Anaphylatoxin in its relation to the complement system

The occurrence of cryoproteins in synovial fluid; the association of a complement-fixing activity in rheumatoid synovial fluid with cold-precipitable protein

A significant portion of a complement-fixing activity found in the synovial fluid of patients with rheumatoid arthritis, and previously implicated as a possible cause of the low synovial fluid complement levels in these patients behaves as a high solubility cryoprotein. Analysis of rheumatoid synovial fluid cryoproteins has revealed mixed immunoglobulins, bound complement components, fibrinogen, DNA, and rheumatoid factor. Sorbitol density gradient studies on whole synovial fluid before and after removal of this activity has shown that the complement-fixing activity migrates in the 19S and heavier regions and that portion is removed with cryoprecipitation. Cryoproteins found in nonrheumatoid synovial fluid are generally devoid of complement-fixing activity and predominantly contain fibrinogen. DNA and IgG are also present, with IgG occurring significantly less frequently than in rheumatoid cryoproteins. These findings are discussed in relationship to recent studies demonstrating the presence of complement-fixing antibody to denatured DNA in rheumatoid cryoproteins.

Complement system in synovial fluids from patients with rheumatoid arthritis

Images

C3 leukotactic factors produced by a tissue protease

When various rat tissues are incubated in homologous serum, a factor chemotactic in vitro for neutrophils is generated. The amount of chemotactic activity is a function of duration of incubation and the quantity of heart tissue or serum employed. Addition of trypsin inhibitor or antibody to the third component of complement (C3) precludes generation of chemotactic activity. In addition, antibody to C3 ablates chemotactic activity even after its formation. Purified human C3 (beta(1C)-globulin) effectively substitutes for serum in the generation of chemotactic activity by heart tissue. The active product, as determined by gel filtration or by ultracentrifugal analysis in a sucrose density gradient, appears to be a cleavage product of C3 with a molecular weight of approximately 14,000. In addition, a larger C3 fragmentation product varying in molecular weight, depending upon experimental conditions, is also found. The protease in rat heart tissue capable of cleaving C3 into chemotactic fragments is a serine esterase with trypsin-like properties and can be inhibited by organophophorous compounds or trypsin inhibitors. The use of amino acid esters in the manner of competitive substrate inhibition confirms the trypsin-like nature of the protease. The presence of a protease in heart, and presumably in other normal tissues, capable of fragmenting C3 into factors with chemotactic activities may explain the development of the acute inflammatory response when tissues are non-specifically injured. If true, this would reinforce the role of the complement system in the mediation of nonimmunologically induced inflammation.

A specific inactivator of mammalian C'4 isolated from nurse shark (Ginglymostoma cirratum) serum

A material which specifically inactivates mammalian C'4 was isolated from low ionic strength precipitates of nurse shark serum. The C'4 inactivator was not detected in whole serum. The conditions of its generation and its immunoelectrophoretic behavior seem to indicate that it is an enzymatically formed cleavage product of a precursor contained in whole shark serum. The inactivator was partially purified and characterized. It had an S-value of 3.3 (sucrose gradient) which was in agreement with its retardation on gel filtration, was stable between pH 5.0 and 10.0, had a half-life of 5 min at 56 degrees C, pH 7.5, was inactivated by trypsin and was nontoxic. Its powerful anticomplementary activity in vitro and in vivo was solely due to the rapid inactivation of C'4; no other complement components were affected. No cofactor requirement was observed for the equally rapid inactivation of highly purified human and guinea pig C'4. The kinetics of C'4 inactivation and TAME hydrolysis, the greater anodic mobility of inactivated human C'4, and the influence of temperature on the rate of inactivation suggest that the inactivator is an enzyme and C'4 its substrate. This conclusion was supported by the more recent detection of a split product of C'4. Intravenous administration of the C'4 inactivator could prevent lethal Forssman shock and suppress the Arthus reaction in guinea pigs; it prolonged significantly the rejection time of renal xenografts but had no detectable effect on passive cutaneous anaphylaxis. Anaphylatoxin could be generated in C'4 depleted guinea pig serum with the cobra venom factor, but not with immune precipitates. The possible relationship between C'1 esterase and the C'4 inactivator is discussed on the basis of similarities and dissimilarities.

Permeability-increasing activity in hereditary angioneurotic edema plasma. II. Mechanism of formation and partial characterization

Plasma from persons with hereditary angioneurotic edema readily developed the capacity to increase vascular permeability and to induce the isolated rat uterus to contract. Both activities resided in a small, heat-stable molecule that was apparently a polypeptide. Crude preparations of the polypeptide were inactivated during incubation with trypsin. They also failed to produce pain and erythema, but caused markedly increased vascular permeability in human skin. These characteristics differ from those of bradykinin, from which crude preparations of the polypeptide could also be distinguished by electrophoretic mobility and paper chromatographic behavior. Proof that the polypeptide is truly different from bradykinin must await its further purification. Histamine played no role in the activities observed. Although the enzymes functioning to release the permeability factor and kinin activities in hereditary angioneurotic edema plasma were not clearly defined, one or more plasma enzymes other than C'1 esterase presumably participated either in conjunction with C'1 esterase or in pari passu events to release the polypeptide mediating these activities.

Passive hemolysis by serum and cobra venom factor: a new mechanism inducing membrane damage by complement

The studies presented here indicate that activation of the complement (C') system by a foreign protein will cause membrane injury and passive lysis of unsensitized erythrocytes present at the time of the reaction. These observations suggest that in addition to the classical antibody-C'-induced cytolysis, there are alternative pathways or mechanisms for activation and participation of the terminal C' components in the production of cell membrane injury. We have shown that a substance derived from cobra venom and eluted from a single protein band on polyacrylamide can promote lysis of unsensitized autologous or heterologous erythrocytes in the presence of fresh guinea pig serum and that this lysis-inducing activity and C'-inhibiting activity appear to reside in the same fractions. The lytic activity is prevented by several agents known to impair classical C'3 activity, but is unaffected by certain procedures which interfere with the function of C' components C'1 and C'2, a suggestion that this reaction involves chiefly C'3-C'9. Further, the cobra venom (CV) factor depletes C' activity in cobra serum, and the CV factor (with its 5S serum cofactor) converts purified C'3 to its inactive form,(1) indicating that the reaction of this complex with the complement system occurs without participation of antibody. Therefore, since the lysis-inducing and C'-inhibiting activity of the CV factor appear to result from similar interactions with the complement system, these observations suggest that cell membrane damage and cell lysis can be accomplished through activation of the complement system by a mechanism involving little or no participation of classical antibody or C' components C'1, 4, or 2.

Chemotactic and anaphylatoxic fragment cleaved from the fifth component of guinea pig complement

The fifth component of guinea pig complement, with a sedimentation coefficient 7.8S, is cleaved by sensitized sheep erythrocytes treated with the first four components of complement into two fragments with sedimentation coefficients of 7.4S and 1.5S. The smaller fragment, with a molecular weight of about 15,000, possesses chemotactic activity for rabbit polymorphonuclear leukocytes, as well as anaphylatoxic activity for guinea pig ileum.

Concanavalin A in vivo: induction of hemorrhagic skin lesions (Arthus-like reactions) in mice

Concanavalin A injected into the skin of mice induced the formation of hemorrhagic Arthus-like lesions. No lesions resulted if concanavalin A was adsorbed with insoluble (a2)- macroglobulin or if mice were first treated with nitrogen mustard. The ability of concanavalin A, phytohemagglutinin, or pokeweed mitogen to induce skin lesions seemed to parallel their ability to precipitate serum proteins.

Effect of C'1 esterase on vascular permeability in man: studies in normal and complement-deficient individuals and in patients with hereditary angioneurotic edema

When purified human C'1 esterase is injected intradermally in man, increased vascular permeability results. This effect is not blocked by soybean trypsin inhibitor and is not abolished by pretreatment with the antihistamine, pyribenzamine, or by compound 48/80. Thus, the effect is not due to the release of endogenous histamine. The decreased permeability response of individuals with a specific hereditary deficiency of C'2 is evidence for the complement-dependent nature of this reaction. The apparently normal response to intradermal C'1 esterase developed by individuals with an acquired specific deficiency of C'3 suggests that the vasoactive substance may be derived from one of the early reacting complement components. Characteristic attacks of angioedema have been provoked by the intradermal injection of human C'1 esterase in two individuals with hereditary angioneurotic edema. Patients with hereditary angioneurotic edema are unresponsive to intradermal injections of C'1 esterase immediately after attacks.

Interactions of the complement system with native and chemically modified endotoxins

Endotoxic lipopolysaccharides (LPS) isolated from Serratia marcescens, Veillonella alcalescens, and Salmonella typhosa were potent in their ability to induce fixation of complement (C') in normal guinea pig, rabbit, mouse, and human serum. The C'-fixing ability of LPS was pronounced even when assays were performed in undiluted serum, and was lost after each of four chemical modifications which resulted in loss of biological toxicities. The detoxification procedures had in common the cleavage of ester-bound, long-chain carboxylic acids. The ability of biologically active LPS to fix C' in normal guinea pig serum was reflected chiefly in dramatic uptake of classical C'3 (C'3t); fixation of C'1, C'4, and C'2 was virtually undetectable. Hence, it was the capacity for fixation of C'3t which was lost most overtly during detoxification. Addition of immune serum to the assay mixtures resulted in detectable fixation of C'1 and C'4. Biologically active LPS also fixed more of these components than did detoxified LPS. Immune serum restored the ability of detoxified LPS to fix C'3t, but whether this is by the original pathway is not yet clear. We concluded that the loss of certain biological activities and the loss of ability to fix C'3t in normal serum after LPS detoxification involved loss or rearrangement of substrates on LPS which either initiated or supported, or both, its interaction with the complement system. It was apparent that the ability to fix C' can serve as a valuable in vitro indicator of the integrity of the toxic conformation of biologically active LPS membrane fragments. These experiments supported the hypothesis that certain of the biological activities induced by endotoxins are mediated via the complement system.

The derivation of two distinct anaphylatoxin activities from the third and fifth components of human complement

Anaphylatoxin activity was derived from both human C'5 and C'3 molecules. This was achieved in the case of C'5 by interaction with trypsin or with EAC'4, (oxy)2a, 3. The smooth muscle-contracting material obtained from the treated C'5 was found to be a fragment of approximately 9,000-11,000 molecular weight. Its action was inhibited with antihistamine. The trypsinized C'5 also increased vascular permeability in guinea pig skin. When human C'3 was incubated with C'3 inactivator complex, which consists of a cobra venom protein and a beta-globulin of human serum, anaphylatoxin activity was observed. The activity was associated with a fragment cleaved from the C'3 molecule, having a molecular weight of between 6,000 and 15,000 as determined by gel filtration techniques. Similar activity was derived from C'3 by the C'3-converting enzyme in free or in cell-bound form. The C'5 anaphylatoxin failed to cross-desensitize guinea pig ileum to the contracting capacities of C'3 and guinea pig anaphylatoxin and vice versa. Anaphylatoxin prepared from C'3 by all methods mentioned above caused cross-desensitization to the other C'3 derivatives, but failed to desensitize to guinea pig anaphylatoxin.

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.