oxygenase 1 (HO-1), catalytic subunit of glutamate cysteine ligase, and thioredoxin (Western blot) over control values, proteins whose gene transcription is induced by Nrf2. These changes were suppressed by GdCl3 treatment prior to T3, an agent-eliciting Kupffer-cell depletion, inhibition of colloidal carbon phagocytosis, and the associated respiratory burst activity, with enhancement in nuclear inhibitor of Nrf2 kelch-like ECH-associated protein 1 (Keap1)/Nrf2 content ratios suggesting Nrf2 degradation. Under these conditions, T3-induced tumor necrosis factor-α (TNF-α) response was eliminated by previous GdCl3 administration. Similar to GdCl3, apocynin given before T3 significantly reduced liver Nrf2 activation and HO-1 expression, a NADPH oxidase inhibitor eliciting abolishment of colloidal carbon-induced respiratory burst activity without altering carbon phagocytosis. It is concluded that Kupffer cell functioning is essential for upregulation of liver Nrf2-signaling pathway by T3. This contention is supported by suppression of the respiratory burst activity of Kupffer cells and the associated reactive oxygen species production by GdCl3 or apocynin given prior to T3, thus hindering Nrf2 activation.

Hepatocyte Transplantation-Induced Liver Inflammation Is Driven by Cytokines-Chemokines Associated With Neutrophils and Kupffer Cells

Hepatocyte transplantation-induced liver inflammation impairs cell engraftment. We defined whether proinflammatory cytokines and chemokines played roles in regulation of hepatocyte engraftment in the liver. We performed studies over up to 3 weeks in rat hepatocyte transplantation systems. Expression of 84 cytokine-chemokine genes was studied by quantitative real-time polymerase chain reactions. Expression of selected up-regulated genes was verified by immunohistochemistry. Hepatic recruitment of neutrophils was demonstrated by myeloperoxidase activity assays, and Kupffer cell activation was established by carbon phagocytosis assays. The role of neutrophils and Kupffer cells in regulating expression of cytokine-chemokine genes as well as cell engraftment was determined by cell depletion studies. Within 6 hours after syngeneic cell transplantation, expression of 25 cytokine-chemokine genes increased by 2- to 123-fold, P < .05. These genes were largely associated with activated neutrophils and macrophages, including chemokine ligands, CXCL1, CXCL2, CCL3, CCL4; chemokine receptors, CXCR1 or CXCR2, CCR1, CCR2; and regulatory cytokines tumor necrosis factor alpha and interleukin-6. Inflammatory cells in the liver immunostained for CCR1, CCR2, CXCR1, and CXCR2, which indicated that up-regulated messenger RNA was appropriately translated. When neutrophils and Kupffer cells were depleted with neutrophil antiserum and gadolinium chloride, respectively, before transplanting cells, cell transplantation-induced cytokine-chemokine responses were attenuated. Virtually all abnormalities subsided in animals treated with neutrophil antiserum plus gadolinium chloride. Moreover, depletion of neutrophils or Kupffer cells improved engraftment of transplanted cells. Cell transplantation-induced liver inflammation involves proinflammatory cytokine-chemokine systems capable of modulation by neutrophils and Kupffer cells. This offers new directions for optimizing cell therapy strategies.

Thyroid hormone preconditioning: Protection against ischemia-reperfusion liver injury in the rat

Recently, we reported that oxidative stress due to 3,3',5-triiodothyronine (T(3))-induced calorigenesis up-regulates the hepatic expression of mediators promoting cell protection. In this study, T(3) administration in rats (single dose of 0.1 mg/kg intraperitoneally) induced significant depletion of reduced liver glutathione (GSH), with higher protein oxidation, O(2) consumption, and Kupffer cell function (carbon phagocytosis and carbon-induced O(2) uptake). These changes occurred within a period of 36 hours of T(3) treatment in animals showing normal liver histology and lack of alteration in serum AST and ALT levels. Partial hepatic ischemia-reperfusion (IR) (1 h of ischemia via vascular clamping and 20 h reperfusion) led to 11-fold and 42-fold increases in serum AST and ALT levels, respectively, and significant changes in liver histology, with a 36% decrease in liver GSH content and a 133% increase in that of protein carbonyls. T(3) administration in a time window of 48 hours was substantially protective against hepatic IR injury, with a net 60% and 90% reduction in liver GSH depletion and protein oxidation induced by IR, respectively. Liver IR led to decreased DNA binding of nuclear factor-kappaB (NF-kappaB) (54%) and signal transducer and activator of transcription 3 (STAT3) (53%) (electromobility shift assay), with 50% diminution in the protein expression of haptoglobin (Western blot), changes that were normalized by T(3) preconditioning. T(3) administration involving transient oxidative stress in the liver exerts significant protection against IR injury, a novel preconditioning maneuver that is associated with NF-kappaB and STAT3 activation and acute-phase response.

Kupffer cell stimulation in the isolated perfused rat liver triggers nuclear factor-κB DNA binding activity

Activation of transcription factor NF-κB (electrophoretic mobility shift assay) was investigated in the isolated perfused rat liver infused with 0.5 mg of colloidal carbon/ml for 5-20 min, in relation to carbon phagocytosis and carbon-induced O2 consumption. Experiments were carried out in control rats and in animals treated with the Kupffer cell inactivator gadolinium chloride (GdCl3). Carbon uptake and carbon-induced O2 consumption by perfused livers exhibited a linear increase as a function of the perfusion time, leading to constant O2/carbon uptake ratios, with low (0.04-0.15%) fractional sinusoidal lactate dehydrogenase release in the 5-20 min perfusion time studied. NF-κB DNA binding activity showed a maximal enhancement at 10 min of carbon perfusion, a response that was sustained at a lower extent at 15 and 20 min of carbon stimulation. After 10 min of carbon infusion, NF-κB activation, carbon-induced O2 consumption, and carbon uptake were diminished by 84%, 94%, and 64% by GdCl3 treatment (P < 0.05), respectively. It is concluded that the respiratory burst of carbon-stimulated Kupffer cells triggers NF-κB activation in the isolated perfused liver, a response that is elicited under optimal conditions of Kupffer cell function and organ viability.

Influence of C-phycocyanin on hepatocellular parameters related to liver oxidative stress and Kupffer cell functioning.

Kupffer cells, liver macrophages involved in immunomodulation, phagocytosis, and biochemical attack, can induce cytotoxicity and inflammation when their activity is exacerbated. The aim of this study was to evaluate the effects of C-phycocyanin on Kupffer cell functioning considering its antioxidant and anti-inflammatory properties. Actions of C-phycocyanin on colloidal carbon phagocytosis, carbon-induced respiratory burst activity, and sinusoidal lactate dehydrogenase (LDH) release were studied in isolated perfused mouse liver. The influence of C-phycocyanin on tumor necrosis factor-a (TNF-alpha) and nitrite levels in serum and liver nitric oxide synthase (NOS) activity was assessed in rats subjected to thyroid hormone (T3) administration, a condition known to underlie hepatic oxidative stress comprising an increased Kupffer cell activity. C-phycocyanin elicited a concentration-dependent inhibition of carbon phagocytosis and carbon-induced O2 uptake (IC50 = 0.2 mg/ml) by perfused livers, with a 52% diminution in the carbon-induced sinusoidal release of LDH being found at a concentration of 0.25 mg/ml. Thyroid calorigenesis induced an 82-fold increase in serum TNF-alpha levels, an effect that was suppressed by pretreatment with C-phycocyanin, the antioxidant alpha-tocopherol, and by the Kupffer cell inactivator gadolinium chloride. C-phycocyanin also suppressed the T3-induced increases in serum nitrite levels (234%) and in the activity of hepatic NOS (75%). C-phycocyanin significantly decreases Kupffer cell phagocytosis and the associated respiratory burst activity, effects that may contribute to the abolition of oxidative stress-induced TNF-alpha response and NO production by hyperthyroid state.

Influence of aging on Kupffer cell respiratory activity in relation to particle phagocytosis and oxidative stress parameters in mouse liver

The influence of aging on the respiratory activity of stimulated Kupffer cells was investigated in the isolated perfused mouse liver in relation to colloidal carbon phagocytosis, and the content of glutathione (GSH) and protein carbonyls as parameters related to oxidative stress. Livers from aged (22 months) mice exhibited significant 35% and 65% decreases in the carbon uptake and in the carbon-induced O2 consumption compared to young (3 months) animals, respectively, with a concomitant 46% diminution in the carbon-induced O2 consumption/carbon uptake ratio. Hepatic GSH depletion was observed in aged mice compared to young animals, whereas protein oxidation was enhanced. It is concluded that aging leads to an impairment in the functional capacity of Kupffer cells reflected by a substantial reduction in their respiratory burst activity, lessened endocytic capacity and enhanced oxidative stress, that may contribute to increased susceptibility of the liver to noxious challenges.

Influence of copper-(II) on colloidal carbon-induced kupffer cell-dependent oxygen uptake in rat liver: Relation to hepatotoxicity

Formation of reactive O2 species in biological systems can be accomplished by copper-(II) (Cu2+) catalysis, with the consequent cytotoxic response. We have evaluated the influence of Cu2+ on the respiratory activity of Kupffer cells in the perfused liver after colloidal carbon infusion. Studies were carried out in untreated rats and in animals pretreated with the Kupffer cell inactivator gadolinium chloride (GdCl3) or with the metallothionein (MT) inducing agent zinc sulphate, and results were correlated with changes in liver sinusoidal efflux of lactate dehydrogenase (LDH) as an index of hepatotoxicity. In the concentration range of 0.1–1 μM, Cu2+ did not modify carbon phagocytosis by Kupffer cells, whereas the carbon-induced liver O2 uptake showed a sigmoidal-type kinetics with a half-maximal concentration of 0.23 μM. Carbon-induced O2 uptake occurred concomitantly with an increased LDH efflux, effects that were significantly correlated and abolished by GdCl3 pretreatment or by MT induction. It is hypothesized that Cu2+ increases Kupffer cell-dependent O2 utilization by promotion of the free radical processes related to the respiratory burst of activated liver macrophages, which may contribute to the concomitant development of hepatocellular injury.

Effects of the Kupffer cell inactivator gadolinium chloride on rat liver oxygen uptake and content of mitochondrial cytochromes

The effect of gadolinium chloride (GdCl3) on the content of rat liver mitochondrial cytochromes was investigated in relation to the basal rate of O2 uptake and Kupffer cell functioning, assessed in liver perfusion studies. (1) A single dose of GdCl3 (10 mg/kg) produced a significant diminution in Kupffer cell functioning, evidenced by the decreases in colloidal carbon uptake and in carbon-induced O2 uptake observed at 6–24 h after treatment, without changes in the sinusoidal lactate dehydrogenase efflux as index of tissue viability; at 48 h after GdCl3 administration, carbon phagocytosis was recovered to control values, whereas carbon-induced O2 uptake remained lower than control values. (2) GdCl3 also caused a 34% decrease in the basal rate of O2 consumption of the liver at 24 h after treatment, which returned towards control values at 48 h. (3) The content of mitochondrial cytochromes c1 and c at 24 h after GdCl3 treatment was significantly reduced by 40 and 32%, respectively, which returned to control values at 48 h, without changes in that of cytochromes b and a+a3. It is concluded that GdCl3-induced decrease in liver O2 consumption is a reversible phenomenon that seems to be due to a diminution in the content of mitochondrial cytochromes c1 and c.

Dose-dependent effects of acute lindane treatment on Kupffer cell function assessed in the isolated perfused rat liver

1. Twenty-four hours after lindane exposure (5-60 mg/kg) a dose-dependent increase in the serum and hepatic levels of the insecticide was observed. Both the basal rate of O2 consumption and the sinusoidal e ux of lactate dehydrogenase (LDH) by the perfused rat liver was enhanced after the administration of 20-60 mg lindane/kg. 2. The administration of low doses of lindane (5-20 mg/kg) increased carbon uptake and the carbon-induced O2 consumption by the perfused liver, effects that were abolished by pretreatment with the Kupffer cell inactivator gadolinium chloride (GdCl3). These parameters were not modified at the higher doses of lindane used (40-60 mg/kg). 3. In the dose range of 20-60 mg/lindane kg, carbon infusion led to a further increase inliver LDHe uxover values foundinits absence,aneffect that was markedly diminished by GdCl3 in rat treated with 20 mg lindane/kg, being unaltered by GdCl3 in animals given 60 mg/kg. 4. It is concluded that lindane induces a dose-dependent biphasic effect on Kupffer cell function, which could be conditioned by differential membrane perturbation actions of the insecticide that progressively accumulates in the liver, thus altering receptor-mediated and enzymatic processes related to colloidal carbon phagocytosis. Increased Kupffer cell function at low doses of lindane leads to enhanced liver injury. However, this feature of lindane intoxication at higher doses (60 mg/kg) is independent of Kupffer cell activity and seems to be determined by an oxidative stress mechanism induced at the parenchymal cell level.

Influence of colloidal carbon phagocytosis as a metabolic load on the hepatic energy metabolism in rats

The influence of phagocytosis on hepatic energy metabolism was investigated in rats injected with colloidal carbon. Following injection of 6 mg colloidal carbon per 100 g body wt (BW) the hepatic energy charge potential (ECP) remained unchanged. However, oxidative phosphorylation of the isolated mitochondria (PR) increased significantly to 120 and 124% of the control at 1 and 3 hr, respectively, and returned to the normal range at 6 hr. The pyruvate level rose to 195 and 150% at 3 and 6 hr. The lactate level was elevated to 195 and 143% at 3 and 6 hr. Following injection of 20 mg colloidal carbon per 100 g BW, the ECP decreased from 0.865 to 0.783 at 1 hr, but recovered to the normal range thereafter. The PR increased more markedly to 135% at 1 hr, concomitant with an elevation of the ketone body ratio. At 3 hr it remained elevated at 118%, but returned to the normal level at 6 hr. The pyruvate and lactate levels increased to more than 250% at 1 and 3 hr. At 6 hr, the lactate level returned to the control level, but the pyruvate level showed still higher level than the control. These results indicate that phagocytosis exerts an acute metabolic load on the total liver. It was tentatively proposed that parenchymal and nonparenchymal cells in the liver have interrelation in the energy metabolism, and that an enhancement of hepatocellular mitochondrial phosphorylative activity occurs to assist the accelerated metabolism due to phagocytosis.

Ultrastructural and functional development of macrophages in the dermal tissue of rat fetuses.

After about 12 days of gestation, fetal macrophages begin to appear in the subepidermal mesenchyme of rat fetuses. The macrophages are ultrastructurally characterized by cytoplasmic vacuoles, abundant polyribosomes and long filopodia. Immunocytologically, they possess Fc and complement (C3) receptors on the cell surface and are capable of immune phagocytosis, Latex or carbon phagocytosis, and glass adherence. From 15 days of gestation, lysosomal granules and micropinocytic vesicles gradually develop, together with an enlargement of Golgi complexes, whereas the number of polysomes and the number and size of cytoplasmic vacuoles are gradually reduced when gestation ends. Finally, the macrophages become amoeboid. Non-specific esterase and endogenous peroxidase activities are always absent in these macrophages. In culture experiments with cell suspensions prepared from the mesenchyme, fetal macrophages show a similar maturation process. Autoradiography with 3H-thymidine demonstrates a high proliferative capacity of the macrophages, particularly during the fetal stage.

Hepatocyte and Kupffer cell functions during liver regeneration in streptozotocin-diabetic rats.

The insulinoprivic influence of acute severe streptozotocin diabetes on liver regeneration in rats was evaluated by determining liver weights as well as hepatocyte and Kupffer cell functional capacities. Functional capacities were assessed by bromosulfophthalein uptake for hepatocytes and carbon phagocytosis for Kupffer cells. Evaluation immediately after partial hepatectomy revealed a 66% reduction of liver mass, a 63% decrease in hepatocyte bromosulfophthalein removal, and a 65% decline in Kupffer cell carbon phagocytosis. Per cent recovery at 48-hr posthepatectomy was considerably greater for carbon phagocytosis than for bromosulfophthalein removal by regenerating livers. This apparent difference in functional recovery was likely due in part to enhanced non-Kupffer cell carbon phagocytosis. No significant differences of the three regeneration indices were noted for untreated streptozotocin-diabetic rats compared to nondiabetic animals. However, insulin administration to fasted streptozotocin diabetics significantly stimulated liver regeneration above that of untreated fasted rats and almost equivalent to that of pair-fed animals. Fasted rats had in general slower liver regeneration than pair-fed animals as expected. Furthermore, insulin administration to fasted nondiabetic rats after partial hepatectomy caused severe hypoglycemia and resulted in a further depression of liver regeneration.

RES hyperphagocytosis by rats with streptozotocin-induced diabetes mellitus.

In contrast to previous studies of neutrophils from diabetic animals and humans in vitro and of macrophages from diabetic humans in vivo, which reported phagocytic depression, reticuloendothelial system (RES) hyperphagocytosis of colloidal carbon was observed in rats at 14 and 28 days after diabetes induction with streptozotocin (STZ). Carbon clearance half times were significantly enhanced to 6.3 +/- 0.79 and 8.1 +/- 1.04 min at 14 and 28 days post-STZ, respectively, compared with the nondiabetic value (12.7 +/- 0.98 min). The severity of uncontrolled STZ-induced diabetes in rats was confirmed by significant hypoinsulinemia, hyperglucagonemia, hyperglycemia, and hyperlipidemia. Although body weights of STZ-diabetic animals declined progressively, liver weights as a percent of body weight increased above the control value at 14 and 28 days post-STZ. In fact, expression of carbon phagocytosis as the corrected phagocytic index, which accounts for changes in liver and spleen weights relative to body weight, eliminated the significant difference between STZ-diabetic and nondiabetic animals. Antibiotic treatment of diabetic rats failed to alter the hyperphagocytosis, implying that a chronic bacterial infection was not the cause of phagocytic stimulation. Daily insulin replacements, but not a single large insulin dose to 14-day post-STZ rats, reversed the enhanced phagocytosis of colloidal carbon.

Mechanisms of acute hyperinsulinemia after Kupffer cell phagocytosis.

Blockade of hepatic Kupffer cells by prior phagocytosis of a variety of particulate materials caused acute hyperinsulinemia in glucose-stimulated fasted rats under pentobarbital anesthesia. At 4-h postblockade a 125-250% increase in peripheral plasma insulin levels occurred due to a combination of enhanced pancreatic insulin secretion and depressed hepatic insulin extraction. Enhanced pancreatic insulin secretion was confirmed by a 36-54% elevation of portal venous insulin levels. Depressed hepatic insulin extraction was indicated by a 37-47% reduction in insulin uptake by in situ perfused livers as well as alterations in portal-hepatic venous insulin differences and intravenous insulin tolerance tests in vivo. All parameters began to return toward control values at 24 and 48 h postblockade. Return was slow after inert carbon phagocytosis and rapid after degradable bacteria phagocytosis. Peripheral plasma insulin levels were very highly correlated with glucose clearance rates in all groups both control and experimental. Mechanisms are proposed to explain these findings based on the release of lysosomal enzymes and endogenous pyrogens by phagocytizing Kupffer cells as well as the presence of insulin receptors on hepatocytes and Kupffer cells.

Action of mannitol in various immunological experimental models

The authors describe the inhibiting action of mannitol after repeated administration of low subcutaneous doses in a number of experimental immunological models. For example, in the rat it produces a reduction of the secondary arthritis of Freund's adjuvant polyarthritis and also of the pleurisy due to Bordetella pertussis hypersensitivity. In the mouse it reduces the reaction of delayed hypersensitivity to sheep red cells. Its action is also marked against ovalbumin-induced active skin anaphylaxis in the albino guinea-pig and on IgE synthesis in the rat. Moreover, after several injections it produces a reduction of carbon phagocytosis in the mouse. At the doses at which the effect appeared, no action could be found on various models of acute non-immune inflammation, diuresis, blood pressure, hematocrit and protein and plasma sodium levels.

Structural alterations after in vivo administration of phytohaemagglutinin.

THE addition of phytohaemagglutinin (PHA) to tissue cultures in vitro has been shown to produce the transformation of normal lymphocytes into blast cells which undergo mitosis1. Although PHA has been widely investigated in vitro, few reports have appeared about the in vivo effects of this plant mitogen. Thus an increase in the mitotic rate of bone marrow cells has been found in young rats after PHA administration2. Conflicting results have been reported about the effect of PHA in human anaemias3–5, the immune response in laboratory animals6–9 and transplantable tumours10–11. A marked depression of the carbon phagocytosis has been found after a single large dose of PHA12. Small doses of PHA, however, do not alter the rate of disappearance of aggregated human albumin from the circulation9. Despite the considerable interest existing concerning the in vivo action of PHA, no reports of histological changes have appeared, other than the splenic cellular alteration described by Gamble13. This study was therefore undertaken to provide further understanding of the cellular alterations occurring in the spleen as well as in the thymus, lymph nodes and the liver after the in vivo administration of PHA.

Comparative Effects of Endotoxin and Gelatin on Reticuloendothelial Activity.

SummaryColloidal carbon ink (C11/ 1431a) and various commercial gelatin preparations were pyrogenic in rabbits. Cross-tolerance studies indicated the existence of endotoxin in pyrogenic gelatins. Three of seven gelatin preparations depressed carbon phagocytosis in rats when administered 30 minutes prior to the clearance test; however, no significant correlation existed between gelatin pyrogenicity and depression of phagocytosis. All 3 RE interacting gelatins had alkaline isoelectric ranges. Gelatin pretreatment depressed a subsequent carbon clearance while endotoxin induced a marked but delayed increase in carbon phagocytosis. Chronic injections of endotoxin markedly stimulated the RES as reflected in enhanced phagocytosis and splenomegaly; in contrast, chronic gelatin administration produced no such effects. It appears that the influence of gelatin on the RES is not mediated solely by a pyrogenic endotoxin contaminant.

Function of the reticuloendothelial system. II. Participation of a serum factor in carbon clearance.

Reticuloendothelial clearance of carbon particles is inhibited by injection of heat-aggregated albumin. The possibility that this inhibition might involve a serum component has been explored. Evidence that such a serum factor does participate in carbon clearance inhibition by heat-aggregated albumin derives from the fact that prior treatment of the carbon with homologous serum eliminates the blockade; and also, if serum previously absorbed with carbon is mixed with the carbon particles no restoration of "blockade" by albumin occurs. A method for extracting the component from serum using barium sulfate adsorption is described which allows concentration of the factor and sensitive assay for its presence. It is concluded that while large or multiple carbon injections may bring about a saturation of the phagocytic cell, this saturation masks an underlying factor which protects against acute inhibition of carbon phagocytosis by denatured albumin when subsaturating carbon doses are used.