Liposomes as carriers of cisplatin into the central nervous system--experiments with 9L gliomas in rats

The anticancer agent cis-diamminedichloroplatinum (cisplatin) has several disadvantages, including extreme nephrotoxicity, rapid binding to plasma proteins, and poor penetration of the central nervous system. In this study liposomes, which can cross the blood-brain barrier, were investigated for their potential in delivering therapeutic agents to brain tumors. Liposomes prepared from egg phosphatidylcholine and cholesterol in a 3:1 molar ratio were divided into 1-ml aliquots and either labeled with 14C or treated with horseradish peroxidase (HRP). The preparations were administered via the carotid artery to rats bearing 9L glioma. Radioactive uptake by brain tumor and normal tissues was measured with a liquid scintillation counter. The presence of HRP-containing liposomes in capillary endothelium and brain tumor cells was demonstrated by light and electron microscopic histochemical techniques. Thirty minutes after injection of 14C-labeled liposomes, radioactive uptake was higher in the spleen than in normal brain, brain tumor, liver, and kidney. Also uptake was greater in brain tumor and lower in kidney than that of cisplatin given alone. Light microscopy showed HRP-containing liposomes in brain tumor tissue 30 minutes after injection. On electron microscopy, liposomes were found to be regularly distributed in surface invaginations and vesicles of capillary endothelial cells. They were also observed within tumor cells. These results indicate that liposomes can penetrate the blood-brain barrier and hold promise as drug carriers in the treatment of brain tumors with cisplatin.

Glycyrrhetinic acid derivatives: anti-nociceptive activity of deoxoglycyrrhetol dihemiphthalate and the related compounds

The possible inhibitory effect of deoxoglycyrrhetol dihemiphthalate (I) and the related compounds (18 beta-olean-9(11),12-diene-3 beta,30-diol) (II) and (olean-11,13(18)-diene-3 beta, 30-diol) III derived from glycyrrhetinic acid has been examined on acetic acid-induced writhing in mice. The compounds inhibited writhing dose-dependently. Their ED50 values were 14, 31 and 22 mg kg-1 for I, II, and III, respectively. The compounds like aspirin, also significantly suppressed PGE2 production in peritoneal fluid together with the writhing response. The results suggests that the analgesic effect of deoxyglycyrrhetol dihemiphthalate and the related compounds is partially due to inhibition of PGE2 production.

[Estimation of fatigue parameter and life-time prediction using SPT diagram for hydroxyapatite coating layer in 37 degrees C distilled water]

Lifetime and survival probability of brittle materials under given conditions of stress distribution, environment and component size can be predicted using an SPT (Strenght-Probability-Time) diagram. The SPT diagram for sintered hydroxyapatite (HAP) coated on the metal substrate via the fused glass was drawn and the safe working stress in 37 degrees C distilled water was estimated. The dynamic fatigue test carried out in 37 degrees C distilled water gave the fatigue parameter n = 19 for sintered HAP. This parameter is constant except that it depends on material and environment, and the greater the value of n, the greater the resistance to fatigue failure. For sintered HAP, therefore, the resistance to fatigue failure under this wet condition is low. To draw the SPT diagram, anchor points were taken from the fracture stress and time-to-failure data measured at 1 mm/min. The SPT diagram obtained suggested that a lifetime of 20 years with survival probability of 99.9% required the safe working stress of less than 3.2 MPa. The effects of accuracy of fatigue parameter on the uncertainty in SPT diagram were estimated.

Anticholinergic action of disopyramide in intestinal smooth muscle of the guinea pig: inhibition of muscarinic receptors (M1 and M2)

Antimuscarinic actions of disopyramide were investigated by measuring the contractile responses of intestinal smooth muscles and ligand binding in cardiac and intestinal membrane preparations. Disopyramide caused a parallel shift of the dose-response curves for acetylcholine, McN-A-343, and carbachol to the right in the guinea pig taenia caeci; pA2 values were 5.4 for acetylcholine, 5.5 for McN-A-343 and 5.9 for carbachol. In the guinea pig ileum, disopyramide competitively antagonized acetylcholine in the contractile responses, having the pA2 value of 6.1. In microsomal fractions of the guinea pig taenia caecum and heart, disopyramide was capable of replacing 3H-QNB; K1 values were 7 x 10(-6) M for the taenia and 2 x 10(-6) M for the heart. These results suggest that disopyramide exerts antimuscarinic action through M1 and M2 receptors with a potency approximately 3 times greater for M2 than M1.

[Effect of RU486 on collagenolytic enzyme activities in immature rat ovary]

To investigate the role of progesterone (P) in the ovulatory process, RU486 (RU) (10mg/kg), an antiprogesterone, was administered to PMS-hCG-treated immature female rats (22 days old). As for the collagenolytic enzymes (CE), the activities of BANA hydrolase and DNP peptidase were measured by using synthetic substrates alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl and DNP Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH, respectively. Serial assays were performed at 0, 2, 4, 6, 7, 8, 9, 10 and 12 hours after the hCG injection. In the control, the CE activities were significantly increased after the hCG injection at 8-9 hours in BANA hydrolase and 7-10 hours in DNP peptidase, respectively. By administering RU concomitant with hCG, the preovulatory increase in the CE activities was totally suppressed. Following the P(10mg/kg) injection at 4 hours after hCG and RU injections, the CE activities showed the greatest recovery, approaching the control range. In the ovulatory process of the rat ovary, P plays an important role through its regulatory effects on the collagenolytic enzymes, and this P effect seems to be most prominent around 4 hours after a LH surge.

Nephritogenic glycoprotein. XIV. A simple isolation method of nephritogenoside

Normal rat renal cortex contains three renal disease-inducing substances, that is, nephritogenoside, FX1A and immunogenoside (a novel renal glycoprotein that has the biological activity to induce only active Heymann nephritis). When renal cortex homogenate was treated with a detergent, Triton X-100, nephritogenoside was not eluted in the supernatant in which massive doses of FX1A and immunogenoside were detected. Thus, we searched for nephritogenoside in the precipitate. The precipitate was solubilized with trypsin, and nephritogenoside was easily and effectively isolated through columns of DEAE-cellulose followed by Bio-Gel A-1.5 m. The purified sample thus obtained is only composed of nephritogenoside, and contains neither FX1A nor immunogenoside. The yield of purified nephritogenoside was 3.8 mg (starting from 150 rats), which is about 5-6 times the recovery of the previous methodology. This newly developed simple method may be useful for the isolation of purified nephritogenoside. The chemical and immunologic properties of the purified sample prepared by the new method corresponded well with those of the nephritogenoside which was obtained by the previous methodology after exhaustive digestions with three proteolytic enzymes from homologous renal cortex.

The inhibitory effect of quinacrine on contractile responses to norepinephrine in isolated rabbit aorta

1. In rabbit aorta, quinacrine, but not indomethacin nor nordihydroguaiaretic acid, inhibited contractile responses to norepinephrine and KCl. Amiloride and nifedipine did not affect the effect of quinacrine. 2. In Ca2(+)-free medium, quinacrine (3 x 10(-6)-10(-4) M) inhibited the norpinephrine response less than that to a subsequent addition of Ca2+. 3. M&B 22, 948, nitroglycerin and forskolin inhibited the Ca2+ response. The effect of quinacrine was inhibited by M&B 22,948, but not by forskolin and potentiated by nitroglycerin. 4. Quinacrine and M&B 22,948 potentiated the nitroglycerin-relaxation. The effect of quinacrine plus M&B 22,948 was not different from that of quinacrine. 5. These results indicate that the effect of quinacrine may be different from that of nifedipine but is related to cGMP.

Measurements of the isometric contractile forces generated by dog periodontal ligament fibroblasts in vitro

One hypothesis for the mechanism of tooth eruption is that the periodontal ligament fibroblasts generate the eruptive force. To assess the force generated, these fibroblasts were obtained by explant culture of ligament from mandibular premolars of a dog and were cultured in collagen gel matrices. The forces generated by them under isometric conditions were continuously measured for 120 h with a strain gauge. At the same time the number of cells in the gel was counted and the force measured was calculated as the force generated by 10(4) cells. Shortly after the start of culture, the force per 10(4) cells increased rapidly; it reached 5.2 X 10(-4) N at 8 h, and then remained at the same level for about 48 h. Our findings suggest that fibroblasts of the periodontal ligament may generate sufficient force for tooth eruption.

[Differences in microvasculature between ethylnitrosourea-induced brain tumor and transplanted 9L cell brain tumor in the rat]

The microvasculature of ethylnitrosourea (ENU)-induced brain tumors and transplanted 9L cell brain tumors were studied in ultrathin sections and by the freeze fracture replica method. The vessels in ENU-induced tumors were similar to human glioma vessels in that they had endothelial tight junctions and increased pinocytotic vesicles. In the 9L cell tumors, the vessels lacked endothelial tight junctions and had fenestrated endothelium. Macroscopically, Evans blue dye penetrated the 9L cell tumors but not the ENU-induced tumors. Judging from the ultrastructure of the microvessels, the ENU-induced tumor appears more suitable as a human glioma model.

[Ultrastructure of capillary permeability in malignant lymphoma]

The ultrastructure of the blood vessels of primary central nervous system malignant lymphoma was studied and compared with those in glial, non-glial and metastatic brain tumors. Five surgical specimens were studied by conventional ultrathin section and freeze-fracture replica techniques. Tumor vessels of various sizes were found. The luminal surfaces of the tumor vessels were irregular and the basal lamina had multiple-layer structure. The perivascular spaces were enlarged and infiltrated with tumor cells. The endothelium had marked infoldings, increased pinocytotic vesicles and fenestrations. The intercellular junctions were short but no obvious opening was seen. On the replica specimen pinocytotic vesicles were calculated on an average of 28 per microns2. The essential features of the blood vessels in primary central nervous system malignant lymphoma were the fenestrated vessels. They resembled the blood vessels found in non-glial and metastatic brain tumors, but were distinctly different from those seen in glial tumors with non-fenestrated vessels.

Biochemical mechanisms of aminoglycoside cell toxicity. II. Accumulation of phospholipids during myeloid body formation and histological studies on myeloid bodies using twelve aminoglycoside antibiotics

Cultured human skin fibroblasts take up aminoglycoside antibiotics into lysosomes to form myeloid bodies. Gentamicin (GM), one such antibiotic, was taken up until the cellular concentration reached an estimated 64 mM on the 3rd day when cells were incubated with 2 mM gentamicin. The rate of release of intracellular GM was high on the first day of incubation and gradually slowed down over the next 4 d. About 50% of the GM remained in the cells even on longer incubation in GM-free medium, suggesting it may irreversibly bind to cellular components. With myeloid body formation, the cellular phospholipid content increased 1.5 times. Bis(monoacyl-glyceryl)phosphate, which is known as a marker of lysosomal phospholipid, phosphatidylcholine and phosphatidylserine showed 250, 162, and 153% increases, respectively. Sphingomyelin was not accumulated, while lysosomal sphingomyelinase was dramatically inhibited. Of 12 different aminoglycoside antibiotics, paromomycin is the most prominent myeloid body-forming antibiotic. The myeloid body-formation is not directly correlated to human nephrotoxicity. On the other hand, the number of myeloid bodies is well correlated to the affinity to the brush border membrane, suggesting that such aminoglycoside antibiotics are taken up easily through cellular endocytosis. The cytotoxic effects of aminoglycoside antibiotics may be due to by their binding to cellular organelles other than lysosomes.

[BANA hydrolase and DNP peptidase activities in the ovulatory process of PMS-hCG treated immature rat]

To investigate the roles of collagenolytic enzymes in the ovulatory process of PMS-hCG treated immature female rats (22 days old), we measured the activities of two of them in the ovary by the using synthetic substrates alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl (BANA) (a collagenolytic cathepsin) and dinitrophenol-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg OH (DNP peptide) (a neutral collagenase). BANA hydrolase activities significantly began to increase after the hCG injection, reaching a peak 8-9 hours later, and then decreased sharply 10 hours later. There was also a significant increase in DNP peptidase activities 7-10 hours after the hCG injection and a significant decrease 12 hours after the injection. The present study has shown that BANA hydrolase and DNP peptidase appear during the ovulatory process of PMS-hCG-treated immature female rats, and that their significant preovulatory increases are contributory to collagenolysis in follicle rupture.

[A case of acute dissecting aneurysm of the aorta in systemic lupus erythematosus]

A 28 year-old female patient who has been diagnosed as having systemic lupus erythematosus (SLE) developed an acute dissecting aneurysm of the aorta (DeBakey type I). The long-term, large dose corticosteroid therapy (i.e., accumulative dose of about 60 g) administered for the treatment of lupus nephritis (WHO class III----IV) was considered to be responsible for a hypercholesterolemia (300-560 mg/dl) and a steroid-dependent hypertension (WHO class III) in this patient. The autopsy findings for the aorta were compatible with atherosclerotic changes but not with lupus arteritis. While atherosclerotic cardiovascular complications have been considered to be rare in patients with SLE, a growing body of evidence suggests that the incidence of such a complication may be increasing along with a dramatic improvement in the longevity of patients with SLE after an introduction of a large dose, long-term corticosteroid therapy.

Adrenocorticotropin and cortisol levels in the plasma of bovine fetuses and neonates

Plasma ACTH and cortisol levels in the bovine fetuses over the period of 5 to 9 months of gestation and in the neonates immediately after birth and at 5 days old were studied. In the bovine fetuses, the plasma ACTH levels ranged from 60.8 +/- 17.8 to 71.3 +/- 19.7 pg/ml over the period of 5 to 7 months of gestation. It increased rapidly to 239.2 +/- 261.5 pg/ml at 8 months and to 406.9 +/- 409.4 pg/ml at 9 months of gestation. In the neonates immediately after birth it decreased to 182.3 +/- 110.7 pg/ml. The plasma cortisol levels ranged from 3.23 +/- 2.12 to 3.85 +/- 2.52 ng/ml over the period of 5 to 8 months of gestation and increased to 8.10 +/- 4.88 ng/ml at 9 months of gestation. It then increased rapidly to 88.35 +/- 42.78 ng/ml in the neonates immediately after birth. The correlation between plasma ACTH and cortisol levels in the fetuses of 5 to 7 months of gestation was not significant, but in the fetuses of 8 and 9 months of gestation and neonates were significant. However, especially immediately after birth, the increase in plasma cortisol occurred without a concomitant rise in plasma ACTH. According to these findings, it is suggested that the pituitary-adrenocortical axis in bovine fetus matures in the later stage of gestation and an increase of sensitivity in the fetal adrenal gland to ACTH may serve as a trigger for the onset of parturition.

Inhibitory effect of a toxin okadaic acid, isolated from the black sponge on smooth muscle and platelets

1. Effects of okadaic acid, a toxin isolated from marine sponges, on smooth muscle contraction and platelet activation were examined. 2. Contractions in rabbit aorta induced by high concentrations of K+ and noradrenaline were inhibited by 0.1-1 microM okadaic acid in a concentration-dependent manner. Spontaneous rhythmic contractions as well as high K+-induced contraction in guinea-pig taenia caeci were also inhibited by 1 microM okadaic acid. 3. High K+-induced contraction in rabbit aorta was accompanied by increased Ca2+ influx measured with 45Ca2+ and increased cytosolic Ca2+ [( Ca2+]cyt) measured with fura-2-Ca2+ fluorescence. Okadaic acid inhibited the contraction without inhibiting Ca2+ influx and produced only a small decrease in [Ca2+]cyt. 4. In a saponin-skinned taenia, Ca2+-induced contraction was not inhibited but rather potentiated by okadaic acid. 5. Okadaic acid, 1 microM, inhibited aggregation, ATP release and increased in [Ca2+]cyt induced by thrombin in washed rabbit platelets. Okadaic acid itself did not change the platelet activities. 6. Okadaic acid did not change the cyclic AMP content of rabbit aorta although the inhibitory effects of okadaic acid were similar to those of cyclic AMP. 7. Although the mechanism of the inhibitory effect of okadaic acid was not clarified in the present experiments, it is suggested that okadaic acid acts by inhibiting protein phosphatases resulting in an indirect activation of cyclic AMP-dependent protein phosphorylation.

Antiulcer activities of glycyrrhetinic acid derivatives in experimental gastric lesion models

Glycyrrhetinic acid (Ia) and eighteen related derivatives were examined for antiulcer activity using stress-induced gastric lesions (restraint plus water immersion at 25 degrees C) in mice and rats as screening tests. Among the compounds tested, dihemiphthalate derivatives of 18 alpha- or 18 beta-olean-12-ene-3 beta,30-diol (IV, IIId), 18 beta-olean-9(11)12-diene-3 beta,30-diol (VIc), and olean-11,13(18)-diene-3 beta,30-diol (VIIc) showed potent inhibition of gastric lesion formation at a dose of 12 or 25 mg/kg (p.o.); carbenoxolone sodium (Ib) significantly suppressed the lesion formation at a dose of 500 mg/kg (p.o.). Further evaluation of the antiulcer activity was carried out mainly for compound IIId. Compound IIId (p.o.) prevented the formation of indomethacin-induced or 0.6 N HCl-induced gastric lesions; the latter antiulcer effect was noted even in the combined treatment with indomethacin, suggesting that the effect occurs independently of endogenous prostaglandins. In contrast, compound IIId had no preventive effect against Shay rat ulcer when intragastrically (i.g.) administered; further, no antisecretory effect was seen by i.g. application in pylorus-ligated rats. Administration of compound IIId for 2 weeks accelerated the healing rate of acetic acid-induced gastric ulcer in rats. No significant change in urine excretion was observed after its consecutive administration for 3 d. These results suggest that dihemiphthalate derivatives (IIId, IV, VIc, VIIc) may produce a strong antiulcer activity, probably by strengthening some gastric mucosal defensive mechanism.

[A case of primary intracranial malignant melanoma with characteristic magnetic resonance imaging]

The authors reported a rare case of primary malignant melanoma in the central nervous system and discussed the findings of MRI. A 60-year-old male was admitted for examinations to discover the cause of his generalized tonic convulsions. On admission, he had neither neurological deficits, nor were there any abnormalities revealed during physical examination. Ct scan disclosed a slightly high-density mass with perifocal edema in the right parietal cortex which enhanced markedly after injection of contrast material. This lesion was hypointense on T1 weighted image of MRI (GE: 1.5 Tesla) and a hyperintense band was observed on the surface of the tumor. On T2 weighted image, the tumor showed iso-hypointensity surrounded by an increased signal area compatible with edema. On August 31, 1988, a gross total removal of the tumor was performed. Microscopically, it was identified as a malignant melanoma. No melanoma was found in other parts of the body during careful examinations, especially in dermatologic and ophthalmologic examinations. Characteristic findings of the hyperintense band on T1 weighted image coincided well with the pathological findings of excessive melanin deposition on the surface of the tumor, and which resulted from the paramagnetic free-radicals in the melanin. MR image may be useful for differentiation of intracranial malignant melanomas from other mass lesions.

Inhibitory effect of a lichen polysaccharide sulfate, GE-3-S, on the replication of human immunodeficiency virus (HIV) in vitro

A sulfate (GE-3-S) prepared by chlorosulfonic acid treatment of GE-3, a partially acetylated beta(1----6) glucan of the lichen Umbilicaria esculenta, inhibited the cytopathic effect of human immunodeficiency virus (HIV) and suppressed the HIV-antigen expression in Molt-4 (clone 8) cells. GE-3-S also suppressed the giant cell formation of HIV-infected Molt-4 cells, and inhibited HIV-induced plaque formation by 50% at the dose of 19.5 micrograms/ml and completely at 250 micrograms/ml in MT4 cells. GE-3-S had no direct effect on the reverse transcriptase of HIV.

[Behavioral pharmacological properties of the novel antidepressant paroxetine, a selective 5-HT uptake inhibitor]

The behavioral effects of paroxetine were investigated in mice and rats in comparison with imipramine and amitriptyline. 1) Locomotor activities were decreased by imipramine and amitriptyline but not by paroxetine in both animal species. 2) Paroxetine antagonized methamphetamine-induced hyperactivity in mice as did imipramine and amitriptyline. 3) Paroxetine showed a more potent antimuricidal effect in raphe-lesioned rats than imipramine and amitriptyline, and it also inhibited muricide in olfactory bulbectomized rats. 4) The immobility of rats in the forced swimming test was markedly decreased by imipramine and amitriptyline, but only slightly by paroxetine. 5) Like imipramine and amitriptyline, paroxetine potentiated the methamphetamine- or L-DOPA-induced stereotyped sniffing, and it inhibited oxotremorine-induced tremor. 6) Paroxetine antagonized reserpine-induced hypothermia, tetrabenazine-induced ptosis, and enhanced ether-induced anesthesia, all less potently than imipramine and amitriptyline. 7) The analgesic action of paroxetine was stronger than that of imipramine and amitriptyline. 8) Paroxetine did not antagonize maximal electroshock- or pentetrazol-induced convulsions and haloperidol- or THC-induced catalepsy in rats. In addition, paroxetine neither exerted muscle relaxation nor affected the shuttle-box type conditioned avoidance in rats. From these results, the behavioral effects of paroxetine, as compared with imipramine and amitriptyline, were characterized by its potent antimuricidal action in raphe-lesioned rats and its weak effect in the forced swimming test and by its less potent muscle relaxant, anticonvulsant, anticataleptic and anesthesia-potentiating actions.

Preparation and characterization of antibodies against 6-O-alpha-D-xylopyranosyl-beta-D-glucopyranose (beta-isoprimeverose), the disaccharide unit of xyloglucan in plant cell-walls

The p-aminophenyl beta-glycoside of 6-O-alpha-D-xylopyranosyl-D-glucopyranose (isoprimeverose), the disaccharide unit of plant xyloglucan, was coupled to bovine serum albumin, and the resulting glycoconjugate was used as an immunogen for the immunization of a rabbit. The immunochemical specificities of the rabbit antiserum raised against the glycoconjugate were characterized by immunodiffusion, quantitative precipitation, and hapten inhibition. After removal of anti-bovine serum albumin antibodies, the antiserum exhibited a specificity for the introduced disaccharide unit of the artificial antigen. The antibody-combining site was also shown to recognize the aglycon portion of the introduced hapten. The antiserum interacted with some xyloglucans, such as those from tamarind seed and the cell wall of pea stem. beta-Isoprimeverose and alpha-D-xylopyranosides were good inhibitors of the xyloglucan-antibody precipitation system, indicating that the antibodies recognize the beta-isoprimeverose unit of the xyloglucan.

[Ultrastructural study of capillary permeability of liposome-encapsulated cisplatin in an experimental rat brain tumor model]

The anticancer chemotherapeutic agent cisplatin (cis-diamminedichloroplatinum) has several disadvantages, including extreme nephrotoxicity, rapid binding to plasma proteins, and poor penetration into the central nervous system. Liposomes would seem to be suitable as carriers of cisplatin to brain tumors. This ultrastructural study was undertaken to identify the capillary permeability of liposome-encapsulated cisplatin in a rat brain tumor model. Brain tumors were induced transplacentally with a single intravenous dose of 50 mg/kg of ethylnitrosourea (ENU). One ml of liposome-encapsulated cisplatin and ferritin prepared from phosphatidylcholine and cholesterol (molar ratio 7:2) was administered via the carotid artery to rats with ENU-induced brain tumors. The tumor platinum content and that of the contralateral hemisphere were assayed by flameless atomic absorption spectrometry. The presence of ferritin-bearing liposomes was demonstrated by electron microscopy of brain capillary endothelium as well as tumor cells. Thirty minutes after drug administration, the average dry-weight platinum concentrations were 3.98 +/- 0.50 micrograms/g within the intracerebral tumors and 0.72 +/- 0.24 micrograms/g in the contralateral hemispheres. Electron microscopic ultrastructural study, which can distinguish ferritin-bearing liposomes from cell materials, demonstrated the presence of liposomes containing ferritin in both cell surface folds and capillary endothelial cells and also within tumor cells. An enlarged electron micrograph of a liposome with a diameter of approximately 0.2 micron suggested the presence of ferritin molecules in the lamellar structure. Liposome-encapsulated cisplatin is apparently able to pass the blood-brain barrier and should be useful in the chemotherapy of glioma.

Accessory cell activity of monocytes in anti-DNA antibody production in systemic lupus erythematosus

Depletion of monocytes from peripheral blood mononuclear cells of patients with systemic lupus erythematosus (SLE) resulted in a decreased anti-DNA antibody synthesis in vitro. The addition of monocytes restored the response by lymphocytes and the maximum response in the presence of 2.5-8% of monocytes, whereas greater than 15% of monocytes caused rather decreased antibody responses. In order to further evaluate the role of monocytes on an anti-DNA antibody synthesis, we designated an accessory cell index, based on reconstitution experiments using isologous SLE lymphocytes, and compared it in active or inactive SLE and controls. The studies revealed that active SLE monocytes enhanced spontaneously occurring anti-DNA antibody synthesis by SLE lymphocytes. These results indicate that SLE monocytes actively participate in spontaneously occurring anti-DNA autoantibody synthesis in humans.