A Novel Strategy to Identify Haematology Patients at High Risk of Developing Aspergillosis

Invasive Aspergillosis (IA), typically caused by the fungus Aspergillus fumigatus, is a leading cause of morbidity and mortality in immunocompromised patients. IA remains a significant burden in haematology patients, despite improvements in the diagnosis and treatment of Aspergillus infection. Diagnosing IA is challenging, requiring multiple factors to classify patients into possible, probable and proven IA cohorts. Given the low incidence of IA, using negative results as exclusion criteria is optimal. However, frequent false positives and severe IA mortality rates in haematology patients have led to the empirical use of toxic, drug-interactive and often ineffective anti-fungal therapeutics. Improvements in IA diagnosis are needed to reduce unnecessary anti-fungal therapy. Early IA diagnosis is vital for positive patient outcomes; therefore, a pre-emptive approach is required. In this study, we examined the sequence and expression of four C-type Lectin-like receptors (Dectin-1, Dectin-2, Mincle, Mcl) from 42 haematology patients and investigated each patient's anti-Aspergillus immune response (IL-6, TNF). Correlation analysis revealed novel IA disease risk factors which we used to develop a pre-emptive patient stratification protocol to identify haematopoietic stem cell transplant patients at high and low risk of developing IA. This stratification protocol has the potential to enhance the identification of high-risk patients whilst reducing unnecessary treatment, minimizing the development of anti-fungal resistance, and prioritising primary disease treatment for low-risk patients.

Evolutionary loss of inflammasomes in the Carnivora and implications for the carriage of zoonotic infections

Zoonotic pathogens, such as COVID-19, reside in animal hosts before jumping species to infect humans. The Carnivora, like mink, carry many zoonoses, yet how diversity in host immune genes across species affect pathogen carriage is poorly understood. Here, we describe a progressive evolutionary downregulation of pathogen-sensing inflammasome pathways in Carnivora. This includes the loss of nucleotide-oligomerization domain leucine-rich repeat receptors (NLRs), acquisition of a unique caspase-1/-4 effector fusion protein that processes gasdermin D pore formation without inducing rapid lytic cell death, and the formation of a caspase-8 containing inflammasome that inefficiently processes interleukin-1β. Inflammasomes regulate gut immunity, but the carnivorous diet has antimicrobial properties that could compensate for the loss of these immune pathways. We speculate that the consequences of systemic inflammasome downregulation, however, can impair host sensing of specific pathogens such that they can reside undetected in the Carnivora.

Salmonella Flagellin Activates NAIP/NLRC4 and Canonical NLRP3 Inflammasomes in Human Macrophages

Infection of human macrophages with Salmonella enterica serovar Typhimurium (S. Typhimurium) leads to inflammasome activation. Inflammasomes are multiprotein complexes facilitating caspase-1 activation and subsequent gasdermin D-mediated cell death and IL-1β and IL-18 cytokine release. The NAIP/NLRC4 inflammasome is activated by multiple bacterial protein ligands, including flagellin from the flagellum and the needle protein PrgI from the S. Typhimurium type III secretion system. In this study, we show that transfected ultrapure flagellin from S Typhimurium induced cell death and cytokine secretion in THP-1 cells and primary human monocyte-derived macrophages. In THP-1 cells, NAIP/NLRC4 and NLRP3 played redundant roles in inflammasome activation during infection with S. Typhimurium. Knockout of NAIP or NLRC4 in THP-1 cells revealed that flagellin, but not PrgI, now activated the NLRP3 inflammasome through a reactive oxygen species- and/or cathepsin-dependent mechanism that was independent of caspase-4/5 activity. In conclusion, our data suggest that NLRP3 can be activated by flagellin to act as a "safety net" to maintain inflammasome activation under conditions of suboptimal NAIP/NLRC4 activation, as observed in THP-1 cells, possibly explaining the redundant role of NLRP3 and NAIP/NLRC4 during S. Typhimurium infection.

Macrophage reprogramming for therapy

Dysfunction of the immune system underlies a plethora of human diseases, requiring the development of immunomodulatory therapeutic intervention. To date, most strategies employed have been focusing on the modification of T lymphocytes, and although remarkable improvement has been obtained, results often fall short of the intended outcome. Recent cutting-edge technologies have highlighted macrophages as potential targets for disease control. Macrophages play central roles in development, homeostasis and host defence, and their dysfunction and dysregulation have been implicated in the onset and pathogenesis of multiple disorders including cancer, neurodegeneration, autoimmunity and metabolic diseases. Recent advancements have led to a greater understanding of macrophage origin, diversity and function, in both health and disease. Over the last few years, a variety of strategies targeting macrophages have been developed and these open new therapeutic opportunities. Here, we review the progress in macrophage reprogramming in various disorders and discuss the potential implications and challenges for macrophage-targeted approaches in human disease.

NLR in eXile: Emerging roles of NLRX1 in immunity and human disease

NLRX1 is a member of the NOD-like receptor family, a set of pattern recognition receptors associated with innate immunity. Interestingly, NLRX1 exists in somewhat of an exile from its NLR counterparts with unique features that mediate atypical functions compared with traditional NOD-like receptors (NLRs). Aside from a mitochondrial targeting sequence, the N-terminal region is yet to be characterized. Mitochondrially located, NLRX1 sits within a subgroup of regulatory NLRs responsible for negatively regulating cellular inflammatory signalling. As well as modulating pathogen response, emerging evidence is implicating NLRX1 as a central homeostatic gatekeeper between mitochondrial biology and immunological response. More recently, NLRX1 has been implicated in a wide range of disease, both pathogen-driven and otherwise. Emerging links of NLRX1 in cancer biology, autoimmunity and other inflammatory conditions are raising the potential of targeting NLRX1 therapeutically, with recent studies in inflammatory bowel disease showing great promise. Within this review, we address the unique features of NLRX1, its roles in innate immune signalling and its involvement in a range of inflammatory, metabolic and oncology disease indications with a focus on areas that could benefit from therapeutic targeting of NLRX1.

Tissue-resident macrophages actively suppress IL-1beta release via a reactive prostanoid/IL-10 pathway

The alarm cytokine interleukin‐1β (IL‐1β) is a potent activator of the inflammatory cascade following pathogen recognition. IL‐1β production typically requires two signals: first, priming by recognition of pathogen‐associated molecular patterns leads to the production of immature pro‐IL‐1β; subsequently, inflammasome activation by a secondary signal allows cleavage and maturation of IL‐1β from its pro‐form. However, despite the important role of IL‐1β in controlling local and systemic inflammation, its overall regulation is still not fully understood. Here we demonstrate that peritoneal tissue‐resident macrophages use an active inhibitory pathway, to suppress IL‐1β processing, which can otherwise occur in the absence of a second signal. Programming by the transcription factor Gata6 controls the expression of prostacyclin synthase, which is required for prostacyclin production after lipopolysaccharide stimulation and optimal induction of IL‐10. In the absence of secondary signal, IL‐10 potently inhibits IL‐1β processing, providing a previously unrecognized control of IL‐1β in tissue‐resident macrophages.

Measles virus hemagglutinin protein expressed in transgenic lettuce induces neutralising antibodies in mice following mucosal vaccination

Plant-made oral vaccines have the potential to overcome many of the limitations of traditional vaccines. Here we report on progress towards a lettuce-made measles vaccine. Lettuce is a palatable species which exhibits rapid growth in contained hydroponic systems and produces negligible quantities of toxins. Measles virus hemagglutinin (MV-H) protein was successfully expressed in transgenic lettuce and found to be immunogenic in mice. Lettuce extracts containing MV-H protein induced MV neutralising antibodies following intraperitoneal injection and intranasal inoculation of mice. Using a sequential prime-boost strategy in which mice were vaccinated with MV-H DNA followed by an orally delivered freeze-dried MV-H lettuce formulation a 10-fold increased in MV-specific IgG titers was observed relative to mice vaccinated with control lettuce formulations (p=0.05). MV-H protein was stable in freeze-dried lettuce for up to 13 months at room temperature, and survived at least a week at temperatures as high as 50 degrees C. This research represents a significant step towards the development of measles vaccine formulation that is effective, temperature-stable, easy to administer in a resource-poor setting and amenable to large scale manufacture.

Crude saponins improve the immune response to an oral plant-made measles vaccine

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.

Educating future physicians for Ontario

In 1987, Ontario's physicians conducted a strike, ultimately not successful, over the issue of "extra billing." The fact that the Ontario public did not support this action reflected a major gap between the profession's view of itself and the public's view of the profession. In 1990, the province's five medical schools launched a collaborative project to determine more specifically what the people of Ontario expect of their physicians, and how the programs that prepare future physicians should be changed in response. The authors report on the first five years of that ongoing project. Consumer groups were asked to state their views concerning the current roles of physicians, future trends that would affect these roles, changes in roles they wished to see, and suggestions for changes in medical education. Methods used included focus groups, key informant interviews, an extensive literature review, and surveys, including a survey of health professionals. Concurrently, inter-university working groups prepared tools and strategies for strengthening faculty development, assessing student performance, and preparing future leadership for Ontario's medical education system. Eight specific physician roles were identified: medical expert, communicator, collaborator, health advocate, learner, manager ("gatekeeper"), scholar, and "physician as person." Educational strategies to help medical students learn to assume these eight roles were then incorporated into the curricula of the five participating medical schools. The authors conclude that the project shows that it is feasible to learn specifically what society expects of its physicians, to integrate this knowledge into the process of medical education reform, and to implement major curriculum changes through a collaborative, multi-institutional consortium within a single geopolitical jurisdiction.

Demand-side medical education: educating future physicians for Ontario

Initiated by Associated Medical Services (AMS), Educating Future Physicians for Ontario is a 5-year collaborative project whose overall goal is to make medical education in Ontario more responsive to that province's evolving health needs. It is supported by AMS, the five universities with medical schools or academic health sciences centres and the Ontario Ministry of Health. The project's five objectives are to (a) define the health needs and expectations of the public as they relate to the training of physicians, (b) prepare the educators of future physicians, (c) assess medical students' competencies, (d) support related curricular innovations and (e) develop ongoing leadership in medical education. There are several distinctive features: a focus on "demand-side" considerations in the design of curricula, collaboration within a geopolitical jurisdiction (Ontario), implementation rather than recommendation, a systematic project-evaluation plan and agreement as to defined project outcomes, in particular the development of institutional mechanisms of curriculum renewal as health needs and expectations evolve.

Setting educational priorities for learning the concepts of population health

Following the World Health Organization's policy of 'Health for All by the Year 2000', doctors are increasingly being seen as health care providers to populations of patients, in addition to their more traditional role as doctors to individuals in a one-to-one encounter. In order for doctors to take on this expanded role, they must learn the knowledge and skills appropriate to population health. In this paper, we propose a method of educational priority-setting which allows educational planners to identify those diseases and adverse health conditions most appropriate for studying the concepts of population health. Using the Measurement Iterative Loop of Tugwell and colleagues as a framework, a table of Priority Illness Conditions was developed and compared with a previous priority list developed from a survey of clinical teachers at the McMaster University Medical School. Discussion of the implications for this approach in setting educational priorities at undergraduate, postgraduate and continuing medical education levels is presented, along with a review of possible shortcomings and caveats in using this approach.

Effect of prostaglandins on complement production by tissue macrophages

Tissue macrophages produce several proteins of the complement system. The mechanisms that regulate this process are poorly understood. The established ability of certain prostaglandins to influence macrophage secretory activity suggests that these lipid mediators may also modulate complement production (CP). Using the guinea pig peritoneal macrophages, we determined the effects of selected prostaglandins on in vitro CP and found that PGE2 inhibited production of complement proteins but not lysozyme; the response of elicited and resident peritoneal cells to PGE2 was identical; and PGE1, PGF2 alpha, and PGI2 had no detectable effect. PGE2 may contribute to regulation of CP in vivo.

Arachidonic acid-mediated and serum-opsonized-zymosan-mediated inhibition of complement production by macrophages. Lack of requirement for endogenous arachidonic acid metabolites

The ability of exogenous prostaglandins to inhibit complement production (CP) by monocytes and macrophages (M phi) suggests that endogenous arachidonic acid metabolites produced by these cells may also regulate their rate of CP. We assessed the regulatory influence of endogenous metabolites on CP by M phi utilizing exogenous arachidonic acid and serum-opsonized zymosan as stimulators of production of cyclooxygenase and lipoxygenase metabolites. The results of this study show that (i) the inhibition of CP caused by both agents is is independent of arachidonic acid metabolites, suggesting that endogenously produced metabolites do not influence CP, and (ii) arachidonic acid and serum-opsonized zymosan inhibit production by independent mechanisms.

C5a and antigen-induced tracheal contraction: effect of a combination of an antihistamine and cyclo-oxygenase inhibitors

Our previous studies with C5a, a cleavage product of the fifth component of complement, have shown that the antihistamine diphenhydramine and the cyclo-oxygenase inhibitor aspirin do not inhibit the C5a-induced contraction of isolated guinea pig trachea (Regal, Eastman & Pickering, 1980; Regal & Pickering, 1981). We investigated the effect of cyclo-oxygenase inhibitors in the presence of diphenhydramine to determine if cyclo-oxygenase products were contributing to the contraction beyond any effect they might have on histamine release. A combination of a cyclo-oxygenase inhibitor and diphenhydramine caused a delay in onset and decrease in magnitude and duration of the C5a-induced contraction. Indomethacin itself also caused a slight inhibition. In contrast, a combination of aspirin and diphenhydramine did not inhibit the initial portion of antigen-induced tracheal contraction any more than diphenhydramine alone and enhanced the later portion just as aspirin alone. Cross tachyphylaxis experiments demonstrated that antigen pretreatment significantly inhibited a subsequent C5a-induced tracheal contraction, though C5a pretreatment did not affect a subsequent antigen-induced contraction. Thus, cyclo-oxygenase products do contribute to C5a-induced tracheal contraction, and histamine participation in the presence of cyclo-oxygenase inhibitors is suggested. Our studies demonstrate the dissimilarities of C5a and antigen-induced contraction as regards inhibition by aspirin plus diphenhydramine, yet suggest common pathways leading to the contractile response as evidenced by cross tachyphylaxis experiments.

Enhancement of granulocyte oxidative metabolism in sera from patients with C2 deficiency and systemic lupus erythematosus

Serum or plasma from 3 patients with C2 deficiency (C2D) and systemic lupus erythematosus (SLE) significantly enhanced chemiluminescence and superoxide anion production by polymorphonuclear leukocytes (PMN) after stimulation with phorbol myristate acetate or latex beads. PMN from patients and normal individuals were supranormally activated when resuspended in plasma from these patients. No such effect was seen with plasma from a patient with C2D but with no evidence of SLE, from patients with SLE but not C2D, from patients with C1q or C8 deficiency, from C4-deficient guinea pigs, or NZB-NZW mice. Because oxygen-derived free radicals may cause joint or tissue damage, C2D patients who have or develop this activity in their plasma may be more prone to SLE or other collagen-vascular diseases.

Deficiency of the second complement component association with the HLA haplotype A10, B18 in a normal population

Serum C2 activity was measured in 135 individuals drawn from a panel of 418 tissue-typed blood donors. The study group included all donors with HLA antigens A10 and B18. Heterozygote C2 deficiency (C2Dhet) was defined by reference to the range of C2 activity in previously studied obligate heterozygotes. Five donors were C2Dhet. Family studies confirmed that C2Dhet was associated in all instance with an A10, B18 haplotype. The minimum frequency for C2Dhet was 1.2% in the panel of 418 donors and 62.5% in those donors with an A10, B18 haplotype.

Phagocytosis, chemoluminescence, and intracellular killing of fungi by phagocytes from subjects with deficiency of the second component of complement

The capacity of phagocytes from animals or humans with complement component deficiency to ingest and kill Candida albicans has been much disputed. We show that peripheral blood polymorphonuclear leukocytes and mononuclear phagocytes from subjects with hereditary C2 deficiency (C2D) ingested C. albicans or Saccharomyces cerevisiae at an abnormally slow rate. After preincubating C. albicans in C2D plasma, the slow rate of phagocytosis was corrected and subsequent intracellular killing of C. Albicans was normal. A normal number of C2D phagocytes reduced nitroblue tetrazolium after stimulation with either phorbol myristate acetate or ingestion of C. albicans. The rate at which chemoluminescence was generated in response to C. albicans was abnormally slow, but peak chemoluminescence produced by C2D phagocytes in response to C. albicans was normal.

C5a-induced tracheal contraction: effect of an SRS-A antagonist and inhibitors of arachidonate metabolism

C5a, a peptide derived from the fifth component of complement, has been shown to cause significant prolonged smooth muscle contraction in isolated guinea pig trachea. This contraction was not affected by the antihistamine diphenyhydramine. To assess further the potential role that C5a may play in allergic bronchospasm, we investigated the role of products of arachidonate metabolism in the C5a-induced tracheal contraction. 5,8,11,14-Eicosatetraynoic acid, an inhibitor of lipoxygenase and cyclooxygenase, virtually eliminated the tracheal contraction induced by C5a. The prostaglandin synthesis inhibitor, acetylsalicylate, did not inhibit the C5a-induced tracheal contraction and enhanced the tracheal response to acetylcholine. FPL 55712, an antagonist of slow reacting substance of anaphylaxis (SRS-A), almost completely inhibited the tracheal response to C5a and at higher concentrations employed, FPL 55712 also inhibited the tracheal response to exogenous prostaglandin F 2 alpha. These studies indicate that C5a-induced tracheal contraction is mediated by a product or products of arachidonate metabolism, and is, at least in part, mediated by SRS-A.

C5a-induced tracheal contraction: effect of an SRS-A antagonist and inhibitors of arachidonate metabolism

C5a, a peptide derived from the fifth component of complement, has been shown to cause significant prolonged smooth muscle contraction in isolated guinea pig trachea. This contraction was not affected by the antihistamine diphenyhydramine. To assess further the potential role that C5a may play in allergic bronchospasm, we investigated the role of products of arachidonate metabolism in the C5a-induced tracheal contraction. 5,8,11,14-Eicosatetraynoic acid, an inhibitor of lipoxygenase and cyclooxygenase, virtually eliminated the tracheal contraction induced by C5a. The prostaglandin synthesis inhibitor, acetylsalicylate, did not inhibit the C5a-induced tracheal contraction and enhanced the tracheal response to acetylcholine. FPL 55712, an antagonist of slow reacting substance of anaphylaxis (SRS-A), almost completely inhibited the tracheal response to C5a and at higher concentrations employed, FPL 55712 also inhibited the tracheal response to exogenous prostaglandin F 2 alpha. These studies indicate that C5a-induced tracheal contraction is mediated by a product or products of arachidonate metabolism, and is, at least in part, mediated by SRS-A.

C5a induced tracheal contraction: a histamine independent mechanism

C5a, a peptide derived from the fifth component of complement, caused significant prolonged smooth muscle contraction in isolated guinea pig trachea. Diphenhydramine, a histamine receptor antagonist of the H1 type, had no effect on either the rate, amplitude or duration of C5a induced tracheal contraction, whereas it significantly inhibited the tracheal response to exogenous histamine. Diphenhydramine also caused a significant delay in the response to compound 48/80 in normal guinea pig trachea and to antigen in actively sensitized trachea, indicating that the antihistamine was capable of inhibiting tracheal contractions to endogenously released histamine. C5a induced tracheal smooth muscle contraction was also unaffected by antagonists of H2, muscarinic cholinergic and alpha adrenergic receptors. These results indicate that C5a induced tracheal contraction is independent of histamine and is potentially a mediator of allergic bronchospasm.

C5a induced tracheal contraction: a histamine independent mechanism

C5a, a peptide derived from the fifth component of complement, caused significant prolonged smooth muscle contraction in isolated guinea pig trachea. Diphenhydramine, a histamine receptor antagonist of the H1 type, had no effect on either the rate, amplitude or duration of C5a induced tracheal contraction, whereas it significantly inhibited the tracheal response to exogenous histamine. Diphenhydramine also caused a significant delay in the response to compound 48/80 in normal guinea pig trachea and to antigen in actively sensitized trachea, indicating that the antihistamine was capable of inhibiting tracheal contractions to endogenously released histamine. C5a induced tracheal smooth muscle contraction was also unaffected by antagonists of H2, muscarinic cholinergic and alpha adrenergic receptors. These results indicate that C5a induced tracheal contraction is independent of histamine and is potentially a mediator of allergic bronchospasm.

Regional deficiency of secretory IgA in a patient with combined immunodeficiency of the ADA deficient type

The IgA system in a patient with SCID and ADA deficiency showed heterogeneity. Serum IgA and stool secretory IgA (SIgA) levels were normal, but with altered kappa/lambda and A1/A2 subclass ratios; IgA in saliva and urine was deficient. Amounts of secretory component were normal. Jejunal and rectal biopsies showed prominent lymphonodular hyperplasia, but no cells containing IgA. A normal serum IgA level therefore does not always predict an intact secretory IgA system.

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.