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PubMed1967

Complement as a mediator of inflammation. 3. Purification of the activity with anaphylatoxin properties generated by interaction of the first four components of complement and its identification as a cleavage product of C'3.

Purified preparations of human C'1 esterase, C'4, C'2, C'3, and C'5 were labeled with (125)I. Reaction mixtures were prepared containing a single labeled component and other unlabled components. After incubation at 37 degrees C for 10 min at pH 7.4 in the presence of 5 x 10(-4)M Mg(2+), they were adjusted to pH 3.5 and subjected to sucrose density gradient ultracentrifugation and gel filtration at pH 3.5. In all cases, an activity capable of contracting guinea pig ileum with tachyphylaxis was obtained in low molecular weight fractions. However, these fractions were labeled only when (125)I-C'3 was employed, indicating that biological activity was associated with a cleavage product of C'3. This fragment has been designated F(a)C'3 in a nomenclature consistent with that of immunoglobulin degradation products. The much larger, residual portion of the C'3 molecule has been designated F(b)C'3. The biochemical characteristics of generation of F(a)C'3 were consistent with a mechanism involving action of C'1 esterase on C'4 and C'2, activation of C'2, and cleavage of C'3. F(a)C'3 had a molecular weight by gel filtration techniques of 6800 or less. It was thermostable and susceptible to inactivation by endo- and exopeptidases. The isolated fragment possessed all of the biological properties of unfractionated mixtures of C'1 esterase, C'4, C'2, and C'3. In addition to contraction of guinea pig ileum, these included failure to contract rat uterus, enhancement of vascular permeability in guinea pig skin, degranulation of mast cells in guinea pig mesentery, and release of histamine from rat peritoneal mast cells. F(a)C'3 did not cross-desensitize guinea pig ileum to rat agar anaphylatoxin and vice versa. The existence of different protein fragments with anaphylatoxin properties has been discussed. Distinctive characteristics of F(a)C'3 from classical anaphylatoxin generated by treatment of fresh rat serum with agar have been indicated.

Anaphylaxis↗
PubMed1970

Complement and complement-like activity in lower vertebrates and invertebrates.

A purified cobra venom factor with C-inhibiting activity also promotes lysis of erythrocytes in fresh mammalian serum. Lysis-inducing activity of purified cobra venom factor was found in sera of lower vertebrates including the cyclostome hagfish and in invertebrates. Lysis-inducing activity was most effective with frog serum. Frog serum was found to be more hemolytic for E(s) in the presence of CVF than when cells were sensitized with hemolysin. The hemolysis induced by CVF with frog serum, as in the higher vertebrates, was inhibited when sera were pretreated with known C inhibitors including heat, chelators, endotoxin, immune complexes, and CVF itself. Complexes formed with CVF and either frog serum or invertebrate hemolymph promoted lysis of indicator cells in the presence of frog serum in EDTA. This lysis was most marked when the starfish-CVF complex was used and was C-dependent. Conversely, complex formed with frog serum and CVF promoted lysis of E in the presence of invertebrate hemolymph (Limulus) in EDTA. Hence, serum components were to some degree at least interchangeable between vertebrate sera and invertebrate hemolymph. Lysis-inducing activity of purified CVF occurs in a wide range of species, has revealed activities resembling those of terminal C-components in lower vertebrates and invertebrates, and provides one means for study of C and C-like activities in primitive species.

Amphibians↗
PubMed1974

Interactions of C-reactive protein with the complement system. I. Protamine-induced consumption of complement in acute phase sera.

Protamine sulfate was found to consume large amounts of C selectively during preincubation with sera of individuals in the "acute phase". Marked depletion of C1, C4, and C2 with minimal, if any, depletion of C3-9, was observed. The consumption was time and temperature dependent, occurring most rapidly and extensively at 37 degrees C, 0.10 M relative salt concentration and pH 7.5-8.0; it required calcium ions. It was mediated by a heat-stable nondialyzable factor which separated with C-reactive protein (CRP) during fractionation and purification, correlated with serum CRP levels, and, like other known reactivities of CRP, was inhibited by phosphoryl choline. Preparations of CRP purified either from serum or ascites resulted in consumption of large amounts of C1, C4, and C2 when preincubated with normal serum and protamine. We conclude that CRP is a potent activator of the C system at the level of C1, and that polycations such as protamine sulfate are substrates of CRP which can bring about this activation. It seems not unlikely that one role of CRP in health and disease involves its ability to interact with the C system.

Animals↗
PubMed1975

Interactions of C-reactive protein with the complement system. III. Complement-dependent passive hemolysis initiated by CRP.

Interactions of CRP with various substrates in the presence of human serum have been shown to result in efficient activation of C components C1-C5. We now report the ability of CRP to initiate C-dependent hemolysis. For this purpose CRP was isolated by affinity chromatography using pneumococcal CPS and gel filtration; its purity was established by several criteria. Erythrocytes were coated with CPS (E-CPS) and passively sensitized with CRP. C-dependent lysis of these cells was observed upon the addition of suitably absorbed human serum, and the efficiency of hemolysis compared favorably with that initiated by rabbit IgG anti-CPS antibody. CRP also sensitized E-CPS for lysis by guinea pig C; partial lysis was seen when C4-deficient guinea pig serum was used, suggesting that CRP also shares with antibody the ability of CRP to fully activate the C system and provide further evidence for a role for CRP similar to that of antibody in the initiation and modulation of inflammatory reactions via the complete system.

Animals↗
PubMed1974

Elastase of Pseudomonas aeruginosa: inactivation of complement components and complement-derived chemotactic and phagocytic factors.

A purified elastase from Pseudomonas aeruginosa was highly destructive for fluid-phase and cell-bound C1 and C3 and fluid-phase C5, C8, and C9. Inactivation of C4, C2, C6, and C7 by the enzyme varied from 0 to 67%. Low concentrations of elastase generated, then inactivated, a chemotactic factor from human C5 but not from C3. Higher enzyme concentrations inactivated the C5 chemotactic activity at a faster rate. Elastase treatment of sensitized pseudomonads containing cell-bound C3 reduced the phagocytic indexes of polymorphonuclear leukocytes. The data support the proposed chemopathogenic role of the elastase in generation of the characteristic non-inflammatory Pseudomonas vasculitis.

Animals↗