Assay and Properties of Serum Inhibitor of C'1-Esterase

Levy, Lawrence R.; Lepow, Irwin H.

doi:10.3181/00379727-101-25034

Cited by 199 publications

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“…When complement action was permitted to occur in a single reaction stage, as in the previous study (1), immune cytotoxicity proceeded in the presence of normal human serum which contains an average of 6.4 units of inhibitor per ml. (7). An explanation for this apparent paradox is emerging from kinetic studies of the relative rates of reaction of low concentrations of C~I esterase with inhibitor and with C'4 (9).…”

Section: Discussionmentioning

confidence: 99%

“…The inhibitor, a naturally occurring heat-labile, a~-globulin, stoichiometrically inhibits the esterolytic activity of relatively high concentrations of C'I esterase (7,8). Because of limitations of sensitivity of the esterolytic assay for CPl esterase, no information is available as yet on the stoichiometry of interaction of enzyme and inhibitor at very low concentration.…”

Section: Discussionmentioning

confidence: 99%

“…Activity and solubility were unimpaired by storage for at least 1 month. One unit of C'I esterase is defined as that amount of enzyme which will liberate 0.5 micromol of fitratable acid during incubation for 15 minutes at 37 ° with N-acetyl-L-tyrosine ethyl ester under standardized conditions of assay (6,7). The preparation of Cq esterase used contained 30 #g. of nitrogen per unit of enzyme.…”

Section: Methodsmentioning

confidence: 99%

“…Activity and solubility were unimpaired by storage for at least several months. One unit of inhibitor stoichiometricaily inhibits the esterolytic activity of 10 units of C'I esterase under standardized conditions of assay (7). The preparation of inhibitor used contained 8 #g. of nitrogen per unit.…”

Section: Methodsmentioning

confidence: 99%

“…Human and various other serums contain a naturally occurring inhibitor, a heat-labile a2-globulin, which can block, under appropriate conditions, both the esterolytic and complement-interacting properties of Cq esterase (6)(7)(8)(9). The inhibitor, partially purified from human serum by ammonium sulfate fractionation and column chromatography, contains only small amounts of serum trypsin and plasmin inhibitors (8).…”

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confidence: 99%

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Studies on Immune Cellular Injury

Lepow

Ross

1960

The Journal of Experimental Medicine

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It was demonstrated in the preceding paper (1) that incubation of primary isolates of normal human amnion cells with specific rabbit antibody and normal human serum resulted in immune cellular injury as measured by two independent criteria of cytotoxicity. It was further shown that the factors in normal human serum which were required in addition to specific antibody for production of cytotoxicity were indistinguishable from components of hemolytic complement and calcium and magnesium ions. Thus, no fundamental differences were apparent between requirements for immune injury of human amnion cells (immune cytotoxicity) and immune injury of sheep or human erythrocytes (immune hemolysis) (2, 3).The sequence of action of the components of complement in immune hemolysis was deduced by Pillemer, Seifter, and Ecker (4). In further dissection of this complex system, Mayer, Levine, and their associates showed that early events in immune hemolysis involved reactions between the sensitized erythrocyte and the first and fourth components of complement (C'I and C~4) in the presence of Ca ++ . The resulting complex could then react with the second component of complement (C'2) in the presence of Mg ++, forming a complex which could react with the third component (CI3) in the absence of divalent cations. The latter reaction effected injury of the erythrocyte leading to hemolysis (2). The biochemical as opposed to the descriptive events in immune hemolysis were unknown.A large body of evidence has accumulated from this laboratory and independently from Becker's laboratory that C'I is a proenzyme which may be activated by antigen-antibody reactions (5). The active enzyme is an esterase (C'I esterase) capable of hydrolyzing certain synthetic amino acid esters, such as N-acetyl-L-tyrosine ethyl ester and p-toluenesulfonyl-L-arginine methyl *

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Studies on Immune Cellular Injury

Lepow

Ross

1960

The Journal of Experimental Medicine

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Complement Research

Rapp¹

1966

JAMA

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About 80 years ago it was discovered that fresh b blood serum is bactericidal.1 Subsequently, it was found that fresh blood serum is capable of lysing erythrocytes,2 protozoa,3 and tumor cells.4 This lytic activity is the result of the interaction of antigens located on the surface of the cell, corresponding serum antibodies, serum complement, and calcium and magnesium ions.5 The result of these interactions is the formation of discrete lesions on the surface of the cell.6 There is evidence

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