A COMPARISON OF HUMAN AND GUINEA PIG COMPLEMENTS AND THEIR COMPONENT FRACTIONS

Development of a C3c-based ELISA method for the determination of anti-complementary potency of Bupleurum polysaccharides

Traditionally, determination of inhibitory potency of complement inhibitors is performed by the hemolytic assay. However, this assay is not applicable to the lectin pathway, thus impeding the understanding of complement inhibitors against the overall function of the complement system. The main objective of our study was to develop a specific enzyme-linked immunosorbent assay (ELISA) as an alternative method to assess the anti-complement activity, particularly against the lectin pathway. By using respective coating substrates against different activation pathways, followed by capturing the stable C3c fragments, our ELISA method can be used to screen complement inhibitors against the classical pathway and the lectin pathway. The inhibitory effect of suramin on the classical pathway, as measured by our hemolytic assay is consistent with previous reports. Further assessment of suramin and Bupleurum polysaccharides against the lectin pathway showed a good reproducibility of the method. Comparison of the lectin pathway IC₅₀ between Bupleurum smithii var. parvifolium polysaccharides (1.055 mg/mL) and Bupleurum chinense polysaccharides (0.98 mg/mL) showed that, similar to the classical and alterative pathway, these two Bupleurum polysaccharides had comparable anti-complementary properties against the lectin pathway. The results demonstrate that the described ELISA assay can compensate for the shortcomings of the hemolytic assay in lectin pathway.

INSULIN ANTIBODY VARIATIONS IN RABBITS AND GUINEA PIGS AND MULTIPLE ANTIGENIC DETERMINANTS ON INSULIN

1. A method is presented for measuring the degree to which insulin antibodies in one antiserum react with an insoluble insulin complex saturated with antibodies from a different antiserum. 2. Many rabbits produce antibodies which bind to portions of the insulin molecule to which antibodies from guinea pigs or other rabbits cannot bind. 3. Occasional guinea pigs produce antibodies which bind to portions of the insulin molecule to which antibodies from rabbits or other guinea pigs cannot bind. 4. Studies with labeled antisera and repeated incubations of test antisera with antibody insulin complexes demonstrate the individual antibody variations to be due to antibodies directed to different determinants and not to dissociation of antibodies from the same determinant on the insulin molecule. 5. More than one antibody molecule can simultaneously bind to an insulin molecule. 6. Insulin has a multiplicity of antigenic determinants. 7. The relationship between antigenic determinants, insulin antibodies, and neutralization of insulin by antisera is discussed. 8. The determinants to which insulin antibodies are directed appear to be characteristic for the individual rabbit or guinea pig immunized. It is postulated therefore that genetic factors direct antibody production toward specific determinants when insulin is the antigen.

Complement: A nostalgic journey

The scientific career and research contributions of Hans J. Müller-Eberhard to the field of complement research are presented in historical context, and interpreted with regard to the state of the field and the research technologies available when the contributions were made.

The conglutination phenomenon. VIII. A quantitative study of the components in six different complements essential for conglutination

1. A quantitative study has been made of the activity of C′1, C′2 and C′4 in the complements of the horse, cat, pig, man, guinea-pig and rabbit.

2. Evidence is presented which suggests that either there may be two types of C′4, the one haemolytic and the other conglutinating, or else that the manifestation of this complement component varies under conditions not yet understood.

3. In certain complements it appears that the serum proteins functioning as C′1 with the bovine anti-sheep red cell antibody are distinct from those functioning as C′1 with an antibody of similar specificity from an immune rabbit serum.

STUDIES ON IN VITRO ANTIBODY PRODUCTION. 3. PRODUCTION OF COMPLEMENT

Bone marrow, spleen, liver, and thymus cells of the guinea pig were incubated in Eagle"s minimal essential medium which contained glycine-2-C14. Flasks were removed from the water bath at 0, 6, 18, 24, and 48 hours and their contents were homogenized, centrifuged, and concentrated. Experiments were carried out with the concentrated supernatant samples to determine whether or not they contained proteins with properties similar to those of complement (C′) proteins. Titrations for hemolytic activity revealed that bone marrow cells produced C′2, C′3, and C′4; spleen cells synthesized C′2 and liver slices produced C′2. Liver supernatant samples also contained C′3 activity, but proteins associated with C′3 actiyity seemed to be released rather than synthesized by liver slices. We were unable to demonstrate C activity with thymus cell supernatants. Heat inactivation (56 °C for 30 minutes), as well as EDTA inhibited the hemolytic activity of supernatant samples.Further experiments showed that these supernatant proteins were fixed to antigen–antibody complexes and to aggregated gamma-globulin. The fixation was inhibited by guinea pig serum. Immunoelectrophoresis and gel-diffusion showed that proteins synthesized in vitro migrated as beta-globulins and were antigenically similar to C′ proteins.

INTERFERENCE WITH IMMUNE HEMOLYSIS BY GLYCOPROTEIN ANTIGENS

1. The titer of an individual insulin antiserum measured by hemagglutination agrees favorably with the titer of the same antiserum as measured by immune hemolysis. 2. In contrast, a marked decrease is noted in the immune hemolysis titers relative to hemagglutination titers of antisera prepared against three different sialic acid-containing proteins (human chorionic gonadotropin, rabbit transferrin, and human transferrin). 3. The lower immune hemolytic titers of glycoprotein antisera are apparently not due to a lack of complement-fixing gamma(2)-antibodies. 4. The glycoprotein antigens in solution do not interfere with hemolysis in the insulin immune system. 5. By contrast, marked inhibition of insulin immune hemolysis occurs when cells are sensitized with both glycoprotein and insulin. 6. Cells treated with neuraminidase (to remove cell surface sialic acid) lyse in the presence of C'(a) alone. 7. If neuraminidase-treated cells are sensitized with sialic acid-containing protein, the lysis of these cells by complement is inhibited. 8. It is, therefore, postulated that during some initial phase of immune hemolysis, a sialic acid-containing substrate is cleaved from the cell surface, rendering the cell susceptible to lysis. If this removal is interfered with, i.e., by sensitization of the cell with competitive sialic acid-containing antigen, then the lytic portion of immune hemolysis cannot proceed.

Mechanisms of decreased leucocyte adhesiveness and migration in plasma from patients with IgG myelomatosis

The adhesiveness of leucocytes in human plasma was decreased by the addition of IgG M-protein, commercial IgG, F(ab)2-fragments, or bovine serum albumin (BSA). Leucocyte migration was inhibited by IgG M-protein and commercial IgG, but not by reduced and alkylated IgG, F(ab)2-fragments or BSA. Guinea pig serum (GPS) strongly enhanced leucocyte migration in Hanks' balanced salt solution. This effect was abolished by hydrazine treatment or heating, and reduced, but not abolished, by zymosan treatment. C4-deficient guinea pig serum (C4-def-GPS), but not zymosan treated C4-def-GPS stimulated migration. In IgG myeloma sera migration was enhanced by the addition of C4-def-GPS and by untreated or heated, but not hydrazine treated GPS, and inhibited by zymosan treated GPS. IgG M-protein inhibits leucocyte adhesiveness and migration. Migration is specifically inhibited by the intact IgG, probably through complement activation with consumption of heat stable chemokinetic factor(s) and production of migration inhibitors.

STUDIES ON THE ACTIVATION OF A PROESTERASE ASSOCIATED WITH PARTIALLY PURIFIED FIRST COMPONENT OF HUMAN COMPLEMENT

It has been found that under a wide range of physico-chemical conditions a positive correlation exists between the rate of disappearance of hemolytically active, partially purified first component of human complement and the rate of activation of an esterase hydrolyzing N-acetyl-L-tyrosine ethyl ester. Both reactions follow the kinetic equation for second order autocatalysis, with an apparent energy of activation of 31,000 calories per mol. They occur optimally at pH 7.3-7.7 and are inhibited by ionic strengths greater than 0.15, by 5 x 10(5)M ethylenediaminetetraacetic acid, and by a heat-labile serum inhibitor which appears unrelated to any component of complement. The activation of first component to esterase resembles closely the activation of trypsinogen to trypsin. Partially purified first component, containing plasminogen, may also be activated to esterase by addition of streptokinase. The significance of these data with respect to the postulated existence of first component as a proesterase and its possible role in complement-"fixation" is discussed.

Some properties of an esterase derived from preparations of the first component of complement

Studies on an esterase derived from partially purified preparations of the first component of complement are described. The esterase hydrolyzed certain synthetic amino acid esters, among which N-acetyl-L-tyrosine ethyl ester was most susceptible. This was hydrolyzed maximally between pH 7.5 and 8.2, and at 41 degrees C. The esterase could not be identified with other previously described hydrolytic enzymes. An esterase with similar properties could also be eluted from antigen-antibody aggregates which had been treated with serum. Human serum contained a heat-labile inhibitor of the esterase which could not be identified with any of the known components of complement. The esterase was also inhibited by certain reducing agents. The experiments described support the early hypothesis that complement exerts its action enzymatically, but the physiological role of the esterase derived from preparations of complement is not yet clear.

Quantitative studies on the properdin-complement system. II. Kinetics of the reaction between properdin and zymosan

The reaction of human, bovine, and pig properdin with excess zymosan exhibits an induction period followed by a rapidly accelerating formation of the properdin-zymosan (PZ) complex. Two methods for determining the quantity of PZ complex are given, one using human serum lacking properdin, the other using a fraction of pig serum containing complement components, C'1, C'3 and C'4.

The properdin system and immunity. III. The zymosan assay of properdin

A detailed method for the zymosan assay of properdin is described, together with procedures for the preparation and standardization of reagents employed in the test. The reliability and reproducibility of the assay, as well as its limitations, are discussed.

Regression of transplanted lymphomas induced in vivo by means of normal guinea pig serum. II. Studies on the nature of the active serum constituent: histological mechanism of the regression: tests for effects of guinea pig serum on lymphoma cells in vitro: discussion

In an extension of the experimental studies recorded in an associated paper; attempts were made to isolate and characterize the constituent of guinea pig serum responsible for inducing regression of transplanted lymphomas in vivo. The active material was precipitated readily from the whole serum, along with some of the globulins, by means of ammonium sulfate in concentrations of 2.0 molar or greater; it withstood heating at 56 degrees C. for 20 or 30 minutes, but was inactivated upon heating at 66 degrees C. for similar periods; it was completely inactivated by chymotrypsin in concentrations of 1 or 2 mg./cc. during 6 hours at 37 degrees C. Furthermore, the inhibitory effects of small amounts of the guinea pig serum in vivo were enhanced upon admixture with immune sera prepared by injecting the lymphosarcoma cells into rabbits. The facts as a whole suggest that the active material is a protein, and that it may be one or another of the components of complement; yet they do not suffice to establish its identity. Microscopic studies showed that the cells of subcutaneous lymphomas rapidly died and were resorbed following injections of relatively large amounts of guinea pig serum intraperitoneally into mice carrying them, while similar changes followed more gradually after repeated injections of smaller amounts of guinea pig serum. No changes referable to the guinea pig serum were seen in the normal tissues or organs of mice receiving it. Mouse lymphoma cells, suspended artificially as individuals in a physiological saline solution, regularly remained viable following incubation in vitro in mixture with guinea pig serum during 6 hours at 37 degrees C. The finding provides strong evidence that the regression of lymphomas that follows injection of guinea pig serum in vivo is brought about through some reaction in which the guinea pig serum and the host both participate. Some of the implications of the findings are discussed.

The influence of calcium ions on the inactivation of human complement and its components by plasmin

Ca(++) potentiates the inactivation of human complement by streptokinase-activated plasmin and chloroform-activated bovine plasmin. The optimum concentration of Ca(++) varies between 10(-2)M and 10(-3)M, decreasing with increasing concentrations of streptokinase. The susceptibility of the components of complement to inactivation by plasmin is different in the presence and absence of Ca(++). C'2 and C'4 are most readily inactivated by plasmin in the presence of Ca(++), while C'1 disappears first in the absence of Ca(++). A large part of this C'1 disappearance is due to spontaneous inactivation. Similarities are pointed out between the influence of Ca(++) on the inactivation of the components of complement by antigen-antibody systems and by plasmin.

The inactivation of complement and its components by plasmin

Human complement is inactivated by plasmin, the proteolytic enzyme of plasma or serum active at or near neutrality. The addition of streptokinase to human serum, which converts plasminogen to plasmin, also causes the inactivation of complement components C'2 and C'4 and varying amounts of C'1. C'3 is the most resistant to inactivation by plasmin. Chloroform-activated human plasmin and bovine plasmin also destroy these components of complement, but are less effective than the streptokinase-activated enzyme. The inactivation of complement by the addition of streptokinase to human serum is inhibited by high hydrogen ion concentrations, low temperature, and elevated ionic strength. The inactivation of the components of complement in various fractions of serum is influenced by the available plasminogen and the content of plasmin inhibitors in these fractions. Certain similarities are pointed out between the components of complement and the factors in the plasmin system and between the inactivation of the components of complement by antigen-antibody reactions, by specific agents, and by plasmin. The possible significance of these relationships in immune hemolysis and complement fixation, and the possible role of the plasmin system in the instability of complement and the development of anticomplementary properties in serum are discussed.