Methods for the separation, purification and measurement of nine components of hemolytic complement in guinea-pig serum

Fixation of the first component of complement by immune complexes: effect of reduction and fragmentation of antibody

The integrity of both covalent and non-covalent bonds between the heavy chains of rabbit immunoglobulin gamma antibody is essential for maximal efficiency of binding of the first component of complement to immune complexes.

The significance of cutaneous immunoglobulin deposits in lupus erythematosus and NZB/NZW F1 hybrid mice

In 50 to 60 percent of patients with systemic lupus erythematosus (SLE), a band of immunoglobulins beneath the epidermis of visibly normal skin. This highly specific finding has been used as a diagnostic test (Lupus Band Test) for SLE. Similar immunoglobulin deposits are found in an inbred strain of New Zealand mice which spontaneously develop an autoimmune disease with many features of SLE. Subepidermal immunoglobulin deposits are found most frequently in SLE patients with proliferative glomerulonephritis, hypocomplementemia, and serum antibodies to native DNA (anti-nDNA). When anti-nDNA levels are suppressed by cyclophosphamide, these deposits disappear. The subepidermal accumulation of immunoglobulin in SLE patients and in the mouse model apparently depends on the presence of antibody to native DNA. It is proposed that serum anti-nDNA precipitates with nDNA which is released locally from epidermal nuclear breakdown.

The detection of the Epstein-Barr virus (EBV) nuclear antigen (EBNA) by anticomplement immunofluorescence. Immunoglobulin class of antibodies and role of complement

The Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) was detected by anti-complement immunofluorescence (ACIF) in Raji lymphoblastoid cell line, and the mechanism of the reaction explored, using Ig fractions of anti-EBNA sera and purified components of complement. Following fractionation of serum from 13 donors, anti-EBNA antibodies were always found to be associated with IgG, but were also detectable in the IgM fraction of four sera. Sequential addition of functionally pure complement components in the ACIF reaction showed that the classical sequence of complement activation in involved. Anti-EBNA antibody reactions in Raji cell nuclei can also be detected by anti-Ig immunofluorescence with a low level of sensitivity. The same pattern of granular fluorescence was observed when C3 (beta1A/beta1C), or C4 or IgG anti-EBNA antibodies were revealed with the corresponding flurescein-conjugated reagents. Blocking of the ACIF reaction was achieved with Fab 2 anti-EBNA antibody fragments, which therefore provided an appropriate specificity control for the detection of EBNA.

Chemotactic activity derived from interaction of factors D and B of the properdin pathway with cobra venom factor or C3B

Interaction of D (the activated form of D) and B, factors of the properdin pathway, with C3b (the major cleavage fragment of C3) generates a convertase, C3B, which cleaves C3 and initiates the terminal complement sequence C5-C9. A functionally analogous more stable C3 convertase, CoVFB, ir formed by substituting cobra venom factor (CoVF) for C3b. Mixtures of highly purified CoVF, B, and D were chemotactic for human neutrophil polymorphonuclear leukocytes as assessed in Boyden chambers either by microscopic enumeration of migrating cells or by counting of 51Cr-labeled cells. Control mixtures containing CoVF, B, and D, reacted in the absence of Mg++, were hemolytically inactive and devoid of chemotactic activity. Over a range of doses, the chemotactic activity of mixtures yielding CoVFB correlated with their hemolytic activity. Pretreatment of neutrophils with mixtures containing CoVFB rendered them unresponsive to subsequent chemotactic stimulation by kallikrein of C5a, indicating cross-deactivation to other chemotactic factors. Similar neutrophil deactivation occurred after exposure to a mixture of C3b, B, and D in which C3B was formed; with short incubation times and high cell concentration C3B also exhibited some chemotactic activity. The chemotactic activity of C3B and CoVFB is an example of a biologic function arising from interactions among factors of the properdin pathway per se, as distinguished from the capacity of this pathway to activate C3 and the terminal complement sequence.

Cytolytic lymphocytic cells with complement receptor in human blood. Induction of cytolysis by IgG antibody but not by target cell-bound C3

Human blood lymphocytes were fractionated on glass bead columns charged with sheep erythrocyte (Es) membranes-bearing human C3b (7,000-10,000 molecules/Es). In the passaged cells the proportion of C receptor lymphocytes was strongly reduced, in parallel with the capacity to lyse chicken erythrocytes (Ec) in the presence of IgG-rabbit anti-Ec antibody. In other experiments, lymphocytes forming rosettes with Es bearing activated rabbit complement [C(ra)] from C6-deficient rabbits were removed by centrifugation through human serum albumin-gelatine mixtures. This procedure also depleted the lymphocyte preparations of antibody-dependent cytolytic effector cells. The results suggest that rations of antibody-dependent cytolytic effector cells. The result suggest that such effector cells have receptors for human C as well as for C(ra). Lymphocytes were not able to lyse erythrocytes bearing either human C3b (similar to 30,000 molecules/Ec) or activated C(ra) in the absence if IgG antierythrocyte antibodies. Under the same experimental conditions these target cells were efficiently lysed in the presence of small amounts of IgG antitarget cell antibodies. This suggests that the interaction between the cellular Fcreceptors and the Fc part of the inducing antibodies is of special significance for the triggering of the cell-mediated lytic reaction. However, although target cell-bound C did not trigger cytolysis, it seemed to potentiate antibody-dependent cytolysis, probably by enhancing effector cell-target cell contacts.

A study of complement components C3, C5, C6, C7, C8 and C9 in chronic membranoproliferative glomerulonephritis, systemic lupus erythematosus, poststreptococcal nephritis, idiopathic nephrotic syndrome and anaphylactoid purpura

In a comparative study the hemolytic activity of C3, C5, C6, C7, C8, C9 and the C3 proactivator (C3PA) were measured in sera of 22 patients with chronic membrano-proliferative glomerulonephritis (CMPGN), 15 patients with idiopathic nephrotic syndrome, 10 patients with systemic lupus erythematosus, 7 patients with anaphylactoid purpura and 10 patients with acute poststreptococcal nephritis. In CMPGN, C3, C5, C6, C7 and C8 were low in the majority of the patients, whereas C9 and C3PA were depressed only in 21% and 11% of the patients, respectively. By contrast, C3PA and C8 showed striking depressions in the idiopathic nephrotic syndrome. In lupus erythematosus, all the C factors, including C3PA were found to be low with the exception of C9, which was normal in 80% of the patients studied. C3, C5, C6 and C7 were found to be depressed in acute glomerulonephritis; C8 and C9 titers were normal. In all patients studied with anaphylactoid purpura, CH50 and C3 titers were elevated markedly.

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.

Immunoglobulin in clinically uninvolved skin in systemic lupus erythematosus: association with renal disease

23 of 42, or 55%, of patients with systemic lupus erythematous had immunoglobulin deposits along the epidermal basement membrane of uninvolved skin (positive lupus band test [LBT]). In patients with low serum complement levels, 91% had a positive LBT), as compared with 15% in those with normal complement levels. The LBT was positive in 70% of patients with clinical and laboratory evidence of renal disease, but in only 31% of patients without renal disease. 81% of patients with the more severe histologic forms of lupus nephritis, i.e., proliferative glomerulonephritis and membranous glomerulonephritis, and positive tests, whereas only 23% with mesangial glomerulitis or normal histologic findings were positive. Immunoglobulins of the same class found in the skin were detected in the glomeruli of patients examined by renal biopsy. These results suggest that there is a relationship between the occurrence of immunoglobulin in the epidermal basement membrane and the presence of the more severe forms of lupus nephritis.

Receptor for soluble C3 and C3b on human lymphoblastoid (RAJI) cells. Properties and biologocal significance

This study describes the presence of a receptor for fluid phase human C3 and C3b on Raji cell membranes. The binding of C3 and C3b was demonstrated indirectly by a fluoresceinated anti-C3 serum and directly by using radioiodinated proteins. No other complement proteins or serum factors were needed to mediate binding of C3 and C3b to the receptor. The possibility of enzymatic cleavage of C3 before or after its attachment on the cell membrane was ruled out by the demonstration of antigenically intact C3 on Raji cells. Inhibition and dissociation of Raji cell-EAC1423 rosettes by C3 and C3b indicated that both of these proteins bind to the same receptor site or closely associated receptor sites on Raji cells. C3b-bearing Raji cells were immune adherence negative, indicating that C3b binding to the receptor is brought about through the immune adherence region of the molecule and not the C3d portion. The C3 receptor on Raji cell membranes is uniformly distributed and can move on the membrane plane. Approximately 4 x 10(5) molecules of C3 or C3b bind per Raji cell. The receptor had a higher affinity for C3 than C3b, as was shown by uptake experiments and inhibition of Raji cell-EAC1423 rosette formation. Apart from the described receptor for C3 and C3b another specific receptor for C3b inactivator-cleaved C3b (C3d) bound to red cells was shown to be present on Raji cells. Raji cells cultured in medium containing fresh normal human serum and cobra venom factor were lysed. Similar results were obtained when C3b-bearing Raji cells were cultured in medium with fresh normal human serum. The lytic effect could be abolished by inactivating serum C3 proactivator (C3PA) and required C6. It was concluded that C3b bound to the Raji cell membrane activates the complement system through the alternate pathway and results in membrane damage and cytolysis. It is postulated that cell destruction by this mechanism may play an important role in vivo in controlling cell growth.

Hereditary deficiency of the sixth component of complement in man. I. Immunochemical, biologic, and family studies

An 18-yr-old black woman in good general health was found to lack serum hemolytic complement activity. The sixth component of complement (C6) was undetectable by functional assay of serum or plasma and by immunoprecipitin analysis of serum. Functional titers of all other complement components were normal. The absence of C6 in the patient's serum could not be accounted for by a circulating C6 inhibitor, and addition of functionally pure C6 to the patient's serum restored hemolytic activity to normal. Both parents of the proband and five of six available siblings had approximately half the normal levels of functional C6. The other sibling had a normal C6 level. These data suggest that both parents and five siblings are heterozygous for C6 deficiency, while the proband is homozygous and one sibling is normal. Thus, C6 deficiency appears to follow classic mendelian inheritance, with all three possible genotypes recognizable within the family. Functional properties of the proband's C6-deficient serum included total absence of bactericidal activity against Salmonella typhi 0 901 and Hemophilus influenzae, type b, and inability to mediate lysis of red blood cells from patients with paroxysmal nocturnal hemoglobinuria in either the acidified serum or "sugar water" tests. The proband's serum did, however, exhibit a normal capacity (a) to generate chemotactic activity during incubation with bacterial endotoxin or aggregated IgG, (b) to mediate the immune adherence phenomenon, and (c) to coat human red blood cells, sensitized by cold agglutinins, with C4 and C3.

Serum heat-labile opsonins in systemic lupus erythematosus

To study possible mechanisms responsible for the increased susceptibility to infection of patients with active systemic lupus erythematosus (SLE), a study of the serum heat-labile opsonic capacity (HLOC) in such patients was undertaken. With leukocytes from normal donors, the sera of 12 of 30 patients with active SLE demonstrated decreased HLOC for E. coli 075. The phagocytic activity was partially restored by normal serum, suggesting that decreased HLOC was responsible for the defective phagocytosis. While 8 of 10 patients with active SLE and concomitant infections showed deficient opsonic capacity to E. coli 075, only 4 of 20 such patients without infections showed the defect (P = 0.01). None of 12 patients with inactive disease had deficient opsonic capacity. Similar results were obtained with S. aureus 502A as the test bacterium. In the patients surviving infection, recovery of normal serum opsonic capacity was rapid and usually coincided with an increase of serum complement to normal levels. In three patients with active SLE and infection, the causative microorganisms were isolated and opsonic capacity for these organisms tested with the individual patients' sera. In each case, sera obtained at the onset of the infectious episode had low opsonic capacity when compared with normal sera. Serum C3 proactivator levels were low in 9 of 11 sera with deficient opsonic capacity. However, similar low values were found in other SLE sera with normal HLOC, suggesting that other factors of the opsonic system were also depleted. Addition of the classical complement components C1, C4, C2, C3, and C5 to sera with deficient HLOC failed to restore activity. Addition of pure C3 proactivator also failed to restore activity. However, addition of C3 proactivator together with 50 degrees C-heated normal serum restored activity, indicating that factors active at the early steps of opsonic activation via the alternative pathway of complement were necessary to restore opsonic activity. These findings indicate that in active SLE, a decrease of components of the alternate pathway of complement activation results in an acquired defect of serum HLOC and perhaps other related complement-mediated functions. This defect may be an important factor in the increased susceptibility to infections of patients with active systemic lupus erythematosus.

Serum-mediated leukemia cell destruction in AKR mice

AKR mice with spontaneous leukemia were infused with normal serum from a variety of species. Leukemia cell destruction was produced by serum from strains of mice possessing the full spectrum of complement components, but not by serum from strains with a genetically determined deficiency of C5. Serum from guinea pigs, horses, and humans also causes destruction of leukemia cells. The antileukemic factor in normal serum was heat labile (56 degrees C for 35 min) and could be inactivated by cobra venom factor (CVF). Tests of individual complement factors from guinea pig serum and from human serum suggest that C5 is the antileukemic complement component in normal serum. Evidence was obtained that complement also plays a role in the antileukemic effect of interferon and endotoxin.

The association of respiratory infection, recurrent hematuria, and focal glomerulonephritis with activation of the complement system in the cold

The study of the activation of C3, C5, and C7 associated with the conversion of C3 in the serum of a 9-yr old girl after incubation at 0 degrees C for 6-8 h without utilization of C1, C4, and C2 is described. The patient has upper respiratory infections associated with recurrent gross hematuria, focal glomerulonephritis, and transient renal insufficiency. Histological lesions demonstrated the presence of B1c globulin IgA and properdin in the glomeruli. The activation of complement (C) in the cold requires the patient's IgA. Removal of IgA from the serum by immunoadsorption prevents activation and conversion of C3. Bactericidal and phagocytic activity is also impaired after incubation. C3 proactivator (C3PA) level is reduced before and after incubation. Properdin level drops after incubation. These findings suggest that the activation of C3 which is demonstrable in vitro may be a continuous process in vivo.

The complement system in bullous pemphigoid. I. Complement and component levels in sera and blister fluids

Compared with other serum and blister fluid proteins, total hemolytic complement was reduced in the blister fluid of six serologically positive bullous pemphigold patients while four serologically negative cases had blister fluid complement levels closely approaching the serum levels. Except for pemphigus vulgaris blisters. blister fluids from most patients with other bullous diseases and experimentally induced blisters had blister fluid complement levels more closely approaching the serum levels. With the exception of the two terminal components. C8 and C9, individual components of the complement sequence were also reduced in the blister fluids of the six bullous pemphigold patients with circulating basement membrane zone antibodies. On the other hand, transferrin and IgG levels of these same six serologically positive blister fluids closely approached the corresponding serum levels. Conversion of C3 proactivator was also demonstrable in the serologically positive bullous pemphigoid blister fluids, but not in the corresponding sera. Our studies, therefore, are suggestive of local activation of the complement sequence, by both the classical and alternate pathways, in blisters of serologically positive bullous pemphigold patients.

A new complement-mediated cytolytic mechanism--the C1-bypass activation pathway

A new cytolytic pathway is described whereby cells sensitized with cytotoxic antibody can be specifically lysed in the complete absence of intact, classical complement pathway function. Evaluation of this model with sera deficient in the 4th (C4), 2nd (C2), and 6th (C6) components of complement has revealed that this new lytic mechanism, termed the C1-bypass activation pathway, is initiated by the antibody-mediated activation of C1. Utilizing components of the previously described alternate complement pathway, this pathway bypasses C4 and C2 to activate the third to ninth components of complement (C3-9) with induction of membrane damage.

Isolation and characterization of C1q, a subcomponent of the first component of complement, from human and rabbit sera

1. C1q, a subcomponent of the first component of complement, has been isolated, in a haemolytically active and soluble form, by ion-exchange chromatography and gel filtration, from human and rabbit sera. Yields ranged from 10 to 25mg/litre of serum and the activity of final preparations was consistently in the range 5x10(3)-15x10(3) C1qH(50) units/mg. 2. The molecular weights of human and rabbit subcomponent C1q were 409600 and 417600, as determined by sedimentation equilibrium studies. 3. Subcomponent C1q from both species was shown to be composed of non-covalently linked subunits of approximately 57000 molecular weight as determined by gel-filtration or sedimentation equilibrium studies in 5.3m-guanidinium chloride. Reduction or oxidation of human and rabbit subcomponent C1q yielded three chains each having a molecular weight of approximately 23000 and which differed slightly in amino acid composition but markedly in carbohydrate content. The oxidized chains were separated, on a preparative scale, by ion-exchange chromatography in 8m-urea on DEAE-cellulose. 4. Both human and rabbit subcomponent C1q contained hydroxyproline, hydroxylysine, a high percentage of glycine and approximately 8% carbohydrate. Glutamic acid and aspartic acid were the free N-terminal amino acids of human subcomponent C1q whereas only serine was found in rabbit subcomponent C1q. 5. Collagenase digestion of human or rabbit subcomponent C1q caused a rapid loss of haemolytic activity which correlated with the breakdown of collagenous regions in the molecule.

Effect of rheumatoid factor on complement-mediated phagocytosis

The frequency and amount of IgM rheumatoid factor (RF) in the blood of patients with rheumatoid arthritis (RA) correlate with the severity of the disease and the number of complications. Though previous studies of RF in subacute bacterial endocarditis have shown that RF inhibits phagocytosis of microorganisms by granulocytes, the presence of low levels of complement (C) in blood and synovial fluid of patients with the highest titers of RF suggests that an interaction between RF and C may contribute to the inflammatory process in RA. We thus employed a quantitative methodology to examine the effect of RF on complement-dependent phagocytosis of sheep erythrocytes by rabbit granulocytes. Addition of 2500 molecules of IgM RF to sheep cells heavily coated with IgG antibody (195,000 molecules per cell) resulted in virtually complete inhibition of uptake of C3 (beta(1c)) and prevention of phagocytosis, an effect resulting from inhibition of uptake of C1 by the cells. When erythrocytes coated with only 34,000 molecules of IgG antibody were employed, phagocytosis was similarly inhibited. However the effect of RF on such cells was shown to be primarily mediated through inhibition of C4 rather than C1 uptake. Although the results do not exclude the participation of an IgM RF of higher avidity, present only in the tissues in rheumatoid inflammation, circulating IgM RF probably does not play a potentiating role in rheumatoid inflammation.

Enhancement of hemagglutination inhibition by complement

Experiments were conducted to determine the effect of specific antibody and complement on hemagglutination inhibition of influenza virus. It was found that early immunoglobulin M antibody to influenza virus inhibited the hemagglutinating capacity of the virus. When fresh guinea pig serum was added, the inhibiting capacity of the serum was elevated from four- to eightfold When guinea pig serum was treated with known complement inhibitors, it lost its capacity to enhance hemagglutination. The use of functionally purified complement components indicated that the first, second, and fourth components were necessary and sufficient for enhancement of hemagglutination inhibition by specific antibody to influenza virus.

C1r deficiency: an inborn error associated with cutaneous and renal disease

The studies of sera from two siblings with C1r deficiency are described. The brother (18 yr old) has shown clinical manifestations resembling lupus erythematosus for 5 yr, and the sister (24 yr old) has had arthralgia and recurrent episodes of rhinobronchitis since early childhood. Three siblings have died: one brother died at age 12 with symptoms similar to the disease of the male patient studied here, and two other siblings died in infancy, probably from infection. The low hemolytic C1 activity of the patients could be restored by the addition of purified C1r to their sera. Bactericidal activity and immune adherence were found to be impaired. When alternate pathways of the complement system were studied, both sera permitted activation of terminal components with endotoxin and cobra venom factor. These findings support the view that an alternate pathway for activation of the terminal portion of the complement cascade exists which does not utilize the conventional pathway operating through the usual early components.