bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of C1r by Proteolytic Cleavage
Authors: Ziccardi Robert J. , Cooper Neil R. 
Published: December 2022

Abstract
C1r was unable to cleave and activate proenzyme C1s unless first incubated at 37°C in the absence of calcium before the addition of C1s. The acquisition of ability to activate C1s was associated with, and paralleled by, cleavage of each of the two noncovalently bonded 95,000 dalton chains of the molecule into disulfide linked subunits of 60,000 and 35,000 daltons, respectively. Thus, C1r is converted from an inactive form into an enzyme, C able to cleave and activate C1s by proteolytic cleavage in marked analogy to the activation of several other complement enzymes. Trypsin was also found to cleave C1r but at a different site, and its action did not lead to C1r activation.
C1r activation was inhibited by calcium, polyanethol sulfonate, C1 inactivator, and DFP but not by a battery of other protease inhibitors. C1 inactivator inhibited C by forming a complex with C1r via sites located on the light chain of the molecule. In other studies, cleavage of C1r was not accelerated by the addition of C or C1s.
C1r and C were found to have the same m.w., sedimentation coefficient, and diffusion coefficients. They differed, however, in charge with C1r migrating as a β-globulin and C as a γ globulin on electrophoresis in agarose. The amino acid composition of C1r and of each of the two polypeptide chains of C was determined. Both chains contained carbohydrate.
Proteolytic cleavage of the C1r molecule was found to occur on addition of aggregated IgG to a mixture of C1q, C1r, and C1s in the presence of calcium. Neither C1q, C1s nor aggregated IgG alone, nor C nor C induced C1r cleavage. Liquoid, an inhibitor of C1 activation, inhibited C1r cleavage. Thus, proteolytic cleavage of C1r appears to be a biologically meaningful event occurring during the activation of C1.
The Role of Lymphotoxin in Target Cell Destruction Induced by Mitogen-Activated Human Lymphocytes in Vitro
Authors: Kramer Sandra L. , Granger Gale A. 
Published: December 2022

Abstract
The in vitro destruction of phytohemagglutinin (PHA) coated β L cells by non-immune human lymphocytes was resolved into two distinct phases—lymphocyte dependent and lymphocyte independent. The initial or lymphocyte-dependent phase occurred within the first 2 hr and proceeded equally well at 34 and 37°C. The amount of lymphotoxin (LT) secreted by PHA-activated human lymphocytes in vitro to PHA stimulation was the same at 34 and 37°C. Antiserum and complement inactivation of the aggressor lymphocytes at various intervals revealed that target cell lysis was lymphocyte independent. However, the latter phase was temperature dependent, i.e., proceeding at the permissive temperature of 37°C, but inhibited at the restrictive temperature of 34°C. Further experiments revealed that LT-induced destruction had the same temperature sensitivity as target cell cytolysis occurring during the lymphocyte-independent step. Trypsin treatment of target cells during an early period of the lymphocyte-independent phase protected the target cell from subsequent death, indicating the aggressor lymphocyte has deposited a cytotoxic effector material on its surface. These results suggest the lymphocyte-dependent stage involves the processes required for the induction of LT synthesis and secretion. The actual cytolysis occurring during the lymphocyte-independent stage may be caused by LT or LT-like material(s) deposited on the target cell surface by the mitogen-activated human lymphocyte.
Isolation of Stable and Unstable (“Suppressed”) β2-Microglobulin-Deficient Clones from a Lymphoid Cell Line
Authors: Pious Donald , Soderland Carl , Weagant Stephen , Poulik Dave 
Published: December 2022

Summary
After selection with anti-β2m and C against a human lymphoid line, about 10% of surviving clones manifested decreased cytotoxic sensitivity to anti-β2m (“suppression”) which gradually reverted to normal after 35 to 55 cell doublings. Antiserum alone induced suppression. Exposure of suppressed clones to DMSO substantially reversed suppression. One clone, surviving selection, had a stable decrease in anti-β2m sensitivity; it possibly represents a β2m mutation.
Immune Serum-Mediated Cytotoxicity Against Trypanosoma Rhodesiense
Authors: Diggs Carter , Flemmings Barbara , Dillon James , Snodgrass Ralph , Campbell Gary , Esser Klaus 
Published: December 2022

Abstract
The metabolic integrity of Trypanosoma rhodesiense can be assessed in vitro by the extent of incorporation of radiolabeled leucine into trichloroacetic acid precipitable material or into material retained after filtration on a glass fiber filter. Incorporation is an approximately linear function of time, and the rate of incorporation is linearly dependent on cell concentration in the presence of normal rat serum. Incorporation is completely prevented if the organisms are reacted with fresh serum from animals immunized with gamma-irradiated parasites; the degree of inhibition is a function of the dose of immune serum used. This serum-mediated cytotoxic activity is abrogated by heating the serum, but can be fully restored by addition of fresh rat or guinea pig serum to the heated immune serum. The serum activity arises promptly after one to four immunizing doses of irradiated parasites, falls to lower levels by 1 month, but persists for at least 2 ½ months, and is unaffected by challenge with viable trypanosomes.
Synthesis of Gm Allotypes by Human Tonsillar Lymphocytes in Culture: Concordance with Serum Phenotype
Authors: Litwin Stephen D. , Hütteroth Thomas H. , Balaban Linda 
Published: December 2022

Abstract
Isolated human tonsillar lymphocytes were cultured with pokeweed mitogen, phytohemagglutinin, and without mitogen for 9 to 28 days. IgK, Gm(a) and Gm(f) were then quantitated in the cell suspensions. In cultures of cells derived from persons whose blood was heterozygous for IgGl allotype antigens Gm(a+f+), approximately equal amounts of Gm(a) and Gm(f) were found. In cultures of cells of Gma or Gmf homozygotes, there was complete concordance between the Gm allotype antigens produced by the cultures and the donor's serum phenotype—with no instance, either at zero time or at culture termination in which a Gm antigen was detected which was absent from the donor's serum. It was concluded that in vitro genetic allotype synthesis in tonsillar lymphocytes during short-term culture mirrored accurately in vivo Gm expression.
IgK and Gm antigen synthesis was highest in the flasks containing pokeweed mitogen although both phytohemagglutinin and no-mitogen control flasks showed, in certain experiments, proliferation and an increase in the Ig per viable cell. It was observed that no-mitogen flasks contained twice as much allotype antigen as did phytohemagglutinin flasks suggesting an inhibition of Ig synthesis associated with the mitogen. The tonsillar lymphocytes, under the experimental conditions employed, were shown by a radio-incorporation and immunoprecipitation technique to be synthesizing polyclonal Ig de novo, at the termination of the cultures.
The Defect in µ Heavy Chain Disease Protein GLI
Authors: Franklin Edward C. , Frangione Blas , Prelli Frances 
Published: December 2022

Summary
Amino acid sequence studies of µHCD protein GLI reveal the absence of the amino terminal 130 residues. The molecule starts at Ala 131 and contains Cys 140, normally involved in the H-L disulfide bridges. Except for the deletion and presumably an extra H-H disulfide bridge involving Cys 140, the remainder of the µ-chain appears normal.
Factors Influencing the Response of Mice to Type III Pneumococcal Polysaccharide
Authors: Warr Gregory W. 
Published: December 2022

Abstract
Sir: I would like to comment on a number of issues raised by your correspondents Baker and Prescott (1), in their letter entitled “The Basis for Conflicting Results Obtained in Studies on the Plaque-Forming Cell Response to Type III Pneumococcal Polysaccharide.”
Their argument can, I believe, be summarized in the following points.
Anti-lymphocyte serum (ALS)-induced enhancement of the response to Type III pneumococcal polysaccharide (SIII) has only been observed (2–4) by using indicator erythrocytes sensitized, by the chromic chloride method, with purified SIII (5), but not by using indicator erythrocytes sensitized with the filtrate from a culture of pneumococci (6–8) as described originally by Askonas et al. (9). This culture-filtrate method of sensitizing target erythrocytes detects primarily response to a contaminating antigen present in small amounts in the immunizing preparation of SIII, but present in large amounts in the culture filtrate.
Antibody-Dependent Cell-Mediated Cytotoxicity in Humans
Authors: Trinchieri Giorgio , De Marchi Mario 
Published: December 2022

Abstract
Different classes of protease inhibitors and substrates were tested for their effect on the ability of human lymphocytes to mediate antibody-dependent cytotoxicity (Ab CMC). All the inhibitors tested (serine esterase inhibitors, chloromethyl ketone derivatives of tosyl-amino acids, synthetic protease substrates), except for the naturally occurring protease inhibitors (derived from soybean, lima bean, and porcine pancreas), were able to suppress, or to reduce significantly, the cytotoxicity. In the absence of a direct demonstration of an esterase activity, sensitive to the action of the inhibitors in the effector lymphocytes, careful controls were used to restrict the possibility that some nonspecific effect of the drugs was being interpreted. Particularly, the dependence of the inhibition of cytotoxicity as an effect of drugs on membrane transport mechanisms or on energy metabolism was excluded. The similarity between results obtained with compounds of different chemical characteristics and different molecular mechanisms of action supports a specific effect of the inhibitor on cellular esterase(s) or possibly protease(s). The fully reversible inhibition obtained with serine esterase inhibitors suggests that the relevant enzymes are activated only after effector-target cell interaction; the irreversible effect of chloromethyl ketone derivatives, however, does not allow the participation of already activated enzymes to be excluded.
The results presented in this study on the probable role of cellular esterases, on cation requirement and on the sequence of biochemical steps in Ab CMC add a new element to the analogy between this cellular phenomenon and different types of cytotoxicity or other immunologically induced cellular reactions, suggesting that the biochemical mechanisms of cytotoxicity may partly reflect a common pattern of cellular response to external stimuli.
Characterization of T and B Antigen-Binding Cells for β-Galactosidase
Authors: Swain Susan , Modabber Farrokh , Coons Albert H. 
Published: December 2022

Abstract
The results reported in this paper demonstrate that the enumeration of cells binding β-galactosidase (Z) as an antigen, revealed by subsequent substrate hydrolysis, is an excellent method for the detection and study of antigen-binding cells (ZBC). The binding found is specific and is restricted to a small number of lymphocytes that bind a large number of Z molecules via surface receptors. Such ZBC were found at mean frequencies of 150 per 106 in the thymus and 200 to 300 per 106 in the spleen. The binding cells of both organs were heterogenous with individual ZBC binding from 105 to 106 molecules of enzyme as determined by substrate hydrolysis, although this might well be an overestimate of the number of actual receptors. The profiles for the frequency of ZBC binding different numbers of molecules were nearly identical for thymus and spleen, in contrast to descriptions of the binding of many other antigens. Receptors responsible for Z binding appear to be superficially located on the cell since they are trypsin-sensitive to a large extent and are not increased by fixation.
Age-Associated Involution of Cellular Immune Function
Authors: Pachciarz Judith A. , Teague Perry O. 
Published: December 2022

Abstract
Autoimmune-susceptible (A/J and C57BL/6J) and non-autoimmune-susceptible (DBA/1J) strains of mice were adult thymectomized (aTx). Groups of mice, treated by aTx, aTx and 330 rads (R), aTx and 650 R, and 330 R or 650 R only, were compared to normal age-matched control (normal and sham Tx) mice. T cell functions were then followed as measured by in vitro spleen cell responsiveness to the T cell mitogens phytohemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) in a long-term study. A decline in spleen cell responsiveness with natural aging up to 18 months of age was seen to PHA in all three strains and to SEB in A/J and C57BL/6J mice. Adult Tx alone was followed by an accelerated decline in spleen cell responsiveness to PHA and SEB in all three strains of mice. Irradiation combined with aTx-reduced spleen cell responsiveness to SEB in A/J and DBA/1J mice. Irradiation with or without aTx diminished the bone marrow stem cell pool as measured by exogenous colony-forming units, and the hematocrit of all three strains of mice. Thus, the natural decline in cellular immunity with aging was accelerated by aTx in both autoimmune-susceptible and non-autoimmune-susceptible strains of mice. These results emphasize that physiologic thymic function(s) must continue throughout life in order to maintain T cell function.
IgM Complex Receptors on Subpopulations of Murine Lymphocytes
Authors: Lamon E. W. , Andersson B. , Whitten H. D. , Hurst M. M. , Ghanta V. 
Published: December 2022

Abstract
Murine lymphocytes from spleen, lymph node, and thymus were examined for IgM complex receptors. Lymphocytes from all three organs were found to bind SRBC sensitized with IgM from various sources including: primary anti-SRBC serum, murine and rabbit anti-Escherichia coli LPS sera, and a murine IgM myeloma (MOPC 104E). Rosette formation by lymphocytes with IgM-sensitized SRBC was inhibited by soluble antigen-IgM complexes but not by IgM or antigen alone. Rosette formation was also inhibited by human IgM (Fc)5µ but not by Fab µ. Antiserum and complement treatment of the cells and subsequent recovery of the viable cells by trypsinization, filtration, and washing revealed the IgM rosette-forming cell (RFC) in the thymus to be a T cell. Spleen on the other hand was found to contain both B and T cells capable of binding IgM sensitized SRBC. Removal of both B and T cells from spleen cell suspensions eliminated all IgM RFC. The IgM complex receptor was found to be trypsin insensitive. Anti-Ig column fractionation enriched IgM RFC in spleen and lymph node suspensions passed through the columns, whereas cells bearing surface Ig, IgG complex receptors, and C3 receptors were retained in the columns.
Purification and Characterization of a Liver-Specific Antigen
Authors: Mihas Anastasios A. , Hirschowitz Basil I. , Saccomani Gaetano 
Published: December 2022

Abstract
A liver-specific antigen (F-antigen) previously demonstrated in saline extracts of BALB/c mouse liver by double immunodiffusion was isolated and characterized. The antigen was found widely distributed among mammals but absent from avian and frog liver extracts. In immunoelectrophoresis it had an electrophoretic mobility similar to that of serum β2-globulins, was relatively thermolabile, and was precipitated at 30 to 70% saturated ammonium sulfate concentration. Evidence was presented that this antigen is a protein or a moiety closely associated with protein. Gel-filtration on Sephadex G-200 revealed liver-specific antigenicity in the second peak. Ion-exchange chromatography on DEAE-Sephadex A-50 revealed four peaks of which only the third one exhibited liver-specific antigenicity. This active peak contained 11 polypeptides on SDS polyacrylamide gel electrophoresis. After electrophoresis on acrylamide gel in the absence of SDS, antigenic activity was detected on one fast-moving band. Extraction of the protein band followed by SDS gel electrophoresis showed one major component of m.w. 75,000 and two minor bands of m.w. 72,000 and 93,000, respectively.
Reaginic Antibody Formation in the Mouse
Authors: Takatsu Kiyoshi , Ishizaka Kimishige 
Published: December 2022

Abstract
Intravenous injections of urea-denatured ovalbumin (UD-OA) into OA-primed high responder mice suppressed the antibody response not only to the priming antigen but also to subsequent immunization with dinitrophenyl derivatives of OA (DNP-OA). The transfer of normal spleen cells or OA-primed spleen cells into UD-OA-treated animals did not restore the capacity of responding to DNP-OA to form anti-DNP IgE and IgG antibodies. The transfer of splenic T cell fraction from the UD-OA-treated animals into normal syngeneic mice diminished both IgE and IgG antibody responses of the recipients to DNP-OA. The B cell-rich fraction from the same donors failed to affect the anti-hapten antibody response and enhanced anti-carrier (OA) IgG antibody response of the recipients. It was also found that the transfer of T cell-rich fraction of OA-primed spleen cells failed to suppress antibody response of the recipients to DNP-OA. The results indicated that spleen cells of UD-OA-treated mice contained suppressor T cells which are distinct from helper cells. Suppressive activity of T cells in the UD-OA treated animals was specific for OA. The transfer of the T cell-rich fraction failed to suppress anti-DNP antibody response of the recipients to DNP-KLH.
Changes in C3 Metabolism during Protozoan Infection (Babesia Rodhaini) in Rats
Authors: Chapman William E. , Ward Peter A. 
Published: December 2022

Abstract
Metabolism of the third component of complement (C3) and IgG was measured in rats before and during infection with the hemosporidium agent Babesia rodhaina. In the course of infection, hypocomplementemia and immune complex nephritis developed. During babesial infection, in most animals the half-life of C3 fell sharply, as did serum levels of C3; the catabolic rate for C3 sharply increased, whereas the synthetic rate sharply decreased. In contrast, the catabolic rate for IgG remained unchanged. The alteration in the metabolism of C3 in the face of nonparallel changes in IgG metabolism suggests that abnormal glomerular filtration and increased vasopermeability cannot explain the findings. Babesial infection in the rat provides a useful model for the study of acquired C3 metabolic defects that have been observed in humans with immune complex diseases.
Effects of C-Reactive Protein on Platelet Function
Authors: Fiedel Barry A. , Gewurz Henry 
Published: December 2022

Abstract
C-reactive protein (CRP) is an acute phase reactant which shares numerous functional characteristics with the immunoglobulins. In the present study CRP was found to inhibit the aggregation of human platelets stimulated by either modified human immunoglobulin or thrombin. This effect did not involve chelation of calcium or cytotoxicity, and was overcome by larger amounts of the aggregating agents. CRP also inhibited the activation but not the activity of platelet factor 3 and the release of β-glucuronidase. Thus, CRP can inhibit multiple platelet reactivities. We suggest that this property of CRP may play an important role in the control of platelet responsiveness during reactions of inflammation, defense, and repair.
The Binding of Complement by Complexes Formed Between a Rabbit Antibody and Oligosaccharides of Increasing Size
Authors: Jaton Jean-Claude , Huser Hans , Riesen Walter F. , Schlessinger Joseph , Givol David 
Published: December 2022

Abstract
Immune complexes formed between a homogeneous rabbit antibody to type III pneumococcal polysaccharide and a series of oligosaccharides of varying size derived from it were prepared and tested for their ability to fix guinea pig hemolytic complement.
Antibody and either tetra-, hexa-, or octasaccharide formed only monomeric antibody-hapten complexes and did not show any complement binding. A dodecasaccharide and a 16-sugar residues oligomer formed dimer and trimer immune complexes. These complexes were also unable to fix complement. However, as the size of the sugar oligomers was increased to about 21 sugar residues per oligosaccharide molecule or more, the resulting complexes exhibited substantial complement binding, concomitant with the formation of antigen-antibody aggregates higher than trimers.
On the other hand, an independent study carried out with the same material suggested changes in the conformation of the Fc moiety in the antibody molecule upon addition of oligosaccharide ligands as small as a 16-residue unit. Since the resulting complexes hardly exhibited any complement binding, ligand-induced conformational changes in the Fc part of the antibody molecule appears to be an insufficient condition per se for triggering complement fixation.
The Significance of Varying SRBC/Lymphocyte Ratio in T Cell Rosette Formation
Authors: Chisholm Rex L. , Tubergen David G. 
Published: December 2022

Abstract
The incubation ratio of sheep red blood cells (SRBC) to lymphocytes is a critical factor in rosette formation, whereas the length of time SRBC and lymphocytes are incubated together does not significantly affect the percentage of lymphocytes forming rosettes. The graph obtained by plotting percentage of rosette formation against the ratio of SRBC to lymphocytes is similar to that resulting from the formation of bimolecular complexes. If rosette formation is analogous to formation of bimolecular complexes, maximal rosette formation occurs when the system is saturated, i.e., with excess SRBC, and is a measure of the total capacity of a lymphocyte population to form rosettes. In addition, the percentage of rosette formation observed at a limiting SRBC/lymphocyte ratio gives an indication of the avidity of the lymphocytes for SRBC. This interpretation may provide an explanation for the difference between the “active” and “total” rosettes. When the log of the SRBC/lymphocyte ratio is plotted against percentage of rosette formation, a straight line is obtained, suggesting that within a given normal lymphocyte sample, T cell subsets with different avidities are not detected by rosette formation at different SRBC/lymphocyte ratios.
Macrophage Requirements of CR- and CR+ B Lymphocytes for Antibody Production in Vitro
Authors: Hoffmann Michael K. , Hämmerling Ulrich , Simon Markus , Oettgen Herbert F. 
Published: December 2022

Abstract
A Sephadex G-10 column coated with antigen-antibody complexes and complement retains complement receptor-bearing (CR+) mouse spleen cells. The effluent is rich in thymus-derived cells (T cells), and contains bone marrow-derived cells (B cells) which carry surface immunoglobulin (Ig), Ir-associated antigen (Ia), and Fc receptors, but no complement receptors (CR-). Although both unfractionated and CR- B cell populations are capable of producing antibody to red cell antigens, they differ in their requirements for the initiation of the response. Unfractionated B cells cooperate with primed as well as unprimed helper T cells; macrophages are required for this cooperation but can be replaced by 2-mercaptoethanol. CR- B cells cooperate with primed but not with unprimed T cells provided macrophages are added to cultures. After addition of culture supernatant from BCG-activated macrophages CR- B cells cooperate with both unprimed and primed T helper cells.