Circulating immune complexes in the sera and ascites of hepatocellular carcinoma or chronic hepatitis patients

Circulating immune complexes (CIC) in the sera or ascites of hepatocellular carcinoma (HCC), chronic hepatitis patients and normal healthy persons were measured by polyethylene glycol (PEG) and C1q solid-phase microassay (C1q-SPMA). Both the PEG and C1q-SPMA methods showed the serum CIC levels of HCC patients were significantly higher than those of chronic hepatitis patients and of normal persons. The CIC levels of chronic hepatitis patients were also significantly higher than those of normal persons as detected by PEG method but not by C1q-SPMA. The ascites from HCC patients also had CIC. But the amount of CIC in ascites was significantly lower than those of the serum from the same HCC patients. These results suggest that the increase of CIC may play some pathological role in the HCC patients.

Cytomegalovirus viremia increases with progressive immune deficiency in patients infected with HTLV-III

Cytomegalovirus (CMV) viremia was studied in 15 homosexual patients [two healthy, nine with the acquired immune deficiency syndrome (AIDS), five with the AIDS-related complex (ARC)], in one patient with transfusion-related AIDS, and in four individuals with cancer or connective tissue disorders. While CMV viremia was absent in the latter patients, in the healthy homosexuals, and in three stable ARC patients, it was present in clinically-deteriorating ARC patients and in all nine AIDS patients. Some CMV isolates caused limited proliferation of fibroblasts in the culture medium. The rapidity and ease of CMV isolation from leukocytes of patients at different stages of infection with human T-lymphocytotropic virus type III (HTLV-III) indicate that the CMV titer in leukocytes increases as immune deficiency worsens. In ARC patients CMV viremia may be predictive of clinical complications in the next 3 months. In AIDS patients CMV viremia at high titer was an unfavorable prognostic sign.

Expression of c-myc gene in human hepatoma

The level of c-myc transcript was examined in liver samples from seven hepatoma patients. Transcripts were detected in all the normal liver parts examined; in contrast, in two hepatoma parts, there was a dramatic reduction in c-myc transcripts. The restriction enzyme pattern of c-myc gene appeared the same among samples. The data suggest that c-myc gene expression might not be required for the maintenance of the tumor state in human liver carcinogenesis.

Pancreatic islets contain the M2 isoenzyme of pyruvate kinase. Its phosphorylation has no effect on enzyme activity

To determine which of the major isoenzymes of pyruvate kinase pancreatic islet pyruvate kinase most resembled, it was compared to pyruvate kinase from other tissues in kinetic and immunologic studies. The pattern of activation by fructose bisphosphate and the patterns of inhibition by alanine and phenylalanine were most similar to those of the M2 isoenzyme from kidney and were dissimilar to those of the isoenzymes from skeletal muscle (type M1) and liver (type L). The islet pyruvate kinase was inhibited by anti-M1 pyruvate kinase serum (which crossreacts with the M2 isoenzyme), but not by anti-L pyruvate kinase. These results are most consistent with islets possessing predominantly, if not exclusively, the M2 isoenzyme of pyruvate kinase. We previously showed that rat pancreatic islet cytosol contains protein kinases that can catalyze a calcium-activated phosphorylation of an endogenous peptide that has properties, such as subunit molecular weight and isoelectric pH, that are identical to those of the M2 and M1 isoenzymes of pyruvate kinase, and that islet cytosol can catalyze phosphorylation of muscle pyruvate kinase. In the present study it was shown that incubating islet cytosol with ATP under conditions known to permit phosphorylation and inhibition of liver pyruvate kinase did not affect the islet pyruvate kinase activity. It is concluded that phosphorylation of the islet pyruvate kinase has no immediate effect on enzyme activity.

Evidence for phosphorylation of pancreatic islet pyruvate kinase

Rabbit pancreatic islet cytosol catalyzes the calcium-activated phosphorylation by [gamma 32P]ATP of a protein with a molecular weight of 57,000 that is precipitated with antipyruvate kinase antibodies. We were unable to demonstrate that phosphorylation in the presence of calcium or cAMP had any immediate effect on rat pancreatic islet pyruvate kinase activity. This finding is consistent with our inability to confirm the finding of others that pancreatic islets contain phosphoenolpyruvate carboxykinase activity (Diabetes, 34:246, 1985). Since the carboxykinase catalyzes phosphoenolpyruvate formation and pyruvate kinase catalyzes essentially the opposite reaction, if the carboxykinase were present in the beta cell, pyruvate kinase would need to be inhibited to prevent recycling of phosphoenolpyruvate.

Activation of pancreatic islet myosin ATPase by ATP and actin

Previous work from our laboratory indicated that pancreatic islets contain myosin light chain kinase, a calcium- and calmodulin-activated enzyme. This enzyme catalyzes phosphorylation of myosin which, in tissues containing smooth muscle, is believed to permit the ATPase of myosin to be activated by actin. The current report shows that incubating islet cytosol with ATP under conditions that should permit phosphorylation of myosin markedly enhances islet myosin ATPase activity in the presence of actin. It has been suggested that contractile proteins power insulin granule movements in the beta cell. Phosphorylation of myosin may be one of the means of coupling stimuli to insulin secretion.

Cellular and antigenic properties of cultured normal and fetal brain and glioma cells

The immunological and cellular properties of cultured normal and fetal brain cells as well as glioma cells were compared. They were grown successfully in tissue culture media. Results from the growth properties and karyotype analysis indicated that cultured cells from normal and fetal brain tissues were normal and could be passaged limited times. The fetal brain cells had a longer life span than normal brain cells in the culture and their morphology exhibited variations according to cell passages. Two glioma cell lines, designated as G-5-T and G-9-T were established. The G-5-T and G-9-T had different morphology. Both G-5-T and G-9-T formed colonies in the soft agar. However, only G-9-T cells grew as large tumors in nude mice. Neither cell line secreted CEA, AFP and did not contain GFAP and S-100 protein. As measured by the 51Cr cytotoxicity assay, G-9-T but not G-5-T cells possessed D/DR antigens.

Characterization of cell surface adenosine 3',5'-monophosphate-binding proteins in Y-1 mouse adrenal tumor cells

Adrenal cortical cells are known to export cAMP and have binding proteins and cAMP-dependent protein kinase activity associated with their plasma membranes. Because these properties suggest a function for extracellular cAMP, we have undertaken a search for specific cell surface receptors for this cyclic nucleotide. Y-1 mouse adrenal tumor cells actively export cAMP by an energy-dependent process. Analysis of Scatchard plots of the equilibrium binding of [3H]cAMP to these cells indicate the existence of two classes of cAMP binders: one with high affinity (ka = 2.9 X 10(9) M-1) and another with low affinity (ka = 7.0 X 10(7) M-1). The cell surface localization of these binders was established by the sensitivity of both the [3H]cAMP-binding proteins and the [32P]8-N3-cAMP photoaffinity labeled proteins of intact cells to mild trypsin digestion and by the surface distribution of a BSA-O2-monosuccinyl cAMP-gold complex revealed by electron microscopy. Analysis of radioautograms of cell surface cAMP-binding proteins from confluent monolayer tumor cells, photoaffinity labeled with [32P]8-N3-cAMP and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two major 32P-labeled protein bands which were indistinguishable from the 49,000 and 55,000 mol wt regulatory subunits of the cytosolic protein kinase isoenzymes of this cell. These observations along with the demonstration of cell surface, cAMP-dependent protein kinase activity in the mouse adrenal tumor cell strongly suggest that these cAMP-binding proteins function as regulatory proteins for cell surface protein kinases.

Do pancreatic islets contain significant amounts of phosphoenolpyruvate carboxykinase or ferroactivator activity?

Phosphoenolpyruvate carboxykinase activity was measured in rat pancreatic islet cytosol and mitochondria. No carboxykinase activity was detected under a variety of conditions, including those that increase phosphoenolpyruvate carboxykinase activity in nonislet tissues, such as starving animals or incubating the islet extracts with Fe2+ or Mn2+ before assaying for enzyme activity. The amounts of islet cytosol protein used exceeded those of liver in companion assays used as controls. It was calculated that if islet phosphoenolpyruvate carboxykinase activity was 0.005 that of liver, or 1 X 10(-5) as high as pyruvate kinase activity in islets, it should have been detected in the assays used. Ferroactivator is a protein that permits Fe2+ to activate phosphoenolpyruvate carboxykinase and it is ubiquitous to many tissues that do and even do not contain the carboxykinase. Ferroactivator activity was not detectable in pancreatic islets. Pyruvate kinase, an enzyme that catalyzes a reaction that is essentially the opposite of that catalyzed by phosphoenolpyruvate carboxykinase (i.e., phosphoenolpyruvate formation), is plentiful in islet cytosol. Therefore, even if phosphoenolpyruvate carboxykinase activity is present in pancreatic islets, it is so low that it is unlikely that phosphoenolpyruvate formation would be favored and the contribution of the carboxykinase to intracellular carbohydrate metabolism must be quantitatively unimportant.

Endogenous opioid peptides in intrapartum uterine blood

Endogenous opioid peptides have consistently been reported to exert significant influence on several parameters of reproductive physiology, including tolerance to pain, release of prolactin, pleasurable behavior patterns, and appetite satiety. Immunoreactive endorphins measured in several hundred samples of postpartum uterine blood had a mean value of 190 pg/ml and a range of 60 to 520 pg/ml. Individual values in 100 mothers who were delivered at the Northwest Hospital failed to correlate with doses of postpartum pain medications, infant feeding patterns, and recorded estimates of maternal bonding behavior. Postpartum "blues" may be related to stress-induced depletion of endorphinergic systems.

Biologic properties of three newly established human esophageal carcinoma cell lines

Three epithelial cell lines, CE-48T/VGH, CE-69T/-VGH, and CE-81T/VGH, were established from human squamous cell carcinoma of the esophagus. The cells were polygonal with a high nucleus-to-cytoplasm ratio. Many cells were multinucleate. Electron microscopy revealed the presence of tonofilaments and desmosomes. Chromosome analysis showed that these 3 cell lines were heteroploids of human origin. When transplanted into BALB/c (nu/nu) mice, CE-69T/VGH and CE-81T/VGH produced tumors, the histology of which proved to be carcinomas. All 3 cell lines secreted carcinoembryonic antigen. However, the secretion patterns were different. These 3 cell lines may provide useful models for the study of human esophageal cancer.

Circulating immune complexes in cervical cancer patients as detected by C1q binding

In a retrospective study in women with cervical cancer, circulating immune complex levels were measured by radioimmunoprecipitation with 125I-C1q. Sera from 46 patients with cervical cancer and 35 normal controls were examined. Significantly higher levels of immune complexes were detected in cancer patients compared with controls. Mean value of binding capacity in patients was 49.8%, and by contrast, in the controls was 27.4% (two-tail test = 0). Increases in tumor mass were associated with high levels of circulating immune complexes. The presence of immune complexes in circulation statistically correlated with disease activity, however, the assay used still had limited value for diagnosis or aiding in therapeutic decisions. Nevertheless, the future holds promise for such uses.

Complement-mediated binding of monocytes to intermediate filaments in vitro

An in vitro model for complement (C)-mediated monocyte binding to injured cells is described. This model is based on the property of cytoskeletal intermediate filaments (IMF) to directly and independently activate serum C via the classic pathway. Fixed monolayers of cultured fibroblasts, endothelial cells, and L 132 epithelial cells were each used as targets. The authors first subjected the target cells to limited detergent extraction in order to make permeable the plasma membrane, and then exposed them to normal human serum. Immunohistologic analysis demonstrated that this process permitted binding of clearly demonstrable amounts of C1q, C4, and C3 to cytoplasmic loci containing IMF. The target cells were then incubated for various lengths of time with peripheral blood mononuclear cells containing about 20% monocytes. Preferential binding of monocytes was demonstrated by histochemical and immunologic staining methods. Only 5% of the attached cells were B lymphocytes. By transmission electron microscopy the attached cells exhibited typical monocyte morphology. Attachment to target cells involved contact with areas rich in IMFs and led to signs of activation; both an increased number of cytoplasmic organelles and phagocytosis of target cell material were observed. Attachment of monocytes was clearly dependent on serum treatment of the targets; the ratio was 10:1 when compared with control experiments using target cells that had not been incubated with serum. It is reasonable to consider that bound monocyte-derived macrophages associate with activated C components, most likely C3b fragments or C1q, for which monocyte surface receptors have been established. This mechanism may be triggered in various inflammatory reactions involving cell and tissue injury and as an event in the final stages of macrophage-mediated removal of injured or nonviable cells.

[A new human hepatoma cell line: establishment and characterization]

We have grown a human hepatoma cell line, designated as HA22T/VGH, from a 52-yr-old male hepatoma patient since July 1, 1980. This cell line has been subcultured more than 100 passages. The chromosome analysis of HA22T/VGH indicated that the chromosome numbers varied from 70 to 146, with the mode of 73. Methylcellulose soft agar assay showed that approximately 40% of the HA22T/VGH cells formed colonies. The HA22T/VGH produced tumors in nude mice. Histopathological studies of the tumor revealed the arrangement of hepatoma. Detected by the complement fixation method HA22T/VGH cells secreted ceruloplasmin, Factor B, C3, C4, Gc-globulin and alpha 1-acid-glycoprotein. These cells contained the liver associated enzymes: alanine amino transferase, tyrosine amino transferase and gamma-glutamyl transferase. HBsAg and alpha-fetoprotein were not detectable in the HA22T/VGH culture media or cell lysates by the radioimmunoassay.

Immunoreactive endorphin peptides and prolactin in umbilical vein and maternal blood

Immunoreactive endorphin peptides (ir EP) and prolactin (PRL) were measured by radioimmunoassay in venous blood from the umbilical cord of 86 neonates, 23 postpartum mothers, and 40 randomly selected blood bank donor control subjects. We also assayed these hormones in serosanguineous placental tissue fluid following delivery. The data suggest both ir EP and PRL are elevated during both processes and that placental chemistry may be implicated in blood levels of these hormones. Some biological and clinical aspects of placental opiates are discussed.

Pancreatic beta-endorphin-like polypeptides

Acid extracts of porcine pancreas acetone powders (but not of other tissues) have been shown to contain material which will react firstly in a radioimmunoassay for beta-endorphin, and secondly, compete with 3H-Naloxone and 3H-enkephalinamide in the radio-receptor assay. This material had a molecular weight of approximately 7,000 as judged by both P-10 and G-50 exclusion chromatography, even in the presence of 4 M urea. The G-50 partially purified and desalted fraction demonstrated a dose-dependent analgesia in mice and also influenced mouse behavior in vivo in a manner analogous to that produced by synthetic human beta-endorphin.

Permeability factor contaminating hyaluronidase preparations

Both crude and highly purified testicular hyaluronidase preparations have been shown to contain a component which increases the permeability of the microcirculation in rat skin. This permeability activity had an isoelectric point of 7.4 while hyaluronidase was 9.4. It also could be separated from hyaluronidase by acrylamide gel electrophoresis. The permeability factor was not inhibited by serum and may explain previous observations that hyaluronidase preparations decrease the ischemia and necrosis appropriate to experimental myocardial infarction in vivo.

Macromolecular, anionic pulmonary permeability factor

Aqueous extracts of fresh or acetone-powdered calf lung have been found to contain a factor which increases the permeability of the microcirculation when injected into the skin of rats. This permeability factor, which is not found in similar extracts of muscle or kidney, was concentrated by Amicon ultrafiltration at a molecular weight range of between 50,000 and 100,000 daltons and via isoelectric focusing at an IEP of pH 4.2. After preparative acrylamide gel electrophoresis, this permeability factor was homogeneous by electrophoretic criteria and in SDS acrylamide gel electrophoresis had a molecular weight of approximately 82,000 daltons. This apparently homogeneous permeability factor from lung was inhibited by pepstatin, and yet possessed no acid proteolytic activity against any substrate. Its activity was completely inhibited by pretreatment of the animals with antihistamines. This pepstatin-inhibitable permeability factor was found largely in the lysosomal fraction of fresh lung and could also be obtained by extraction of large amounts of alveolar "washout" macrophages. Since macrophages, during phagocytosis, are known to leak significant quantities of their lysosomal contents, the fact that one of these components is a material which could release histamine from mast cells and thereby increase locally the permeability of the microcirculation may be of importance in the defense system of the lung.

Pulmonary macrophage growth factor

Pulmonary macrophage growth factor (MCF) can be purified from the "used" serum-free medium of cultures of mouse lung cells by concentration and dialysis over a 30,000-dalton Amicon ultrafilter and subjecting the retentate to isoelectric focusing. This yields a protein fraction with an isolelectric point of pH 4.2, which contains all the MGF activity. Upon electrophoresis of this fraction in analytical gels, one large and four small bands could be visualized. All bands were biologically active. This same "heterogenous" fraction ran as one band (mol wt 68,000) in SDS analytical gel electrophoresis, suggesting the ordered aggregation of this monomer. This was confirmed by reelectrophoresis of the first (and largest) band demonstrating the same 5-banded pattern as the initial material.

Normocholesterolemic dysbetalipoproteinemia with xanthomatosis

A patient is described who has marked palmar xanthomatosis associated with a normal concentration of plasma cholesterol. Analysis of xanthomas revealed them to contain large quantities of cholesterol with both intra- and extracellular lipids. Examination of plasma lipoproteins showed them to be consistent with a pattern of dysbetalipoproteinemia (Type III hyperlipoproteinemia). VLDL had beta-mobility on electrophoresis, a high cholesterol/triglyceride ratio, and increased apoprotein B. However, arginine-rich apoprotein was not increased in VLDL, in contrast to hypercholesterolemic patients with the Type III pattern. Nevertheless, the E3 subfraction of the arginine-rich apoprotein was virtually absent, which is characteristic of dysbetalipoproteinemia. Cholesterol and bile acid synthesis were in the normal range. Thus, of particular interest was the development of severe xanthomatosis without hypercholesterolemia in this patient. Therefore, tissue accumulation of cholesterol was apparently the result of a qualitative abnormality in lipoproteins and not due to an excess of plasma cholesterol.

Interactions of native and modified human low density lipoproteins with human skin fibroblasts

125I-labeled low density lipoprotein (LDL) covalently bonded to Sepharose beads was not degraded by normal human fibroblasts nor did it trigger inhibition of sterol synthesis. The Sepharose beads loaded with LDL bound very tightly to the surface both of normal fibroblasts and fibroblasts from a subject with homozygous familial hypercholesterolemia; control Sepharose beads (activated sites covered with glycine) did not adhere to either cell type. LDL was extracted by a modification of the method of Gustafson (Gustafson, A. (1965) J. Lipid Res. 6, 512-517), so as to remove essentially all cholesterol, cholesterol ester and triglyceride. This modified LDL was bound, internalized and degraded as well as or better than native LDL. However, it failed to suppress sterol synthesis. These results provide additional evidence that the sterol moiety of the LDL is the key component affecting sterol synthesis. They also imply that the neutral lipids of LDL play a minor role in the binding of LDL to cell membranes and that the apoprotein rather than molecular size and shape is the critical factor.

The biochemistry of lymphocyte-derived mediators of immunological inflammation

Evidence is presented to indicate that there exists in lymphoid tissue, as a result of transforming lymphocytes, a new lymphokine which is chemotactically specific for lymphocytes, called 'lymphotactin'. Lymphotactin has been purified to electrophoretic homogeneity; has a molecular weight of 10,500 D and an isoelectric point of 5.9. Its role in amplifying the immune defense system by recruitment of naive lymphocytes into propinquity with the challenging antigens is suggested. Purification of macrophage migration inhibitory factor from thymus extracts to electrophoretic homogeneity leads to a compound of molecular weight of 36,500 D and an IEP of 6.9. Chemically it contains sialic acid and o-methyl glucopyranoside as its only carbohydrates. Purified MIF activates the macrophage phagocytically. Skin reactive factor and lymph node permeability factor have been isolated and purified and are found to be inhibited by pepstatin and antihistamine and to have an isoelectric point of pH 4.2 and a molecular weight of 50,000--100,000 D. It is believed that this anionic permeability increasing agent actually arises from the lysosomes of macrophages and lymphoblasts (the normal small lymphocyte having essentially no lysosomal organelles). The mononuclear cell infiltration characteristic of crude SRF and LNPF may proceed from their being contaminated with lymphotactin.

The purification and characterization of a lymphokine chemotactic for lymphocytes--lymphotactin

Aqueous extracts of the thymus from vaccinated calves contain a protein specifically chemotactic for lymphocytes (lymphotactin). Lymphotactin has been isolated and purified by ethanol fractionation, ultrafiltration, isoelectric focusing, and preparative acrylamide gel electrophoresis. Its isoelectric point is 5.9, and the molecular weight by both SDS electrophoresis and exclusion chromatography is about 10,500. The purified sialoprotein is homogeneous at three different pH's in acrylamide gel electrophoresis. As little as 1 microgram of this material intraperitoneally wlll produce massive lymphocyte infiltration within 4 h in vivo.

Synthetic glycolipid adjuvants

In the course of the organic synthesis of model compounds similar in some features to the lipid moiety of endotoxic lipopolysaccharide (LPS), Nacylated-D-glucosamine derivatives were prepared. One of these, N-palmitoyl-D-glucosamine, has been previously found to be mitogenic for athymic nude mouse B cells. This and other N-acylated homologs were tested for adjuvant activity in the immune response to human gamma-globulin (HGG) and sheep red blood cells (SRBC) in mice. Comparable or superior enhancement of the immune response was obtained for these glycolipids when compared to LPS in assays measuring anti-SRBC or HGG hemagglutinin titers. In the determination of hemolytic plaque formation, considerable adjuvant effect was shown by the lauroyl derivative, and less but still significant enhancement was achieved by the N-palmitoyl-D-glucosamine. In the rosette formation assay, in addition to the above two glycolipids, N-oleyl-D-glucosamine showed good adjuvant effect. In the latter two assays, the LPS was a superior adjuvant as compared to the synthetic glycolipids. The radiation protective effect of some of the better synthetic adjuvants was also investigated in mice. It was found that although LPS was more effective in this assay, the N-myristoyl-D-glucosamine and N-decanoyl-D-glucosamine compounds gave a definite protection, since up to 40% of the lethally irradiated (700 R) mice survived.

Relationship of structure to function in bacterial endotoxins: serologically cross-reactive components and their effect on protection of mice against some gram-negative infections

Rabbit antisera were prepared against the heptoseless Re mutants, Salmonella minnesota R595 and S. typhimurium SLI102, as well as against purified R595 glycolipid coated on autologous erythrocytes. The antisera cross-reacted with the endotoxic glycolipids extracted from Re mutants of various bacterial strains, including S. minnesota R595, S. typhimurium SLI102, Escherichia coli D3Im4, E. coli D2If2 and E. coli F515, as shown by passive haemagglutination and gel diffusion tests. The anti-Re sera also cross-reacted with the RESI preparations (a purified 'lipid A' fraction) from the endotoxic lipopolysaccharides of various heterologous smooth Gram-negative bacteria including Serratia marcescens. Psuedomonas fluorescens and E. coli 0127. However, the same antisera failed to protect mice against infection by Gram-negative bacteria such as Klebsiella pneumoniae type II, S. typhi 0901, P. aeruginosa 119 and E. coli. The results suggest that although the lipid moieties of the lipopolysaccharides in the cell wall of Gram-negative bacteria share cross-reactive immunodeterminant groups, these groups may not be accessible to antibody against them.

The inhibition of macrophage migration inhibtory factor (38485)

Analogs of EACA were capable of inhibiting the in vitro activity of macrophage migration inhibitory factor (MIF). The most active analog of EACA in terms of MIF inhibition had four methyl groups separating an acetylated amino group from a free carboxyl group. This compound, acetylated 5-amino valeric acid, was capable of inhibiting completely MIF activity in vitro at a concentration of less than 10-6 M without demonstrating any appreciable antitryptic activity, even at 10-3 M. Antitryptically active EACA did not inhibit MIF except at very high concentrations (10-2M). Further, the most purified preparations of MIF obtained from aqueous extracts of thymus that we have studied contained no significant proteolytic activity upon denatured hemoglobin at pH 3-8. Therefore, we do not correlate anti-tryptic with anti-MIF activity in vitro.

Comparison of the chemical structure and biological activities of the glycolipids of Salmonella minnesota R595 and Salmonella typhimurium SL1102

It has been assumed in the past that the lipid moieties of endotoxic lipopolysaccharides are quite similar if not identical. This has been tested in the reported work here, where the chemical composition and biological activities of the glycolipids of two heptoseless Re mutants, Salmonella minnesota R595 and Salmonella typhimurium SL1102, have been studied and compared. The two glycolipids, extracted with chloroform-methanol (4:1), showed identical thin-layer chromatographic patterns. The molar ratios for hexosamine, fatty acids, phosphorus, 2-keto-3-deoxyoctonate, total amines, and total nitrogen of the purified glycolipids were in the same range, but small differences could be established. Both glycolipids contained the same major fatty acids, i.e., lauric, myristic, palmitic, and 3-hydroxymyristic acids, in similar but not identical ratios. On paper electrophoresis, the acid hydrolysates of the two glycolipids showed analogous components. In the determination of molecular weight, whereas S. minnesota R595 glycolipid did not show concentration dependence, the molecular weight measured for S. typhimurium SL1102 increased with its concentration. The molecular weight of the fully endotoxic R595 glycolipid has been found to be 17,000 +/- 1,500. Both glycolipids showed similar activities in the Shwartzman skin reaction, Limulus-lysate clotting assay, mouse lethality, and enhancement of nonspecific resistance, but the R595 preparation appeared to be more active on a weight basis in some parameters than SL1102. Using passive hemagglutination, we observed cross-reactivity between the glycolipids. In the gel-diffusion test, they revealed clear identity. The antiserum against S. minnesota R595 neutralized the Shwartzman skin reactivity not only of R595 but also of SL1102 glycolipid. These results confirm that there are identical immunodeterminant group(s) in the two glycolipids. On the other hand, chemical analytical data for two glycolipids showed only similarities, indicating that although both glycolipids are of comparable chemical nature, differences between them exist.