bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complement-Dependent Lysis of RNA Tumor Viruses
Authors: Cooper N. R. , Welsh R. M. , Jensen F. , Oldstone M. B. A. 
Published: January 2023

Abstract
Although RNA tumor viruses (oncornaviruses) infect and are associated with malignancies in numerous species, they have been difficult to detect in human cancers. We found that fresh normal human sera inactivate Moloney (MLV), Rauscher (RLV), and AKR leukemia viruses, Moloney sarcoma virus, feline leukemia virus and simian sarcoma virus (Welsh, Cooper, Jensen, and Oldstone, Nature 257:612, 1975). Inactivation was due to viral lysis as RNA dependent DNA polymerase (RDDP) and RNA were released during the reaction. Fresh guinea pig and rabbit C and heated human sera did not have these properties. Antibody (Ab) did not seem to be involved since 1) agammaglobulinemic sera released RDDP, 2) cytolytic potential was not removed by absorption with cells expressing MLV, and 3) heated sera did not sensitize MLV for lysis by fresh guinea pig C. Viral lysis did not occur in human sera deficient in C2 or C4.
Genetic Control of C3 Levels in Mice
Authors: Ferreira Arturo , Nussenzweig Victor 
Published: January 2023

Abstract
At 2 to 3 weeks of age, but not at 9 weeks, AKR/J (H-2k) mice have higher C3 levels than DBA/2J (H-2d) and the F1 hybrids have intermediate levels. We recently completed analysis of linkage tests between C3 levels and H-2 genotypes in newborn mice. Screening of 202 mice of backcrosses (AKD2F1 × DBA/2J and AKD2F1 × AKR/J) and of F2 generation (AKD2F1 × AKD2F1) at 21 days of age confirmed a previous finding of significant differences (p &lt; 0.001) between C3 levels of mice with different H-2 genotypes and, in addition, strongly suggests that very few independently segregating pairs of alleles are involved. Measurements of C3 levels of congenic lines of mice which bear five standard, independent H-2 haplotypes showed that they can be classified into at least two groups: C3-high (H-2f, H-2k, and H-28) and C3-low (H-2d and H-2b).
Isolation of Soluble C3 Receptor Activity from Rabbit Platelets
Authors: Henson Peter M. , Neshyba Janice 
Published: January 2023

Abstract
Interaction of the C3 receptor on rabbit platelets with C3-bound EA or zymosan (ZC3) results in adherence of the platelets and the initiation of an active secretory response. The secretion apparently involves the activation of a serine esterase as an early or initial step. Experiments were undertaken to isolate and characterize the C3 receptor in order eventually to determine its relationship to the esterase. Washed rabbit platelets were disrupted in sucrose by either homogenization or sonication. Platelet membranes (identified by 5′nucleotidase or previously bound 125I-antiplatelet antibody) were isolated on continuous or discontinuous sucrose gradients. Alternatively, the homogenate was passed through Sepharose-4B and the material excluded (containing the membranes) was employed.
Two assays were used to detect C3 receptor activity. Both, in addition, serve to define the nature of the C3 receptor. The assays are quantitative and reproducible and comprise: 1) inhibition of the binding of 51Cr-platelets to ZC3 or 2) inhibition of the ZC3-induced secretion from platelets.
Activation of Complement Through the Alternate Pathway by Microbial Glucans
Authors: Inai S. , Ebisu S. , Kato K. , Kotani S. 
Published: January 2023

Abstract
Complement and its components levels in the normal human serum treated with glucans of oral streptococcus and of the other microbials were studied. It was found that the enzymatically synthesized water-insoluble glucan of Streptococcus mutans OMZ 176, containing consecutive α-1.3 (60%) and branched α-1.6 (35%) linked glucose units, was a potent activator of the alternate pathway. CH50 in the serum treated with more than 200 µg/ml of OMZ 176 glucan was less than 5 units, and no significant reductions in the early acting components were observed, but considerable decrease in C3 and almost complete reduction of C5 were found. These complement component profiles were similar to that of serum treated with zymosan. Glucan of S. mutans OMZ 65, which is considered to have almost the same structure to OMZ 176 glucan, could also activate the alternate pathway. S. mutans Ingbritt insoluble glucan which contained less α-1.3 linkages than that of OMZ 176 glucan was less active than OMZ 176 glucan.
Two Mechanisms for the Activation of Serum Complement by Bacterial Lipopolysaccharides: A Role for Lipid A in Only One of Them
Authors: Morrison David C. 
Published: January 2023

Abstract
Preparations of lipopolysaccharide (LPS) from different bacterial sources vary significantly in their relative content of lipid A (LA) and polysaccharide (PS). As a number of biologic properties of LPS have been attributed to the LA region of the molecule, and as isolated LA has been demonstrated to activate complement, the relationship between the LA content of LPS and its anticomplementary activity was examined. Activation was determined by a) reduction in hemolysis of sensitized erythrocytes, b) alteration of the electrophoretic mobility of C3 in normal (NHS) and C2-deficient (C2-def) human serum, and c) consumption of early complement components C1, C4, and C2. Two antigenically similar preparations of LPS from Escherichia coli 0111:B4, which vary significantly in their relative ratio of LA:PS (LPS-I, low LA:PS and LPS-II, high LA:PS) were used. In addition, LPS from E. coli 055:B5, which is structurally similar but antigenically unrelated to LPS-I; LPS from Salmonella minnesota R595, which contains only LA and a trisaccharide; and purified LA itself were also examined.
Normal Values of CH50 and Individual Complement Components
Authors: Opferkuch W. 
Published: January 2023

Abstract
Sera were obtained from 605 clinically healthy human individuals. On these sera the following studies have been performed: determinations of the CH50 and C1 inactivator activity and molecular titrations of C1, C4, and C2. The protein concentration of C4, C3, C1 inactivator and C3-proactivator in the sera was determined by means of the Mancini technique. At the same time the reproducibility of these tests was investigated. It was found that the standard error of each individual test was about 7 to 15% of the mean value. Only in the determinations of the C1-inactivator activity there was a standard error of about 25%.
Comparing the male and the female populations, no statistically significant difference in their mean values and distribution curves could be observed. With increasing age, however, a statistically significant increase in the Ch50 titer, levels of C1, C4, C2 activity and C4 and C3 serum protein concentrations could be found in the female population.
Role of Complement in Enhanced Tumor Growth in Nude Mice
Authors: Shearer W. T. , Atkinson J. P. 
Published: January 2023

Abstract
Traditionally, the role of complement (C) in the regulation of malignant cell growth has been thought to be one of cell destruction by cytolysis. A new perspective was achieved when it was discovered that C markedly augmented the phenomenon of immunologic enhancement in vitro. Thus, anti-L cell antibody exerted a biphasic effect upon L (transformed mouse fibroblast) cell growth with high concentrations inhibiting growth and low concentrations stimulating growth. Complement augmented both cytotoxic and cytostimulatory effects of antibody (Ab) upon L cells in vitro. This report represents evidence to suggest that C exerts a synergistic effect with Ab in the stimulation of tumor growth in vivo.
Congenitally athymic (nude) mice were depleted of C3–C9 C components by the repeated i.p. injections of Cobra venom factor (CVF) and given 40 µl of either control rabbit serum (CR) or rabbit anti-L cell antiserum (AL) on day -1.
Linkage of C4 Deficiency to the Major Histocompatibility Locus in the Guinea Pig
Authors: Shevach E. , Green I. , Frank M. M. 
Published: January 2023

Abstract
C4 deficient (C4D) guinea pigs have a deficiency in C4 synthesis that appears to be due to a structural gene defect. Previous work has demonstrated that inheritance of this defect follows simple Mendelian laws. This report demonstrates linkage between C4D and an antigen controlled by a gene in the major histocompatibility complex of the guinea pig. Recent studies have defined a major histocompatibility locus (MHL) in the guinea pig (B) which appears to be equivalent to the D or K loci in the mouse, as well as a second region which resembles the mouse Ia. Four alleles of the B locus have been identified: B.1, B.2, B.3, B.4. Preliminary screening of the NIH multipurpose colony (the colony in which C4D was first observed) showed that 5 to 10% of the animals were homozygous for the B.1 antigen; the remaining animals had detectable B.3 antigen by serologic testing.
Purification, Subunit Structure, and Isolation of Peptides from Limit Tryptic Digests of Human C3
Authors: Tack B. F. , Prahl J. W. 
Published: January 2023

Abstract
A method for the preparative level purification of human C3 from plasma has been developed. Initial fractionation of plasma with polyethylene glycol (PEG) yields a protein fraction precipitating between 5 and 12% (w/v) PEG that contains 81% of the total C3 together with most plasma β-globulins. Chromatography of this fraction on Whatman DE52, Sepharose 6B, and hydroxylapatite completes the purification of C3. A specific elution of C5, IgG, and IgA from hydroxylapatite is obtained with 2.0 M KCl before the elution of C3 with 100 mM K2HPO4 (pH 7.4). A constant ratio of 14,000 C3 CH50 units/mg C3 was observed throughout the purification, with quantitative immunoprecipitant and hemolytic titration assays indicating a 32% recovery of C3.
The reduction (0.02 M dithiothreitol, pH 8.6) and alkylation (0.042 M iodoacetamide) of C3 in 6.0 M guanidinium chloride (GuCl) results in the disassociation of two polypeptide chains: an α-chain and a β-chain with respective molecular weights of 120,000 ± 12,000 and 75,000 ± 7500.
Demonstration of a Non Osmotic Swelling and of a Three Step Mechanism During the Immune Lysis of Erythrocytes by Antibody and Complement
Authors: Valet G. , Opferkuch W. 
Published: January 2023

Abstract
E to EAC1-9 cell intermediates were sized electrically with a hydrodynamic focusing system which is a modified Coulter counter method that avoids the methodologically right skewed volume distribution curves of the original method. No changes in the volume distribution curves of the erythrocytes were observed up to the EAC1-8 state. On addition of C9, a dose-dependent part of the cells did swell and three steps could be distinguished in the lytic mechanism: 1) fixation of C9 to EAC1-8 cells, a process which proceeds also well at 0°C; 2) a temperature-dependent swelling of the erythrocytes to their maximal volume in an all or nothing fashion; and 3) lysis of the cell. The swelling of the erythrocytes to spheroids is of a non-osmotic nature because it occurs also in highly concentrated 36% albumin solutions where the colloid osmotic forces of the intracellular protein are balanced on a molar basis. It persists into the ghost phase.
Human Platelet-Initiated Formation and Uptake of the C5-9 Complex of Human Complement
Authors: Zimmerman T. S. , Kolb W. P. 
Published: January 2023

Abstract
We have studied the interaction of radiolabeled complement components with normal human platelets, platelets from a patient with paroxysmal nocturnal hemoglobinuria, and rabbit platelets in the absence of known complement activators or in the presence of cobra venom factor (CVF). When unwashed platelets in platelet rich plasma, or washed platelets suspended in serum or autologous plasma, were incubated for 30 min, C3 and terminal components (C5, C8, and C9) were found to bind to them. The terminal components were shown to be bound as the C5–9 complex, rather than as individual proteins, by eluting them from the platelet membrane and examining their behavior on ultracentrifugation. They co-sedimented at a rate characteristic of the stable C5–9 complex (22S). The complex so formed did not differ by ultracentrifugational criteria from that binding to rabbit platelets after CVF activation of complement. Although C3 was not included in the complex, it did not appear to be bound by nonspecific absorption.
Normal Mouse Serum Immunosuppressive Activity: Action on Adherent Cells
Authors: Martineau Ronald S. , Johnson John S. 
Published: January 2023

Abstract
The immunosuppressive activity of normal mouse serum (NMS) was evaluated by enumeration of primary in vitro plaque-forming cell response produced by normal spleen cell suspensions in response to sheep erythrocytes. The site of action of the inhibitor(s) was shown to be at the level of adherent cells since incubation of this cell type with NMS could reproducibly inhibit responses, whereas, in appropriate experiments, incubation of nonadherent cells with NMS had no effect. Furthermore, addition to normal spleen cells of excess spleen-adherent cells, normal peritoneal adherent cells, or of 2-mercaptoethanol could abrogate the inhibitory ability of NMS. Addition of excess nonadherent cells under the same conditions had no influence on inhibition. NMS was also shown to decrease the number of cell clusters, hemolytic clusters, and the number of nucleated cells recovered upon culture termination. It is suggested that NMS, acting on the adherent cell may hinder cell-to-cell contact and interactions.
Rabbit Antiserum against Daudi-Cell Membrane Fractions Detects Cell Surface Antigens Present on Subpopulations of Human Lymphocytes
Authors: Carrel S. , Gross N. , Salvi S. 
Published: January 2023

Abstract
An antiserum was produced by immunization of rabbits with membrane preparations of a human lymphoblastoid B cell line, Daudi. After absorption with a human endometrial carcinoma cell line, this antiserum appeared to be specific for antigen(s) present on adult and fetal thymocytes as well as on tonsillar lymphocytes but absent, or present in very small amounts, on normal or phytohemagglutinin- (PHA) stimulated peripheral blood lymphocytes (PBL). When T and B cell-enriched fractions from tonsillar lymphocytes were tested with the anti-Daudi serum, the reactivity was equally distributed in each population. Among 13 human lymphoblastoid cell lines tested, reactivity was demonstrated on three out of four T cell lines, and on four out of nine B cell lines. The positive reacting B cell lines were derived from two African and two American Burkitt lymphomas. The antigen(s) described does not seem to be related either to human Ia-type antigens or to Epstein-Barr virus-associated antigens because these antigens are not present on fetal or adult thymocytes. Reciprocal absorption experiments indicate that this anti-Daudi serum detects the same antigenic structures present on certain subpopulations of T and B lymphocytes.
Rous Sarcoma Virus-Transformed Avian Cells Express Four Different Cell Surface Antigens that Are Distinguishable by a Cell-Mediated Cytotoxicity-Blocking Test
Authors: Ignjatovic Jagodina , Rübsamen Helga , Hayami Masanori , Bauer Heinz 
Published: January 2023

Abstract
Japanese quails bearing avian sarcoma virus-induced tumors develop immune spleen cells that are cytotoxic in vitro against virally and chemically transformed cells, as well as against embryonic cells. The cell-mediated cytotoxicity can be blocked by soluble antigens extracted from in vitro cultured cells. The existence of partial as well as total blocking effects in tests with extracts from various transformed and untransformed virus-producing cells makes it possible to distinguish up to four different kinds of antigens expressed on sarcoma virus transformed cells: a) a subgroup-specific determinant of the virus-envelope glycoprotein gp85 (s-gp85) is expressed at the surface of productively infected, transformed as well as untransformed cells; b) a group-specific determinant of gp85 (g-gp85) that is only expressed on the surface of virus-transformed cells; c) embryonic antigens, also detectable on chemically transformed as well as on primary normal embryonic cells, and finally; d) a sarcoma virus transformation-specific antigen (TSSA) that is not a structural constituent of the virus.
Inhibition of Lymphoma Growth in the Spleen and Liver of Lethally Irradiated Mice
Authors: Iorio Anna , Campanile Franca , Neri Mariella , Spreafico Federico , Goldin Abraham , Bonmassar Enzo 
Published: January 2023

Abstract
The growth of murine lymphomas carrying the H-2d (LSTRA, P388), the H-2k (6C3HED), and the H-2a (LAF-17) haplotypes was studied in spleen and liver of lethally irradiated (850 to 1000 R) compatible or allogeneic mice, with the 125I-5-iodo-2′-deoxy-uridine uptake method. According to the genetic pattern of the Hh (hemopoietic-histocompatibility) system, recipient hosts were either susceptible or resistant to bone marrow graft carrying the same haplotypes as those of the lymphomas studied. The results showed that the tumor cell growth was impaired in the spleen of irradiated Hh-incompatible resistant hosts (e.g., P388 into B10, B10.BR and CBA), suggesting that lymphoma and bone marrow cells could share common Hh antigens. However, inhibition of lymphoma growth occurred also in the spleen of irradiated Hh-susceptible mice, either Hh-compatible (e.g., P388 into B10.D2; 6C3HED into AKR or CBA) or Hh-incompatible, but genetically unable to respond against bone marrow cells (e.g., LSTRA or P388 into C3H, or 6C3HED into BALB/c or SJL). In almost all cases growth inhibition was absent or weak in the liver. These results suggest that lymphoma cells could express antigens not detectable on normal bone marrow cells, capable of eliciting radioresistant inhibition of tumors (RIT) predominantly in the spleen of mice susceptible to marrow graft of the same genetic origin as that of the lymphoma tested. At the present time no direct data are available to determine whether natural cytotoxicity would play a role in RIT responses.
Binding and Activation of Human C1 by Immune Complexes Effect of Inhibitors
Authors: Arlaud G. J. , Sim R. B. , Reboul A. , Colomb M. G. 
Published: January 2023

Abstract
Human serum (pH 7.0) was incubated for 30 min at 0°C with ovalbumin-IgG anti-ovalbumin complexes in the presence of 50 µg/ml soybean trypsin inhibitor. After centrifugation and three washes at 0°C in a buffer containing 5 mM CaCl2 and 40 µg/ml STI (pH 7.0), C1̄r and C1̄s were resolubilized. From the C1̄s esterase activity and the SDS-polyacrylamide gel electrophoresis pattern, extracted C1̄r and C1̄s were found to be 75% activted. Complete activation was obtained by incubation for 30 min at 30°C before extraction.
Extraction of C1q, C1r and C1s in the presence of calcium. At pH 7.5, C1̄r and C1̄s were both readily extracted by increasing relative salt concentrations above 0.15. In contrast, C1q extraction started at RSC = 0.30 and increased more slowly.
C1̄r extraction paralleled C1̄s extraction as a function of pH, with a minimum at pH 7.0 and maxima at extreme pH values.
C1s Bound in Macromolecular C1 Exists in Equilibrium with C1s Free in Serum
Authors: Bartholomew R. M. , Esser A. F. 
Published: January 2023

Abstract
We have established the existence of an equilibrium between free C1s and C1s bound in macromolecular C1 in human serum. Untreated human sera were incubated for 35 hours at 4°C with 125I-C1s to allow the exchange between free and bound C1s to reach equilibrium. The C1 complex thus labeled was separated from most of the serum proteins and from excess 125I-C1s by centrifugation in linear 10–30% sucrose gadients. 125I-C1s became incorporated into macromolecular C1, as demonstrated by specific cleavage of all the labeled C1s to C1s̄ after incubation with known activators of the classical pathway of complement. Thus, C1 fractions containing 125I-C1s can be used directly and conveniently to assay C1 activation.
Incubating for more than 35 hours at 4°C neither increased nor decreased the amount of 125I-C1s in serum C1. Furthermore, excess 125I-C1s remained in the free protein pool of samples incubated more than 35 hours and entered C1 upon incubation with additional fresh serum.
Ss, The Murine Homologue of C4
Authors: Carroll Michael C. , Capra J. Donald 
Published: January 2023

Abstract
Serum substance (Ss), a serum protein, is known to be linked to the major histocompatibility locus of the mouse. Until recently the function of Ss was unknown but several lines of evidence, i.e. serologic, functional, and structural suggest Ss is murine C4.
The Ss protein has been isolated in pure form from murine ascites fluid and has been shown to have functional C4 activity. Purification was monitored by antigenic reactivity with a specific antiserum to Ss as well as with a hemolytic assay using genetically C4-deficient guinea pig serum.
Interactions Between Complement Proteins and Cell Membranes: Reduction in Membrane Fluidity Due to the Perturbation of the Lipid Bilayer by the Terminal Complex
Authors: Dahl Charles E. , Levine R. Paul 
Published: January 2023

Abstract
We have used 5, 12, and 16-nitroxyl stearic acid (5, 12, and 16-NSA) to spin label erythrocytes in order to investigate complement-induced changes in the organization of lipid bilayers. These changes are characterized by measurements of the hyperfine coupling, 2T11, a sensitive indicator of the motional freedom of the spin label and hence a measure of membrane fluidity. When 5, 12, or 16-NSA-labeled E or EA are lysed in hypotonic solution the value of 2T11 decreases indicating an increase in the fluidity of the bilayer. Upon resealing the lysed E or EA in the presence of Mg2+, 2T11 returns to its normal value. The fluidity of EAC ghosts, as measured by 2T11 is comparable to that of hypotonically lysed E or EA. When EAC are resealed in Mg2+ there is a significant decrease in membrane fluidity, for 2T11 increases to values greater than those obtained for resealed ghosts of E and EA.
Dependence of Complement Rosettes on a Nonenzymatic and an Enzymatic Step
Authors: Dierich M. P. , Landen B. 
Published: January 2023

Abstract
Rosette formation between typical EAC14oxy23 (human complement components; 1.2 hemolytically active C2 sites and 1 × 104 C3 molecules) and Raji cells can be reduced by 20 to 30%, of 0.5 mM diisopropylfluorophosphate (DFP) are present during the rosette assay. Reduction of rosette formation is only slightly less pronounced, if EAC14oxy23 are pretreated for 10 min at 23°C with 0.5 mM DFP. To elucidate the possible contribution of the C42Ѕ enzyme to the formation of rosettes, EAC1423 were prepared with nonoxidized C2. These EAC1423 were kept at 37°C for 30 min to decay the C2 and to obtain EAC143. Such cells formed about 10 to 15% rosettes. By treating the EAC143 with increasing amounts of oxidized C2 to form EAC14oxy23, rosette formation was increased up to 40%. This C2 dependent increase in rosette formation could be suppressed by DFP or by performing the rosette assay at 4°C.
The Morphology, Lifetime, and Pore Size of Complement Lesions on Erythrocyte Membranes
Authors: Esser A. F. , Halverson C. A. , Müller-Eberhard H. J. 
Published: January 2023

Abstract
The action of complement on sensitized erythrocytes (EA) results in release of hemoglobin (Hb) with concomitant formation of cell ghosts (EAC · gh). Prior cross-linking of EA with 0.025% glutaraldehyde (EA · X) prevents release of Hb upon incubation with C but not of trapped ions such as 86Rb indicating a limiting pore size of the lesion. The mechanism or entity that allows Hb release from EA, however, remains only transiently functional since EAC · gh reseal again. Using a simple sucrose-step-gradient centrifugation assay we found that more than 80% of EAC·gh are impermeable to molecules of the size of sucrose. In contrast, resealed ghosts, prepared from EA by hypotonic lysis and subsequent incubation with isotonic buffer (EA · gh), that have been cross-linked (EA · gh · X) remain permeable after incubation with complement (EA · gh · X · C). The successful introduction of C dependent pores into EA · gh · X depends on the amount of cross-linking.