Alternative and classical complement pathway activity in sera from colostrum-fed and colostrum-deprived neonatal pigs.

Haemolytic assays were used to compare alternative and classical complement (C) pathway activities in sera obtained from neonatal pigs reared on porcine colostrum, bovine colostrum or an immunoglobulin-free synthetic diet. Dramatic increases in immunoglobulin concentrations were noted in the colostrum-fed animals during the first day of life, but there was not a concurrent, marked increase in either classical or alternative C pathway activity. Whether fed on homologous or heterologous colostrum, neonatal pigs had a similar gradual increase in alternative and classical C pathway activity in the post-natal period. If direct passive absorption of C components occurs in newborn pigs, it has only a minor influence on functional levels of alternative and classical C pathway activity in their sera. In pigs fed homologous and heterologous colostrum there was, respectively, an 83% and 80% increase in classical pathway activity, but only a 13% and 12% increase in alternative pathway activity during the first 3 days of life. Pigs fed the immunoglobulin-free synthetic diet had a 37% increase in classical C and a 24% increase in alternative C pathway activity. Part of the increase in classical C pathway activity in the post-natal period may be caused by a stimulating factor in colostrum. Most if not all of the increase in alternative C pathway activity and some of the increase in classical C pathway activity is most likely caused by normal humoral homeostatic mechanisms in the neonatal pig.     

Increased activation of the alternative complement pathway in sickle cell disease

Complement proteins play an important role in host defenses against Streptococcus pneumoniae, a major cause of serious infections in sickle cell (SS) disease. Previous studies have suggested abnormalities of the alternative complement pathway in SS disease. We measured activation of the alternative pathway in sera from patients with SS disease utilizing an enzyme immunoassay which detects C3b,P complexes, derivative of the C3b,Bb,P alternative pathway convertase. In all, 89% of SS sera had elevated concentrations of C3b,P complexes, indicative of increased alternative pathway activation. Chronic activation of the alternative pathway may contribute to impaired host defense in SS patients.     

Creatine kinase activity in sickle cell disease.

Creatine kinase activity was measured in 28 patients in the steady state of sickle cell disease and ranged from 4-45 IU/l, comparable with that found in healthy adult caucasians. Creatine kinase activity was also measured in 14 patients admitted consecutively for the treatment of vaso-occlusive sickle cell crises. Creatine kinase activity remained within the normal range in eight of these 14 patients throughout their admission; none had muscle pain or a chest syndrome. In the remaining six, three with muscle pain and three with a chest syndrome, increased activity was found on one or more days. A further 17 patients with vaso-occlusive sickle cell crises, associated with muscle pain, were studied. Creatine kinase activity was significantly raised in all 17, the mean creatine kinase activity for men was 578.8 IU/l and 210.6 IU/l for women, with the highest values (up to 1790 IU/l) found in those who had exercised before admission. Measurement of creatine kinase activity may therefore be a useful marker of muscle perturbation due to sickling.     

Bone-specific alkaline phosphatase protein, total alkaline phosphatase activity and lactate dehydrogenase in sera of patients with sickle cell disease

Serum bone-specific alkaline phosphatase protein (bAP) was evaluated as indicator of bone turnover by immunoradiometric assay (IRMA) in twenty patients with sickle cell disease and in twenty healthy control subjects. Serum bAP was also compared with serum total alkaline phosphatase activity and serum lactate dehydrogenase in the same group. The concentrations of serum bAP and serum lactate dehydrogenase were significantly higher in the study group than in the control group (p < 0.05, p < 0.01, respectively). The serum total alkaline phosphatase activity showed no significant difference with the control healthy subjects. There was no correlation between serum bAP and total alkaline phosphatase or lactate dehydrogenase levels in the patient group. In conclusion, serum bAP protein measured by IRMA can be considered a sensitive marker of bone turnover and could be especially useful as valuable non-invasive biochemical marker for identifying sickle cell patients with skeletal complications.     

Pulmonary thrombotic arteriopathy in patients with sickle cell disease.

BACKGROUND: Shortened life expectancy due to pulmonary hypertension (PH) is seen in 5% to 10% of patients with sickle cell disease. The principal factors suspected of causing PH are pulmonary thromboemboli (PE) and in situ arterial thrombosis. OBJECTIVE: To investigate the possible role that PE or in situ arterial thrombosis play in the development of PH in sickle cell disease. METHODS: Autopsies of 12 patients with sickle cell disease were correlated with clinical data from medical records. RESULTS: Right ventricular hypertrophy was present in 9 of 12 patients. Six patients with right ventricular hypertrophy had thrombi in large elastic pulmonary arteries. All patients with elastic artery thrombi had fresh or organized thrombi in small muscular pulmonary arteries. Hypertensive small arterial changes were present in 5 of these 6 patients. Six patients showed no thrombi in elastic arteries. Among these 6 patients, 3 had right ventricular hypertrophy and recent and organized thrombi, as well as hypertensive changes in small arteries. One of these 3 patients demonstrated plexiform-like lesions and fibrinoid necrosis of small arteries. Three patients without right ventricular hypertrophy had pneumonia or pulmonary edema with no identifiable pulmonary artery pathology. CONCLUSIONS: Arterial thrombosis with PH and cor pulmonale was regarded as the cause of death among most of these patients. Elastic artery thrombi are pulmonary thromboemboli, but pulmonary thromboemboli are always associated with widespread thrombosis of small arteries. Widespread thrombosis of small arteries alone was associated with PH in some cases. This finding suggests that pulmonary thromboemboli may be a late complication of PH and cor pulmonale and that an in situ thrombotic arteriopathy underlies the development of PH in most patients with sickle cell disease.     

Alternative complement pathway induction by ANCA

This Correspondence relates to "Alternative complement pathway in the pathogenesis of disease mediated by anti-neutrophil cytoplasmic autoantibodies" (Am J Pathol 2007, 170:52–64).     

Electrocardiogram analysis in adult patients with sickle cell disease

This study is an analysis of the electrocardiograms (ECGs) of 87 adult patients taken during hospital admission for sickle cell disease (homozygous S). The age range was 18 to 55 years: 38 were men and 49 were women. Seventy-two percent of all patients had abnormal ECGs. Nonspecific ST-T (NS-ST-T) wave abnormalities (53 percent) and QT interval prolongation (12 percent) were frequent. Seventy-five percent of the normal ECGs occurred in women (P < .05); and 74 percent of those with left ventricular hypertrophy (LVH) were men (P < .05). Fifteen of 21 (71 percent) patients with arrhythmias had NS-ST-T abnormalities. Systemic hypertension and ECG evidence for right-sided heart disease were rare, as was the incidence of LVH by ECG.     

Alternative complement pathway in the pathogenesis of disease mediated by anti-neutrophil cytoplasmic autoantibodies

Clinical and experimental data indicate that anti-neutrophil cytoplasmic autoantibodies (ANCAs) cause glomerulonephritis and vasculitis. Here we report the first evidence that complement is an important mediator of ANCA disease. Transfer of anti-myeloperoxidase (MPO) IgG into wild-type mice or anti-MPO splenocytes into immune-deficient mice caused crescentic glomerulonephritis that could be completely blocked by complement depletion. The role of specific complement activation pathways was investigated using mice with knockout of the common pathway component C5, classic and lectin binding pathway component C4, and alternative pathway component factor B. After injection of anti-MPO IgG, C4-/- mice developed disease comparable with wild-type disease; however, C5-/- and factor B-/- mice developed no disease. To substantiate a role for complement in human ANCA disease, IgG was isolated from patients with myeloperoxidase ANCA (MPO-ANCA) or proteinase 3 ANCA (PR3-ANCA) and from controls. Incubation of MPO-ANCA or PR3-ANCA IgG with human neutrophils caused release of factors that activated complement. IgG from healthy controls did not produce this effect. The findings suggest that stimulation of neutrophils by ANCA causes release of factors that activate complement via the alternative pathway, thus initiating an inflammatory amplification loop that mediates the severe necrotizing inflammation of ANCA disease.     

Cerebrovascular disease in sickle cell anemia patients

The cerebrovascular disease is a common complication in Sickle Cell Anemia (SCA). The objective of the present work was to determine the incidence of cerebrovascular disease in patients with SCA, through physical and radiological examination. Twenty one patients between 5 and 18 years were studied, homozygous SS, with or without history of neurologic manifestations, at the "Instituto Hematológico de Occidente, Maracaibo-Venezuela". A clinical history, neurological clinical examination and Cerebral Magnetic Resonance (CMR) were carried out on each patient. CMR showed findings of cerebrovascular disease (CVD) of the ischemic type, in 5 of 21 (23.8%) patients, 3 of them presented neurological alterations (2 with spastic hemiparesis and one with spastic tetraparesis); the other 2 presented silent CVD). The most affected artery was the cerebral media. We suggest to carry out a neurological evaluation (clinic and images) in patients with SCA, once a year, in order to detect early abnormalities of the central nervous system and to offer timely and adequate therapies, avoiding important sequels for the patient normal life development.     

Alternative pathway of complement activation by stimulated T lymphocytes. II. Elevation of cytotoxic potential against complement receptor-carrying cell lines

Exposure of lectin-stimulated (concanavalin A, phytohemagglutinin and pokeweed mitogen) blood lymphocytes to human serum or to purified C3 increased their cytotoxic capacity towards complement receptor positive targets such as Raji and Daudi cells. The lysis of complement receptor-negative lymphoblastoid cell lines was not influenced. The lytic capacity of lymphocytes exposed to 12-O-tetradecanoylphorbol 13-acetate was not elevated by human serum. Lectin-stimulated lymphocytes were previously shown to activate and bind C3. The results using lymphocytes activated in different ways and targets with or without complement receptor expression suggest that the C3b deposited on lymphocytes binds to the complement receptor on the targets. This contact elevates the avidity between the two cells as indicated also by the increased frequency of the lymphocyte-target conjugates. On the basis of immune adherence the C3 fragment bound on the lymphocytes was identified as C3b. The increase of the conjugate formation and cytotoxicity was abrogated when the target cells, Raji, were pre-exposed to purified C3d which occupy the CR2 receptor. The majority of lymphocytes responsible for the cytotoxicity were CD8⁺.     

Prevalence of antiphospholipid antibodies in patients with sickle cell disease

Structural abnormalities in erythrocyte membrane are more and more claimed as a determinant factor in the sickle cell disease pathogenesis. This being would have been provided by a new anionic phospholipids distribution and conformation. Phosphatidyl-serine exposing and phosphatidic acid enhancing would induce specific immunoglobulins synthesis. In this study, assessment of antiphospholipid antibodies prevalence was carried out among sickle cell trait patients (n = 35) and homozygous patients (n = 59) as compared to healthy subjects (n = 39). Antiphospholipid antibodies, assayed by ELISA procedure, were significantly higher among the homozygous patients than the sickle cell trait patients ones and highlighted as compared to healthy subjects. Pathologic data were only observed among homozygous patients. These specific antibodies, associated with thrombosis and haemolysis, would have constitute a morbid link and a therapeutic target of this sickness, dominated by homodynamic troubles.     

Hematologic responses of patients with sickle cell disease to treatment with hydroxyurea.

Because fetal hemoglobin contains gammaglobin chains instead of beta chains, it is not affected by the genetic defect that causes sickle cell disease. Increased levels of fetal hemoglobin decrease the tendency toward intracellular polymerization of sickle hemoglobin that characterizes this disease. Hydroxyurea is one of several cytostatic agents that have been shown to increase the production of fetal hemoglobin in some patients with sickle cell disease. We studied the effects of hydroxyurea administration in 10 hospitalized patients with sickle cell disease, each of whom was treated for three months. Seven patients responded with a 2- to 10-fold increase in fetal hemoglobin, from a mean (+/- SD) of 1.6 +/- 1.6 percent of total hemoglobin to 6.8 +/- 4.7 percent; three patients had fetal-hemoglobin levels of 10 to 15 percent of total hemoglobin. Three did not respond to treatment. Four of the patients who responded were retreated with hydroxyurea after one to four months without treatment and were found to have larger increases in fetal-hemoglobin levels. In most patients, levels were still rising at the end of the study, even after 90 days of therapy. Fetal-hemoglobin levels tended to peak at dosages of hydroxyurea that were myelosuppressive. In the patients who responded to treatment, there were significant increases in the percentage of reticulocytes and erythrocytes containing fetal hemoglobin and in the amount of fetal hemoglobin within these cells. The percentage of dense red cells decreased in the patients who responded to treatment. The tendency toward intracellular polymerization at physiologic oxygen saturation was reduced by about 33 percent in the cells containing fetal hemoglobin, whereas there was no change in the other cells. We conclude that hydroxyurea is effective in increasing the production of fetal hemoglobin, which in this study was found to be associated with a small decrease in hemolysis and an increase in hemoglobin levels despite myelosuppression. Controlled, prospective trials are necessary to establish whether these effects will lead to clinical benefit.     

Variation in serum electrolytes and enzyme concentrations in patients with sickle cell disease.

AIM--To assess levels of some biochemical variables in sickle cell disease patients from eastern Saudi Arabia during steady state and in crises states, with a view to comparing biochemical and clinical manifestations of the disease with those in other geographical locations. METHODS--Serum calcium, uric acid, total bilirubin, lactate dehydrogenase, hydroxybutyrate dehydrogenase, and haemoglobin were measured in 110 sickle cell patients when in steady state. The same variables were measured on 30 of the patients when they went into crisis. RESULTS--Serum calcium tended to be lower in sickle cell patients than in healthy controls, while uric acid tended to be in the high normal range. Crises did not make any difference to serum calcium but they increased the uric acid level significantly. All the other variables measured were significantly abnormal and more so during crises. CONCLUSIONS--Although the abnormal levels obtained for these biochemical variables in patients with sickle cell disease from eastern Saudi Arabia were similar to those from other geographical locations, there were noticeable differences in the severity of the abnormalities, which probably explains the differences in the clinical manifestations of the disease between geographical locations. Values of some of these variables could be adapted for use to monitor crises.