bluuebunny/crossref_metadata_2025_split huggingface dataset:
C3b Inactivator: The Effect on Cell Bound C3b and a Simplified Functional Assay
Authors: Gaither Thelma A. , Gadek James , Frank Michael 
Published: January 2023

Abstract
The activity of C3b inactivator on the cellular intermediate site EAC43b was compared in three test systems (a functional hemolytic assay, an immune adherence assay, and a functional radioimmunoassay). 125I-C3 was incubated with EAC142 to form EAC1423*. C1 was removed with EDTA and C2 was allowed to decay at 37°C C/1 hr. When this intermediate was incubated with whole human serum or with partially purified C3b inactivator, there was a rapid loss of hemolytic C3 activity but very little specific removal of radioactive C3. A two-step assay was devised in which dilutions of normal human serum in low ionic strength buffer at pH 6.0 (.0375 µ dextrose-Veronal buffered saline, with 0.01 M EDTA, EDTA-VBS) were added EAC43b*. On exposure to trypsin (2.5 µg/ml) in .060 µ EDTADVBS for ten min at 30°C, radioactive C3 was released from the intermediate. This release of radioactivity correlated with the loss in hemolytic activity on exposure of EAC43b to C3b inactivator alone.
The Size of the Lesion Induced by the Alternative Complement Pathway on Human Erythrocyte Membranes
Authors: Giavedoni Elda B. , Dalmasso Agustin P. 
Published: January 2023

Abstract
By using a direct approach we have demonstrated previously that the classical C pathway produces on sheep erythrocyte membranes functional lesions of about 4 nm diameter. We have now investigated the size of the lesions induced on human erythrocyte membranes by activation of the alternative C pathway. Human red cells were treated with 2-aminoethylisothiouronium bromide (AET) to increase their reactivity with C. They were then lysed hypotonically in the presence of radiolabelled marker molecules of different size which were incorporated into the membranes ghosts during resealing. The membranes were finally treated with human serum together with inulin particles to activate the alternative pathway. This resulted in identical % release of 3H-sucrose from membrane ghosts and of hemoglobin from AET-treated intact erythrocytes. No release of 125I-ovalbumin or 125I-BSA was obtained from membrane ghosts. The release of soluble 3H-inulin was slightly slower and that of 125I-RNase markedly slower than that of 3H-sucrose.
The Role of Complement in Host Defense Against Bacteremia
Authors: Hosea Stephen W. , Frank Michael M. 
Published: January 2023

Abstract
In order to further study the role of complement in host defense, a model of pneumococcal bacteremia was developed in guinea pigs and mice. Type 4 pneumococci grown overnight in trypticase soy broth were injected intravenously, and clearance rates and organ distribution were studied by colony counts and 59Fe labeling of bacteria. C4-deficient (C4D) and normal NIH guinea pigs (GP) had similar patterns of rapid clearance. This was associated with activation of approximately 20,000 C3 molecules per bacterium. However, cobra venom factor- (CVF)treated animals had significantly delayed clearance of bacteria which was followed by overwhelming sepsis and death. Immunization produced enhanced clearance in normal GP but not in C4D animals, suggesting the requirement for an intact classical complement pathway for efficient immune clearance. Actively immunized CVF animals continued to exhibit delayed clearance and subsequent death.
Sequestration of bacteria occurred in the liver, spleen, and lung in the normal animal.
Mechanism of Endotoxin-Initiated Complement-Dependent Platelet Lysis
Authors: Morrison David C. , Oades Zenaida G. 
Published: January 2023

Abstract
We demonstrated earlier that bacterial endotoxins (lipopolysaccharides, LPS) have the capacity to activate both pathways of complement, with the polysaccharide portion of the molecule activating the alternative pathway and the lipid A region being responsible for classical pathway activation (Morrison, D. C. and Kline, L. F., 1977, J. Immunol. 118:362). We further showed that only preparations of LPS which initiate alternative pathway activation are capable of LPS-initiated complement-dependent rabbit platelet lytic responses. (Morrison, D. C. et al., 1976, Fed. Proc., 35:516).
Although the lipid A region of the LPS molecule is, itself, incapable of initiating lysis, our current experiments provide strong evidence that it does, in fact, play a critical role in the rabbit platelet response to LPS. Treatment of LPS with mild alkali (using conditions known to enhance binding of LPS to both erythrocytes and lymphocytes) significantly enhanced the extent of the complement-mediated platelet lysis.
C3bINA and its Macromolecular Weight Co-factor; Purification and Characterization
Authors: Nagasawa Shigeharu , Stroud Robert M. 
Published: January 2023

Abstract
The complement system is proteolytically modulated by the C3bINA-C4bINA system which is generally believed to cleave C3b into two fragments, C3c and C3d. However, little is known as to the exact mechanism of the proteolytic action of C3bINA on C3b and C4b. Recently, we documented the requirement of a macromolecular weight co-factor for the proteolytic function of C3bINA (Immunochemistry, in press). On the other hand, it was recently reported that β1H plays a role also as a co-factor for the proteolytic activity of C3bINA.
In the present study, we have purified the macromolecular weight co-factor and characterized it as a new serum protein. Also, we have highly purified the C3bINA by affinity chromatography with C3b-Sepharose, in order to study the cleavage mechanisms.
Purification and characterization of the macromolecular weight co-factor.
Analysis of the Peptide Maps of Human C2 and Factor B: Evidence for Structural Homology and Common Ancestry
Authors: Ngan Bo-Yee , Minta J. O. 
Published: January 2023

Abstract
C2 and Factor B are heat-labile β-globulins in normal human serum and are the precursors of the C3 and C5 convertase enzymes of the classical and alternative complement pathways, respectively. Genes controlling C2-deficiency and polymorphism and Factor B polymorphism have been linked to the HLA locus. In this study, proteolysis of C2 and Factor B have been compared by a peptide mapping technique on SDS polyacrylamide gel electrophoresis. C2 and Factor B were purified from the 20% Na2SO4 supernatant of human plasma by sequential column chromatography and by preparative gel electrophoresis in barbital-glycine buffer, pH 8.8. The highly purified C2 and Factor B sedimented at 5.2S and 5.0S, respectively, and were hemolytically and esterolytically active. The m.w. for C2 and Factor B estimated by SDS polyacrylamide gel electrophoresis in the presence or absence of reducing agents were 117,000 and 93,000 daltons, respectively, suggesting that each protein is comprised of a single polypeptide chain.
The C2 Polymorphism: Its Genetics and Presentation of Typing Technique Modifications
Authors: Olaisen B. , Teisberg P. , Thorsby E. , Gedde-Dahl T. 
Published: January 2023

Abstract
The originally described C2 typing technique has been modified to allow typing on ordinary electrofocusing equipment, without the use of specific C2-deficient serum. The modifications include prolonged electrofocusing time, iodine treatment of gels after focusing, and the use of low concentration normal human complement as “C2-lacking complement.”
In a Norwegian population sample C2 gene frequencies were: C21: = 0.97, C22: = 0.03, these frequencies fit well with those reported in other Caucasian populations.
C2-linkage relations and haplotype associations have been examined in an extensive Norwegian family material. No recombinations were found in 22 informative C2/HLA-B meioses and the rare C22 allele was accompanied by the HLA-Bw15 allele in 6 out of 7 instances. Our data therefore confirm the linkage of C2 to the HLA region loci, and we conclude that C2 is situated in close proximity to the HLA-B locus.
Influence of Lymphokine on Complement Components Synthesis by Guinea Pig Spleen Cells In Vitro
Authors: Peltier A. P. , Cambier A. 
Published: January 2023

Abstract
A large part of complement components are synthetized by cells of the macrophage-monocyte type which are under narrow control by lymphokines. Preliminary results obtained in our laboratory have shown that addition of phytohemagglutinin M to a culture of whole normal guinea pig spleen cells decreased the amount of C2 detectable in the culture supernatant at the same time where it strongly stimulated lymphocyte proliferation, as shown by a high rate of cellular 3H-thymidine incorporation. One possible explanation for this phenomenon would be the inhibition by some lymphokine of C2 synthesis by macrophages.
In order to substantiate this hypothesis, a two step experiment was designed. Whole normal guinea pig spleen cells (0.5 ml of 20 × 106/ml suspension) were first cultivated for 24 hours in the presence of an optimal 50 µg dose of insoluble concanavalin A. The supernatant obtained was assayed for its lymphokine activity by a classical Macrophage Inhibition Test.
A Specific Indicator for the C3b Receptor on Mouse B Cells and Altered States of C3b Reactivity
Authors: Ranken Raymond , Linscott William D. 
Published: January 2023

Abstract
Mouse B lymphocytes have separate surface receptors for mouse C3b and C3d, but study of their function has been hampered by a lack of indicator particles completely specific for each receptor type.
We report here that mouse spleen lymphocytes will bind to guinea pig (GP) C3b but not to GP C3d, so any possible contamination of the indicator cells with C3d should be of little consequence. There was no binding to GP C4. Indicator cells were prepared from EAC142 GP and purified GP C3. They were maximally reactive in I-A, unreactive with bovine conglutinin, and rosetted with about 27% of mouse and GP spleen cells. When these EAC43b were incubated for 40 min at 0°C in EDTA with heated GP serum, there was little or no change in their I-A activity, but they lost completely the ability to rosette with mouse (but not GP) lymphocytes; their C3 hemolytic activity was markedly reduced; and they gained the capacity to be agglutinated by bovine conglutinin.
On the Perturbation of Phospholipid Bilayers by Complement: The Use of Inside-Out Vesicles from Complement-Lysed Erythrocytes for the Demonstration of Perturbating Peptide Chains
Authors: Rauterberg E. W. 
Published: January 2023

Abstract
It has been postulated by different groups that late complement components may partly insert into the phospholipid bilayer of complement lysed erythrocytes and form a trans-membrane channel.
The present report examines whether complement component antigens can be detected at the inner surface of complement lysed membranes by the use of inside-out vesicles. Insideout and right-side-out vesicles from osmotically or complement lysed sensitized sheep erythrocytes (EA or EAC1-9) were obtained by an incubation in a low ionic strength phosphate buffer, pH 8.0, followed by a gentle homogenization to liberate the entrapped vesicles.
Inside-out and right-side-out vesicles were separated on linear gradients of Dextran T 110 by centrifugation to equilibrium. Inside-out vesicles from EAC1-9 (IO-EAC) as well as those from osmotically lysed sensitized sheep erythrocytes (IO-EA) revealed both a very low binding of 3H-Ouabain in comparison to the respective right-side-out vesicles (RO-EAC and RO-EA). The four types of vesicles were radioiodinated by lactoperoxidase and glucose oxidase.
Structural Variability in Human C4: Methodological and Genetic Data
Authors: Teisberg P. , Olaisen B. , Gedde-Dahl T. , Thorsby E. 
Published: January 2023

Abstract
We have previously demonstrated a genetic polymorphism of human C4. Modification of the methods employed in the separation and detection of C4 proteins has shown that further molecular variability exists in C4. By employing prolonged high voltage electrophoresis in agarose and a sensitive hemolytic detection system, three common C4 alleles and one less common have been detected. The following gene frequencies have been found in the Norwegian population: C4F: 0.46, C4F1: 0.20, C4S: 0.32, C4M: 0.02.
In 165 informative meioses not a single recombinant has been observed between C4 and HLA-B. In three known cross-over events between HLA-A and B, C4 in each instance follows B. The short map distance between C4 and HLA-B is further substantiated by haplotype association data. All 12 HLA-B8 chromosomes carry C4S. In seven out of eight instances HLA-B7 follows C4F1.
In 53 informative meioses no cross-over event has been observed between C4 and Bf (locus for factor B).
Hydrolytic Activation of the Fifth Component of Complement (C5) by C3 Convertases Depends on its Binding to Surface-fixed C3b; Specific Interference with Binding, by Properdin, Factor B, or Propamidine, Leads to Inhibition of C5 Cleavage and Utilization
Authors: Vogt W. , Schmidt G. 
Published: January 2023

Abstract
The C3 convertases of the classical and alternative pathways, and C3bBb (P) are capable of cleaving C5 only in the presence of C3b fixed to a solid surface (S-C3b) immediately subsequent to its release at that surface (e.g., on red cells, agarose, zymosan). The fact that fluid-phase and to a lesser degree soluble , attack C5 in the presence of S-C3b in EDTA medium, indicates that S-C3b interacts with and modulates the substrate, C5, rather than the convertase. In fact, reversible binding occurs between S-C3b and C5. Soluble C3b shows no indication of C5 binding, and does not support C5 cleavage by or C3b Bb. Cobra venom factor (CVF) which supports a B-dependent C5-cleaving enzyme, CVFBb, combines with C5 even in solution. While CVFBb cleaves C5 efficiently only when substrate (C5) and enzyme (Bb fragment) are bound to the same CVF molecule (free CVF added to a mixture of CVFBb and C5 is inhibitory), S-C3b has to be free of other ligands in order to function as a C5-binding site.
Modulation of Generation of the Amplification Convertase C3b,Bb by Heparin
Authors: Weiler J. M. , Yurt R. W. , Austen K. F. 
Published: January 2023

Abstract
Commercial heparin, a degraded mixture of hog glycosoaminoglycans, inhibits generation of the amplification convertase, C3b, Bb, on a cellular intermediate or in the fluid phase. Heparin is most active in inhibiting convertase generation on cellular intermediates formed with the lowest C3 input and developed with the highest B concentration, suggesting that the point of heparin action is the receptor site for B on C3b. Inhibition is observed also when C3b,Bb generation takes place on cellular intermediates in the presence of P or C3NeF, which yield stabilized forms of the convertase. This inhibitory action of heparin is not due to chelation of magnesium. Fifty times the concentration of heparin required to inhibit convertase generation does not accelerate the decay of the unstabilized or the C3NeF-stabilized convertases and has only a modest effect on the P-stabilized convertase. These studies indicate that in addition to the previously reported sites of heparin inhibition on classical pathway function noted by others, heparin acts to prevent effective interaction of C3b and B, most likely by a reversible action on C3b.
Activation of the Alternative Pathway by Pneumococcal Cell Wall Teichoic Acid
Authors: Winkelstein Jerry A. , Tomasz Alexander 
Published: January 2023

Abstract
Previous studies on the interaction of pneumococci and the alternative pathway have shown that the cell wall, rather than the cell membrane or capsule, plays a major role in the activation of the alternative pathway. The present study was performed in order to identify the biochemical component of the pneumococcal cell wall responsible for activating the alternative pathway.
Teichoic acids were extracted from purified pneumococcal cell walls by three different procedures (0.05 M periodate at 37°C; 100% formamide at 170°C; 5% TCA at 4°C). In each case the teichoic acids were able to consume C3 in C4-deficient guinea pig serum (C4D GPS) at concentrations as low as 3 to 10 µg/ml. In contrast, the residual cell walls, which contained the peptidoglycan, lost their activity in proportion to the amount of teichoic acid that had been extracted. Notably, cell walls extracted with periodate lost over 98% of their teichoic acid and the residual cell wall peptidoglycan was unable to consume C3 in C4D GPS at concentrations as high as 1 mg/ml.
Biochemical Relationship between Murine Immune Interferon and a Killer Cell Helper Factor
Authors: Simon Philip L. , Farrar John J. , Kind Phyllis D. 
Published: January 2023

Abstract
Concanavalin A and alloantigen-stimulated mouse spleen cells release into the supernatant at least two distinct antigen-nonspecific factors that enhance the generation of cytotoxic cells in vitro. As previously reported, analysis of the supernatant by ammonium sulfate fractionation, gel filtration, hydroxylapatite chromatography, and hydrophobic chromatography showed one of the two killer cell helper factors (KHF) to be associated with thymocyte mitogenic factor. This report demonstrates the second KHF to be separable from thymocyte mitogenic factor but inseparable from type II (immune) interferon. In addition, this KHF exhibits the same sensitivity to exposure to pH-2 buffer as does immune interferon. The KHF activity of an unfractionated supernatant, which is greater than that of either the TMF-associated or interferon-associated KHF alone, is the result of the additive activities of the two independently acting helper factors.
Antigen-Binding T Cells: Dose Response and Kinetic Studies on the Development of Different Subsets
Authors: Eardley Diane D. , Shen Fung W. , Cone Robert E. , Gershon Richard K. 
Published: January 2023

Abstract
We have described a number of the parameters involved in the in vitro induction of specific SRBC-binding T cells (T rosette-forming cells, T-RFC). Although T-RFC precursors pass through nylon, most of the induced cells do not; nor do detectable numbers of Ly 1+2, 3- cells bind antigen with sufficient stability to form rosettes. The ratio of Ly 2,3:Ly 1,2,3 T-RFC varies with time after immunization and with the dose of antigen used for stimulation. Relatively high or low doses of antigen selectively induce Ly 1,2,3 T-RFC. Ly 2,3 T-RFC, when they appear, follow Ly 1,2,3 T-RFC. Pretreatment of T cells with anti-Ly sera before RFC induction prevents formation by Ly 2+ T-RFC.
Since anti-Ly 1 treatment blocks RFC formation and since Ly 1,2,3 T-RFC always precede the appearance of Ly 2,3, T-RFC, our results suggest that some Ly 1+ cells (Ly 123 at least, but perhaps also Ly 1) may act as inducers, precursors, and/or amplifiers for Ly 2,3 RFC as they appear to do for Ly 2,3 suppressor and killer cells. Thus, our results confirm and extend the observed similarities between T-RFC and other Ly 2+ cells such as killer and suppressor cells as well as their differences from Ly 1+ helper cells.
Characterization of an Antiserum Specific for the Fabα Fragment
Authors: Doe William F. , Spiegelberg Hans L. 
Published: January 2023

Abstract
An antiserum to the Fabα fragment of human IgA was prepared by injecting κ- and λ-type IgA1 myeloma protein Fab fragments in complete Freund's adjuvant into a goat. After appropriate absorptions, the antiserum reacted specifically with Fabα fragments, normal IgA, and κ- and λ-type IgA1 and IgA2 myeloma proteins. This antiserum contained predominantly antibodies to determinants shared by different IgA myeloma proteins and expressed on isolated α chains. These determinants were presumably located on the first constant domain of the α chain (Fd fragment). When incorporated into agarose, the anti-Fabα antiserum is a potentially valuable reagent for screening human sera for α-heavy chain disease proteins by an immunoelectrophoretic method of immuno-selection.
The Purification and Quantitation of Helper T Cell-Replacing Factors Secreted by Murine Spleen Cells Activated by Concanavalin A
Authors: Watson James , Aarden Lucien A. , Lefkovits Ivan 
Published: January 2023

Abstract
A microculture assay with low numbers of athymic (nude) spleen cells has been used to quantitate the helper T cell-replacing activity secreted by concanavalin A-treated spleen cells. This quantitation allows an estimate of the recovery of biologic activity during concentration from culture supernatants by salt precipitation, and purification by gel filtration, ion exchange chromatography, and isoelectric focusing. The T cell-replacing activity is found in protein of 30 to 40,000 daltons size as estimated by gel filtration, but shows heterogeneity in electric charge. The activity is active at concentrations of less than 10-9 M, and is strictly antigen dependent in its mode of action.
The Functional Size of the Primary Complement Lesion in Resealed Erythrocyte Membrane Ghosts
Authors: Giavedoni Elda B. , Chow Yeh Mei , Dalmasso Agustin P. 
Published: January 2023

Abstract
We compared the susceptibility to complement (C) lysis of resealed sheep erythrocyte membrane ghosts (M) with that of intact erythrocytes (E). E were lysed hypotonically in the presence of radiolabeled marker molecules that were entrapped in the M during resealing. C-induced lysis was measured by the amounts of 3H-sucrose and hemoglobin released from antibody (A)-treated M (MA) and E (EA), respectively. The degree of lysis produced by different concentrations of guinea pig serum was identical for both systems. Treatment with C8 and C9 resulted in identical levels of lysis of MAC1-7 and EAC1-7; in addition, similar binding of radiolabeled C8 by MAC1-7 and EAC1-7 was obtained. These results demonstrate that the reactivity of M with A and C is similar to that of intact E.
To determine the effective pore size of the primary C lesion, radiolabeled molecules of different size were entrapped in the M, and their release by A and C as a function of time or C concentration was investigated. An excess of guinea pig, human, or rabbit serum produced complete release of 3H-sucrose and 3H-inulin at the end of 60 min of incubation at 37°C, but the release of 125I-ribonuclease (RNase) proceeded at a slower rate. The rates of release were directly related to the size of the marker molecules and the concentrations of C used. With 125I-ovalbumin and larger molecules (hemoglobin, 125I-bovine serum albumin, 125I-urease, and 125I-thyroglobulin) the release was of low level and similar for all molecules. The release in controls with heat-inactivated (56°C, 30 min) guinea pig and human serum or C6-deficient rabbit serum was less than 10% for all markers after 60 min of incubation at 37°C. The patterns of release of marker molecules from MAC1-7 reacted with C8 and C9 were similar to those of EA treated with serum as source of C. However, the differences in rate of release of the various markers were more pronounced. Incubation of MAC1-7 alone resulted in a 10 to 12% release of all markers after 60 min at 37°C, and incorporation of C8 produced an additional 10% increase in release. Because RNase and smaller molecules can readily diffuse across C-treated M, we conclude that the size of the primary C lesion has a minimal diameter of 40 Å. It is also possible that resealing of larger primary C lesions occurs rapidly and thus markedly reduces the egress of large molecules from the lysing M.