Lysosomal enzymes in hepatic injury induced by bromobenzene.

In studies with bromobenzene we found increases in the activities of hepatic lysosomal enzymes. The present study was undertaken to determine how these changes are related to the development of hepatic injury after bromobenzene administration. A single intraperitoneal injection of bromobenzene (5 mmoles/kg) caused significant increases in the total activity of lysosomal N-acetyl-beta-glucosaminidase and beta-glucuronidase in rat liver within 8-12 h, whereas it did not alter the free activity of these enzymes. Enhancement of bromobenzene hepatotoxicity by the pretreatment of rats with phenobarbital was not associated with further changes in hepatic N-acetyl-beta-glucosaminidase or beta-glucuronidase activities. Cycloheximide administered prior to bromobenzene inhibited significantly the effect of bromobenzene on the total N-acetyl-beta-glucosaminidase activity. The results suggest that lysosomal enzymes are not directly involved in hepatic damage caused by bromobenzene and that the inhibition of protein synthesis may reduce this response to hepatotoxin.     

Mild to severe lithium-induced nephropathy models and urine N-acetyl-beta-D-glucosaminidase in rats

Long-term treatment with lithium induces functional and/or structural disturbances in the kidneys. However, no procedure has been established for the early diagnosis of lithium intoxication. In this study, we prepared mild to severe lithium-induced nephropathy rat models and examined the usefulness of urine N-acetyl-beta-D-glucosaminidase (NAG) for the early diagnosis of lithium-induced renal insufficiency. Lithium was administered by repeated intraperitoneal injection (1, 2 and 4 mEq/kg/day for 10 days). We also measured the plasma creatinine and paraaminohippuric acid (PAH) clearance, and observed renal histological changes. Lithium pretreatment elevated the plasma creatinine level and decreased PAH clearance in a dose-dependent manner. The NAG level in the lithium 4 mEq/kg group was very high. The levels in the lithium 1 mEq/kg and 2 mEq/kg groups were almost the same and were higher than the control group. A histological examination of the kidney revealed glomerular congestion and/or atrophy and tubular expansion in all of the groups except the control group. These histological changes were dose-dependent. In conclusion, urine NAG may be useful in the early diagnosis of renal side effects caused by lithium therapy. When the urine NAG level becomes high in a patient taking lithium for bipolar disorder, the physician may need to consider lithium-induced renal insufficiency.     

Distribution of gentamicin among subcellular fractions from rat renal cortex

A substantial amount of data is available to suggest that lysosomal sequestration of aminoglycoside antibiotics plays a role in the pathogenesis of aminoglycoside-induced renal tubule cell injury; however, relatively little information is available on the subcellular distribution of aminoglycosides in the kidney during treatment protocols of the type that ultimately go on to produce extensive lethal renal tubule cell injury and acute renal failure in experimental animals. This study assessed the distribution of gentamicin and subcellular membranes on a discontinuous sucrose density gradient after in vivo exposure of rats to four daily 100 mg/kg doses of gentamicin as compared to in vitro exposure of normal rat renal cortex to gentamicin during tissue homogenization at drug levels comparable to those seen after in vivo treatment. After both in vivo and in vitro exposure, major localization of gentamicin, the lysosomal marker enzyme N-acetyl-beta-D-glucosaminidase (NAG), and the endoplasmic reticulum marker enzyme NADPH-cytochrome c reductase, occurred in a very light membrane fraction. Within this membrane fraction, gentamicin was more closely associated with the NAG than with the NADPH-cytochrome c reductase. The results could not be explained by complete lysosomal disruption during subcellular fractionation after in vivo gentamicin. These data provide additional insights into both the possibilities for subcellular interactions of aminoglycosides in the kidney, and into the methodology required to optimally assess such interactions.     

Enzymatic changes in rat liver associated with low and high doses of a peroxisome proliferator

The activities of a number of lipid-metabolizing and subcellular marker enzymes were measured in total homogenates and subcellular fractions prepared from the livers of male rats fed diets containing 0.05, 0.1, 0.3, and 0.5% of the hypolipidemic drug tiadenol, resulting in mean drug intake of 45, 90, 330, and 530 mg/day/kg body wt, respectively. In the total homogenates, a massive induction of palmitoyl-CoA hydrolase and peroxisomal palmitoyl-CoA oxidation accompanied by increased free CoASH and long-chain acyl-CoA content was observed at the highest dose levels whereas little change occurred up to 90 mg/day/kg/body wt. The palmitoyl-CoA synthetase activity increased slightly up to 90 mg/day/kg body wt, but higher doses resulted in decreased enzyme activity. Catalase activity increased with the dose to be elevated by a factor of approximately 1.6 at 330 mg/day/kg, whereas the activities of urate oxidase decreased. The specific activities of palmitoyl-CoA hydrolase and peroxisomal palmitoyl-CoA oxidation increased in all fractions, but most markedly in the cytosol. The changes in the activities and the distribution of subcellular marker enzymes and the increase of the peroxisome-associated polypeptide (PPA-80) are in keeping with a peroxisome proliferating effect resulting in formation of premature organelles with altered properties. Since high doses of many hypolipidemic drugs produce hepatic tumors and peroxisomal proliferation in rodents and since no increase in peroxisomes is found in human liver after therapeutic use of lower doses, the dose-response relationship is of interest for the evaluation of the toxicology of this class of agents.     

Effects of methylmercuric chloride intoxication on the intracellular activity of lysosomal enzymes in rat liver and brain

The activity of the lysosomal enzymes of rat liver after a single intraperitoneal injection of methylmercuric chloride (5.0 mg/kg) was enhanced in the nuclear fraction during early post-injection (2 hr to 7 days), while it decreased in the mitochondrial fraction and increased in the lysosomal fraction during late post-injection (14 days). Rat brain activity, however, was reduced in the nuclear, mitochondrial and lysosomal fractions during late post-injection (14 days). A high accumulation of total mercury was observed in the liver during early post-injection (36 hr and 7 days) while similar accumulation in the brain occured during late post-injection (7 days and 14 days). Both the mercury burdens and the enzyme activities of the rat liver and brain returned to normal levels within 30 days.     

Effect of NCO-700, an inhibitor of protease, on lysosomal rupture in the ischemic myocardium

The effect of NCO-700 (1), a protease inhibitor, on subcellular distribution of lysosomal enzymes was studied in the ischemic perfused rat heart. Ischemia was induced by lowering the afterload pressure of the working heart preparation. The subcellular distribution of lysosomal enzymes was estimated by the ratio of the activities of cathepsin D, beta,N-acetylglucosaminidase, and acid phosphatase in the cytoplasm to the total enzyme activities. Ischemia caused subcellular redistribution of lysosomal enzymes from the lysosomes to the cytoplasm, indicating the rupture of lysosomes. Compound 1 (1.75 x 10(-4) M) was provided for the heart 5 min before the onset of ischemia. Compound 1 appeared to inhibit the rupture of lysosomes being caused by ischemia. The mechanism by which 1 protects the myocardium against ischemic injury may involve the inhibition of lysosomal rupture in the ischemic myocardium.     

Effect of N-N'-diphenyl-p-phenylenediamine pretreatment on urinary enzyme excretion in cisplatin nephrotoxicity in rats

Two days after cisplatin was injected into rats, urinary N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyltranspeptidase (gamma-GTP) activities increased. The urinary excretion of NAG continued to rise until 4 days after the injection of cisplatin, the last day examined. However, the increase in urinary gamma-GTP excretion which lasted for 2 days returned to its control level 4 days after cisplatin injection. The alkaline phosphatase activity in urine was unaffected by cisplatin injections. The antioxidant N-N'-diphenyl-p-phenylenediamine attenuated these increases in enzyme activities caused by cisplatin. The results of this study suggest that monitoring the change in urinary activities of some enzymes is the method of choice for detecting cisplatin nephrotoxicity and that the increase may involve the generation of free radicals by cisplatin.     

Effect of gentamicin on the subcellular distribution of renal β-N-acetylglucosaminidase activity

The effect of gentamicin on lysosomal enzyme activity in renal cortex of Sprague-Dawley rats was examined. In rats given 60 mg gentamicin/kg subcutaneously for 8 days, renal β-N-acetylglucosaminidase activity increased by 57 per cent while cathepsin B₁ and dipeptidylpeptidase I activities did not change. The specific activity of glucosaminidase in partially purified lysosomes, however, was only 10 per cent higher. The subcellular distribution of glucosaminidase activity in gentamicin-treated rats shifted towards the less dense mitochondrial and 10,000 g supernatant fractions, which showed a 55 and 80 per cent increase, respectively, of total activity. It is concluded that gentamicin caused an increased activity, and reduced latency, of lysosomal glucosaminidase.     

Studies on the nephrotoxicity of aminoglycoside antibiotics and protection from these effects (4). Effects of tobramycin alone and in combination with latamoxef on the stability of rat kidney lysosomal membranes

Effects of tobramycin (TOB) alone and in combination with latamoxef (LMOX) on the stability of rat kidney lysosomal membranes were investigated. Rats were injected with doses of TOB (90 mg/kg/day, s.c.) alone. LMOX (2,000 mg/kg/day, s.c.) alone or TOB (90 mg/kg/day, s.c.) and LMOX (2,000 mg/kg/day, s.c.) for 5 consecutive days. The rat kidney lysosomes were isolated on the 1st, 3rd and 5th days and incubated in a 0.25 M sucrose solution containing 1 mM EDTA (pH 7.0) at 37 degrees C for 20 min. After incubation, the activity of N-acetyl-beta-D-glucosaminidase (NAG) released from lysosomes was measured, and the percent NAG release was calculated as an index of the stability of lysosomal membranes. The percent releases of NAG from lysosomes of TOB alone-treated rats were 40 and 50% greater than those of normal rats on the 1st and 3rd days, respectively. On the other hand, treatment with TOB and LMOX suppressed the NAG release from lysosomes with TOB alone by about 80 to 100%. There were insignificant slight increases in the percent NAG release in LMOX alone-treated rats on the 3rd and 5th days. In addition, the in vitro study indicated that incubation of the lysosomal fraction from kidneys of normal rats with TOB (30 micrograms/ml) significantly increased the NAG release, compared with that of the non-treated lysosomal fraction. However, the preincubated mixture of TOB (30 micrograms/ml) and LMOX (50 micrograms/ml) in vitro significantly suppressed the release of NAG from lysosomes by 85%. These results suggest that the suppression of the releases of NAG from lysosomes by the combination of TOB with LMOX may contribute to the protective effect of LMOX against TOB nephrotoxicity.     

Effects of insulin on maltase and N-acetyl-beta-D-glucosaminidase (NAG) activities of serum and kidney in experimental diabetic rats

The activities of lysosomal maltase in the serum, urine and kidney were determined in rats with diabetes induced by streptozotocin (STZ, 75 mg/kg, i.p.) and compared with the changes in N-acetyl-beta-D-glucosaminidase (NAG) activity. Moreover, effects of insulin on maltase and NAG activities of the serum, urine and kidney in diabetic rats were studied. The following results were obtained: 1) The serum maltase activity within 24 hr after administration of STZ was influenced by insulin secretion. 2) Significant increases in blood urea nitrogen (BUN) levels were observed from the 3rd week after a single administration of STZ. The serum insulin level significantly decreased at 3 weeks after treatment of STZ. In this time, maltase activity in the serum rapidly increased, while the enzyme activity in the kidney decreased considerably. On the other hand, the changes in NAG activities in the serum, urine and kidney after administering STZ were almost similar to those in maltase activities. 3) There were positive relationships between maltase and NAG activities in the serum and urine in diabetic rats, respectively. 4) When lente insulin (2U) was subcutaneously injected once daily for 20 days from 24 hr after administration of STZ, NAG activities in the serum and kidney approached to the control levels. However, maltase activities in the group treated with insulin were significantly higher in the serum and kidney than those in the control group.     

Action of beta-adrenomimetics on the degree of lysosomal membrane damage and glycogen phosphorylase activity of the ventricular myocardium of guinea pigs

The effects of partusisten, novodrin and nonachlazine on the acid phosphatase and glycogenphosphorylase activities in the guinea pig ventricle myocardium were studied. The injection of partusisten (1 mg/kg) significantly increased the acid phosphatase activity and preserved the strong negative correlation between the free activity of acid phosphatase seen in control animals and the "free activity/total activity" ratio. Beta adrenergic agonists exerted different effects on the "glycogenphosphorylase B activity/glycogenphosphorylase A + B activity" ratio.     

Mechanism of lithium action: in vivo and in vitro effects of alkali metals on brain superoxide dismutase

Intraperitoneal administration of lithium (2 mEq/kg/day) was found to increase the superoxide dismutase (SOD) activity in certain brain regions after 24 hours (2 injections) and 3 days (once a day) of exposure. In vitro addition of wide range of lithium (0.1 to 8 mEq) to enzyme preparation as well activated cortical SOD activity; however, at 10 mEq concentrations an inhibition was observed. The increase in SOD activity did not appear to be region specific as under both in vivo and in vitro conditions lithium enhanced enzyme activity in all the tested brain regions. The effects of intraperitoneal administration of 2 mEq/kg rubidium and cesium for 24 hr (2 injections) and 6 days (once a day) were also studied on central SOD. Both the alkali metals were not found to produce any significant alteration in the cortical enzymic activity. When the in vitro effects of these monovalent alkali metals were tested, only 2 mEq rubidium was found to increase cortical SOD; however, cesium and potassium at similar concentration did not produce any appreciable effects. It appears from the data that lithium-induced increase in brain SOD activity is not an unspecific effect of alkali metals. SOD enzyme disposes cytotoxic superoxide radicals which, if not removed, could impair the normal functioning of cellular membrane and produce a variety of psychedelic compounds as well. The activation of central SOD by lithium would enhance the disposal process of superoxide radicals whose pathological concentrations may be present in affective disorders. The mechanism of lithium-induced activation of SOD, at present, is not known.     

Inhibition by lithium and rubidium of gentamicin-induced release of N-acetyl-β-D-glucosaminidase from perfused rat kidney

N-acetyl-β-D-glucosaminidase (NAG) is one of the sensitive hydrolytic lysosomal enzymes which is released after renal tubular damages. We studied gentamicin-induced nephrotoxicity by determining the NAG release in perfused rat kidney. 100 μg/ml of gentamicin caused a time-dependent increase in enzymuria, peaking at 90 min. At this time the released NAG is about sixfold more than the control. The effect of concurrent perfusion with 100 μg/ml gentamicin and with 0.5 mmol/l lithium chloride or 0.5 mmol/l rubidium chloride in the perfusion fluid was also studied by measuring NAG activity in the perfusate. Both cations decrease the gentamicin-induced NAG release. However, the inhibitory effect of lithium chloride may be due to interference of this ion with the polyphosphoinositide cycle in renal tubular lysosomal membranes. There is no obvious evidence for an inhibitory effect of rubidium chloride.     

Induction of peroxisomal enzymes and palmitoyl-CoA hydrolase in rats treated with cholestyramine and nicotinic acid

Male Wistar rats were given 200 mg/kg/day nicotinic acid or 1000 mg/kg/day cholestyramine by stomach tube for ten days. Peroxisomal palmitoyl-CoA oxidation (cyanide-insensitive) and the activities of palmitoyl-CoA hydrolase and urate oxidase were significantly increased in the total liver homogenate. Subcellular fractionation showed enhanced enzyme activities after drug treatment mainly in the peroxisome-containing fractions. The increase in urate oxidase activity and its subcellular distribution suggest that the tested drugs induce core-containing peroxisomes. The findings are similar to those previously reported with low doses of peroxisome-proliferating hypolipidemic drugs and with acetylsalicylic acid, a drug which is structurally similar to nicotinic acid. Since cholestyramine is not absorbed, its influence on hepatic enzymes probably occurs indirectly as a consequence of enhanced catabolism of cholesterol.     

Gentamicin-induced renal metabolic alterations in newborn rat kidney: lack of potentiation by vancomycin

Daily subcutaneous administration of 20 or 100 mg/kg gentamicin for 4 days significantly decreased pyridoxal-5'-phosphate and lysosomal specific phosphatidylinositol-phospholipase C (PI-PLC) in newborn rat kidney. The fall in PI-PLC was associated with an elevation in renal phosphatidylinositol, phosphatidylserine, and phosphatidylcholine. The 100 mg/kg gentamicin dose also produced a rise in renal sphingomyelin, phosphatidylethanolamine, phosphatidylglycerol, and total phospholipid (TPL) accompanied by inhibition in the activities of Na+,K+-ATPase and alkaline phosphatase. In contrast, daily intraperitoneal injection of 100 mg/kg vancomycin for 4 days failed to markedly alter renal metabolic parameters. However, the 500 mg/kg vancomycin dose increased kidney weight, TPL, and all individual phospholipid class concentrations accompanied by inhibition of lysosomal specific PI-PLC activity and reduced pyridoxal-5'-phosphate levels. Simultaneous administration of 20 mg/kg gentamicin with either vancomycin dose resulted in renal alterations similar to those produced by gentamicin alone. Concurrent treatment with 100 mg/kg aminoglycoside and either vancomycin dose produced changes in kidney which were similar to those produced by gentamicin alone, except for a synergistic rise in PI as well as a greater fall in alkaline phosphatase and pyridoxal-5'-phosphate. Surprisingly, the concentration of gentamicin and vancomycin was less in newborn kidneys of rats receiving a simultaneous high dose of vancomycin and aminoglycoside treatment compared to levels found in animals given either antibiotic separately. The lack of potentiation of nephrotoxicity in newborns administered a combination of vancomycin and gentamicin may be due to decreased accumulation of either antibiotic in kidney.     

Effects of lithium on the pharmacokinetics of valproate in rats

Combined treatment with lithium and valproate has been used for bipolar disorder. However, the studied interaction between these two drugs has not been fully investigated. We therefore examined the effects of lithium on the pharmacokinetics (plasma disappearance, metabolism and urinary excretion) of valproate in rats. Lithium (2 mEq kg(-1)) was administered intraperitoneally twice a day for ten days. Plasma disappearance curves of valproate (50 mg kg(-1), i.v.), valproate-metabolizing activities of UDP-glucuronosyltransferase (UGT) and cytochrome P450 (CYP) in liver microsomes and urinary excretion of free valproate and valproate-glucuronide were examined. The metabolizing activity of UGT and CYP were determined by enzyme assays and a fluorescence polarization immunoassay system. Urinary valproate-glucuronide was obtained using this system by subtracting the free level from total level, which was determined after deconjugating the sample with heat and NaOH. The half-life of plasma disappearance of valproate was 25% reduced by lithium pretreatment (0.428 +/- 0.031 h with repeated lithium pretreatment vs 0.578 +/- 0.062 h for controls). The valproate-metabolizing activity of UGT and CYP were not altered by lithium although lithium increased the urinary excretion of valproate-glucuronide. In conclusion, lithium pretreatment causes a decrease in plasma valproate levels and an increase in urinary excretion of valproate-glucuronide in rats.     

Calcium ethylenediaminetetraacetate (CaEDTA) toxicity—Interaction of CaEDTA,cortisol and vitamin a palmitate on lysosomes in vivo in the rat

Lysosomal stabilizers and labilizers attenuate and accentuate, respectively, the effect of CaEDTA in enhancing the degradation of collagen, as evidenced by urinary hydroxyproline excretion. The present study is concerned with evaluating directly the ability of CaEDTA to alter the integrity of rat liver and kidney lysosomes in vivo. The integrity of lysosomes was assessed by measuring the degree of redistribution of lysosomal marker enzymes from the sedimentable or bound fraction to the unsedimentable or soluble fraction and by measuring the activity of lysosomal enzymes in blood plasma. CaEDTA, compared to controls, enhanced the redistribution of cathepsin D and acid phosphatase to the soluble fraction. Total cathepsin D activity in the kidney was increased whereas total acid phosphatase activity in the liver and kidney was decreased. Cortisol (50 mg/kg/8 hr, i.m.) reduced the effect of CaEDTA on redistribution of lysosomal enzymes and abolished the effect of CaEDTA on total renal cathepsin D activity. Vitamin A palmitate (250.000 I.U./kg/12 hr, s.c.) itself produced effects similar to CaEDTA on renal lysosomes; when given concurrently with CaEDTA the increase in total renal cathepsin D activity was additive. The activity of lysosomal enzymes in blood plasma reflected changes in tissues, indicating clearly that release of lysosomal enzymes occurred in vivo. Thus, direct measurement of lysosomal enzyme activity, especially cathepsin D, revealed a close correlation between enzyme activity and the degradation of collagen associated with the administration of CaEDTA, cortisol and vitamin A palmitate. A marked reduction in the concentration of plasma proteins occurred in rats treated with CaEDTA and vitamin A palmitate. A rational basis for the use of cortisol in CaEDTA toxicity is provided by the fact that this drug abolished CaEDTA-induced depletion of plasma proteins.     

Cationic amphiphilic drug-induced renal cortical lysosomal phospholipidosis: an in vivo comparative study with gentamicin and chlorphentermine

Daily subcutaneous injection of gentamicin (100 mg/kg) for 2 days produced a significant decrease in the activities of alkaline phosphatase, a brush-border membrane marker, and Na+-K+ ATPase, a basolateral membrane marker, in adult rat kidney cortex. Analysis of homogenate and lysosomal fractions revealed a significant rise in the concentration of total renal cortical phospholipid, phosphatidylserine, phosphatidylcholine, and phosphatidylinositol. In the lysosomal fraction, an increase in the levels of phosphatidylglycerol and phosphatidylethanolamine was also noted. Daily, oral chlorphentermine (60 mg/kg) administration for 5 days significantly reduced renal Na+-K+ ATPase without a marked change in alkaline phosphatase. As in the case of gentamicin, chlorphentermine produced a significant elevation in phosphatidylserine, phosphatidylcholine, and phosphatidylinositol as well as total phospholipid in both the homogenate and lysosomal fractions of kidney cortex. The observed chlorphentermine- or gentamicin-induced renal phospholipidosis was associated with a significant reduction in the activity of phosphatidylinositol-specific phospholipase C. The drug-induced inhibition of phospholipase C was quantitatively equal in the renal cortical homogenate and lysosomal fractions. In addition, gentamicin significantly inhibited the activity of phosphatidylserine-phospholipase C and phosphatidylcholine-phospholipase C in renal cortical homogenate. In contrast, only the activity of phosphatidylinositol-specific phospholipase C was decreased in chlorphentermine-treated kidneys. Evidence thus indicates that the gentamicin-induced accumulation of phospholipid in renal cortical lysosomes is associated with inhibition of various forms of phospholipase C, while in the case of chlorphentermine the inhibition of different phospholipases may be involved in phospholipid accumulation.     

Effect of in vivo administration of gold sodium thiomalate on rat macrophage function

It has been shown that gold accumulates in macrophages. In vitro studies have also shown that long-term anti-inflammatory and immuno-regulatory effects on these cells may be responsible for the effectiveness of gold in the treatment of rheumatoid arthritis. However, the relevance of this information to the in vivo circumstance is largely untested. In this study, the effect of gold sodium thiomalate (AuTM) on rat alveolar macrophage (AM) lysosomal enzymes, bacterial killing, and metabolic activities associated with phagocytosis were assessed after in vivo administration. The activities of beta-glucuronidase, acid phosphatase, and lysozyme were inhibited 1 day following a single AuTM injection (50 mg/kg, subcutaneous). However, lysozyme returned to normal, while the activities of beta-glucuronidase and acid phosphatase were elevated from 4 to 12 days thereafter. When AuTM was administered weekly for 8 weeks, the activities of acid phosphatase and beta-glucuronidase were elevated throughout, while lysozyme was largely unaffected. The increased lysosomal enzyme activities were not due to contamination of polymorphonuclear leukocytes. These long-term effects of AuTm on enzyme activity were in marked contrast to its in vitro effect which inhibited the activities of beta-glucuronidase and acid phosphatase. No effect of AuTM administration on the release of beta-glucuronidase upon phagocytosis of opsonized zymosan was observed. At 1 day following a single AuTM injection or 3 days after a second weekly injection, in vivo bactericidal activity of AM toward S. aureus was diminished. This bacterial killing defect was not due to decrease phagocytosis; the in vivo binding and ingestion of bacteria were normal. The defect correlated with imparied metabolic activities associated with phagocytosis, namely a significant decrease in the reduction of nitroblue tetrazolium and the stimulation of the hexose monophosphate shunt. This may be an attractive anti-inflammatory effect in light of the destructive potential of the reactive oxygen species produced by macrophages in an arthritic circumstance.     

Cyclosporin A enhances the pulmonary granuloma response induced by Schistosoma mansoni eggs

The modulating effect of cyclosporin A (CsA) was studied in the immune-based pulmonary granuloma response to Schistosoma mansoni eggs. The extent of the S. mansoni egg-induced inflammation was quantitated biochemically by measuring total units of N-acetyl-beta-D-glucosaminidase (NAG) and total lung DNA. The enzyme NAG was used as a marker for the activity of inflammatory cells such as macrophages and DNA levels were used to quantify the increased cellularity of the lungs. In this model, the inflammatory response is maximal approximately 2 weeks after egg injection. Daily oral administration of CsA at 50 mg/kg during the first 2 weeks of the response dramatically enhanced the levels of pulmonary inflammation. Similar augmentation of the granuloma response was seen when CsA was given from days 0 to 7 but not when dosed from days 8 to 14. The enhancing of CsA was seen in the high-responder strains C57BL/10, B10.BR and CBA and in a lower-responder strain, Balb/c. Both the S. mansoni egg-induced granuloma response and the CsA-induced enhancement were dependent on functional T cells: athymic C57BL/6 nude (nu/nu) mice developed minimal responses to S. mansoni eggs which CsA did not augment, while heterozygous (nu/+) euthymic B6 mice responded to S. mansoni eggs and CsA. It appears in this model system that CsA may inhibit the activity of suppressor inducer or suppressor T cells. Cyclophosphamide, a drug known to reduce suppressor cell function, augmented the egg-induced inflammatory response similar to CsA. The enhancing activities of CsA and cyclophosphamide were not additive, suggesting effects on a common pathway of biologic activity, the generation of suppressor cells. While CsA and cyclophosphamide augmented the inflammatory process, conventional immunosuppressive drug therapies, dexamethasone and BW755c, quantifiably reduced the levels of NAG and DNA. These results demonstrate that CsA, rather than being immunosuppressive, augments this immune-based model of inflammation. In addition, this study shows that pulmonary granulomatous inflammation can be quantified biochemically with assays for both NAG and DNA.