Abnormalities of the complement system in Reye syndrome

Sixteen patients with Reye syndrome had diminished concentration of serum complement proteins and/or hemolytic activity in the earliest blood sample. All 12 studied with hemolytic methods had significantly reduced C1 activity; total hemolytic complement activity was reduced in only three. Low Cl activity was accompanied by equivalent reduction of Cls in 11 of 12 patients; Clq was less than normal in only two of 12. Decreased levels of at least one other classical pathway complement hemolytic activity or protein concentration were found in 13 patients, whereas factor B or the alternate complement pathway was normal or elevated in the ten patients studied. The consistent reduction of Cls protein concentration in Reye syndrome suggests that early metabolic abnormalities regularly affect the production or catabolism of this protein. Although normal serum Clq concentration in the majority of these patients does not support an immune pathogenesis, decreased Clq, C4, and C2 in three patients does suggest that immune mechanisms may be responsible for the serum complement abnormalities in this latter group of patients.

Heterogeneity of the clinical syndrome in patients with systemic lupus erythematosus and genetic deficiency of the second complement component

Two patients with systemic lupus erythematosus associated with homozygous deficiency of the second complement component (SLE-C2D) illustrate the different clinical disease patterns found in patients with this illness. Despite the differences in extent and severity of clinical manifestations and serological findings, the renal disease was similar and kidney function was well preserved in both patients. Renal microscopic changes were focal and segmental, deposits of immuno-globulins and complement components were present by immunofluorescent staining, and dense deposits were seen by electron microscopy. Tubulo-reticular inclusion bodies were found in glomerular endothelial cells and lymphocytes of both patients, but not in the lymphocytes of a clinically healthy C2D sibling. The findings in these two patients stress the importance of careful evaluation to determine the presence of systemic disease in patients with SLE-C2D and suggest that an intact classic complement pathway is important in the development of severe lupus, nephritis, but is not needed in the pathogenesis of lupus skin lesions.

C4 synthesis in C4-deficient guinea pig radiation chimeras: restoration of the classic complement pathway

Bone marrow transplants from normal Albany strain guinea pigs established a functional classical pathway of complement (C) in C4-deficient (C4D) guinea pigs. Seventeen days after transplant the Albany leads to C4D chimeras had detectable C4 and total hemolytic C activities. Maximum C4 levels (2 to 8% of normal were reachered by day 73 and restored total C to 40% of normal. Classical pathway function persisted for about 150 days and, thereafter, declined to undetectable levels by day 385. In contrast, Albany guinea pigs transplanted with C4D marrow maintained normal C4 levels throughout the experiment, suggesting that the C4-producing cells are radioresistant and long-lived. Unlike unmanipulated C4D animals, Albany leads to C4D chimeras were unable to produce antibodies to guinea pig C4 when immunized with normal guinea pig serum. These experiments suggest that bone marrow cell progeny produce C4 in vivo.

Disseminated intravascular coagulation induced by Liquoid in the rat. II. Effect of heparin on hematologic and complement abnormalities and renal lesions studied by light, fluorescence, and electron microscopy

A single intravenous injection (12.5 mg.) of Liquoid (polyanethol sulfonate) was given to anticoagulated (heparinized) rats. Fibrinogen concentrations, platelet counts, total serum complement (CH50),C3 protein, and terminal components (C3 to C9) were measured. Histopathology was assessed by light, fluorescence, and electron microscopy. Heparin given before Liquoid remarkably diminished the seferity of the histologic lesions, with good correlation among light, fluorescence, and electron microscopy. Levels of clotting factors, CH50, C3 and C3 to C9, however, were not statistically different in the heparinized rats injected with Liquoid from those of animals receiving Liquoid alone. Actually C3 protein concentration was lower in the anticoagulated (Liquoid-heparin) rats. It is postulated that under the present experimental conditions, heparin did not antagonize the procoagulant and precipitating or complement-activating Liquoid effects. The attenuated histopathology observed was perhaps the result of either local or systemic, as yet undefined, heparin effects other than anticoagulation.

Endothelial injury induced by bacterial endotoxin: effect of complement depletion

The role of complement activation in the pathogenesis of endothelial injury caused by bacterial endotoxin was investigated in the rat. DNA synthesis in aortic endothelium was compared 48 hours after an intravenous injection of endotoxin (50 - 500 mug) in normal rats and in rats depleted of haemolytic complement by purified cobra venom factor. At the time of endotoxin administration the rats treated with cobra venom factor had less than 3% of the normal haemolytic complement level, their fibrinogen level was increased and clot retraction was impaired. Endotoxin stimulated endothelial DNA synthesis to the same degree in normal and in complement-depleted rats. Cobra venom factor alone did not stimulate endothelial DNA synthesis. The complement-depleted rats given 500 mug endotoxin were less thrombocytopenic than normal rats at the time of sacrifice, but the difference was not statistically significant. We conclude that the injurious effect endotoxin has on endothelium is not mediated by activation of late components of complement.

Disseminated intravascular coagulation induced by liquoid in the rat. I. Correlation of hematologic and complement abnormalities with renal lesions studied by light, fluorescence, and electron microscopy

Under the proper experimental conditions, disseminated intravascular coagulation,"an intermediary mechanism of disease," results in the classic endotoxin-induced generalized Shwartzman reaction. Other substances, such as liquoid, a highly negatively charged anticoagulant, trigger a generalized Shwartzman reaction-like phenomenon in rabbits. We studied the effects of a single high intravenous dose of liquoid (12.5 mg.) upon the rat's coagulation and complement systems and their correlation with the kidney morphology by light, fluorescence, and electron microscopy. Thrombin time was prolonged; fibrinogen, plasminogen, and factors VIII and XII concentrations were markedly decreased, whereas fibrin degradation products were increased in the experimental animals when compared with the saline-injected controls (p greater than 0.001). Total hemolytic complement, hemolytic activity of terminal components (C3 to C9), and C3 protein concentration were significantly reduced (p greater than 0.001). The liquoid-injected rats developed cortical necrosis and manifested oliguria and anuria, with elevated blood urea nitrogen levels, when survival was longer than 3 hours. Histologically, thrombi of fibrin-like material filled the glomerular capillaries. Deposits of fibrin, and also of immunoglobulin G and C3, were readily identifiable by specific immunofluorescence, Linear or granular fluorescent deposits (or both) along the glomerular basement membranes and in the mesangium were observed. Electron microscopy demonstrated necrosis of glomeruli and abundant thrombi of fluffy, compact granular, or fibrillar electron-dense material. No typical fibrin periodicity was detected. These experiments support the concept of activation of the coagulation and the complement systems. We postulate that liquoid produced not only a consumptive coagulopathy in the rat but also a direct or perhaps anindirect activation of complement. Whether this latter has occurred through the classic or an alternate pathway remains to be elucidated.

Combined immunodeficiency disease associated with adenosine deaminase deficiency. Report on a workshop held in Albany, New York, October 1, 1973

Fifty-five children with CID and known ADA status were studies at a workshop held in Albany, New York. Erythrocyte ADA determinations were performed in 22 of the 55 patients, 13 of whom were ADA negative. The ADA defect appears to be transmitted as an autosomal recessive trait. Some patients with CID and ADA deficiency have characteristic radiologic abnormalities of the skeleton, which are not found in other illnesses. The thymus glands of all patients with CID and ADA deficiency who could be examined have evidence of thymic involution manifested by presence of Hassall's corpuscles and differentiated germinal epithelium; this is in contrast to "classic" thymus findings in CID with normal ADA. Adenosine deaminase probably plays an important, although as yet undefined, role in lymphocyte development and/or function. The deficiency of ADA in CID is the first enzyme defect observed in a deficiency disease of specific immunity.

Reduced haemolytic C1 activity in serum of hypogammaglobulinaemic chickens

Sera from hypogammaglobulinaemic chickens, aged 22–44 days, and age-matched controls were assayed for C1 haemolytic activity by three methods, two involving cell intermediates (EAIgMC4 and EAckC4) and the third an EAck and a guinea-pig R1. Total haemolytic complement (C) was also titrated using rabbit erythrocytes bearing chicken antibody. Immunoglobulin status was monitored by immunoelectrophoresis. C1 activity was reduced in the hypogammaglobulinaemic chickens by all three assay methods, and the differences were highly significant statistically. Total C also tended to be lowered in the hypogammaglobulinaemic group, but the depression was of borderline significance. Thus, hypogammaglobulinaemic chickens have a functional deficiency of C1 at least as pronounced as that of patients with X-linked recessive agammaglobulinaemia.

Haemolysis in chicken serum. II. Ontogenetic development

Development of total complement (C) and C1 activity was followed in Line 96 chickens from day 13 of embryonic life to 40 days post-hatching. Both activities were demonstrable on day 13, and levels rose slowly in the late prehatching period. At hatching, on day 21, there was a sharp rise in both activities; both titres were roughly five times those of day 19 embryos. Further increases were seen to about day 10, followed by a levelling off (perhaps even a drop in the case of C1) for about 10 days. On about the twenty-first day the titration curve rose again. The source of the C detected in the embryo and young chicken is unknown. The pattern is consistent with transfer from the egg, but it might also reflect synthesis by the developing animal.

Haemolysis in chicken serum. I. The ionic environment

Immune haemolysis in chicken serum was examined using rabbit cells, sensitized with chicken antibody. Salt concentration was a major influence on complement activity: titres were greatly increased at ionic strengths which sustain negligible activity of human, rabbit, or guinea-pig complements. Sensitivity of the assay was also increased if standard Mg^{+ +} was lowered to 7.5 × 10^-4M and Ca^{+ +} increased to 6–9 × 10^-4M. Cobalt ion and Ba^{+ +} facilitated complement activity; Ni^{+ +} did not. Cobalt ion seemed to act as an Mg^{+ +} substitute, and barium as a replacement for Ca^{+ +}. The kinetics of haemolysis in this system resembled those of human complement: a rapid initial rate, followed by a slower one, but no levelling off at 4 hours.

Natural antibody to rabbit cells may be excluded from the titration by absorption or by limiting Mg^{+ +} in the buffer. The nature of this Mg^{+ +} dependence is unknown.

Sub-units of the first complement component in immunologic deficiency syndromes: independence of Cls and Clq

Normal concentrations of C1 esterase, C1s, have been found in nineteen individuals with a variety of immunologic deficiency syndromes. C1q levels are markedly low in patients with lymphopenic hypogammaglobulinaemia. The lack of correlation of serum concentrations of C1s with C1q in several patients suggests a separate mode of synthesis or catabolism for these C1 subunits. Furthermore, the extreme C1q deficiency in lymphopenic hypogammaglobulinaemic patients may play a role in their serious prognosis; however the normal C1s concentrations would allow some complement mediated functions.