Vasculometabolic and Inflammatory Effects of Aldosterone in Obesity.

CONTEXT: Not all obese individuals develop cardiovascular disease (CVD). Hyperaldosteronism is suggested to cause inflammation and metabolic dysregulation, and might contribute to CVD development in obese individuals. OBJECTIVE: We aimed to investigate the association of aldosterone concentrations with inflammation, metabolic disturbances, and atherosclerosis in overweight and obese individuals. Additionally, we measured renin concentrations to investigate whether the observed effects reflected general activation of the renin-angiotensin-aldosterone system (RAAS). DESIGN: A cross-sectional cohort study (300-OB study) was conducted. Various inflammatory parameters, traits of the metabolic syndrome, lipidome and metabolome parameters, fat distribution, and carotid atherosclerosis were associated with plasma aldosterone and renin levels. SETTING: The setting of this study was the Radboudumc (i.o. Radboudumc), the Netherlands. PATIENTS: A total of 302 individuals with a body mass index greater than or equal to 27 kg/m2 participated. MAIN OUTCOME MEASURES AND RESULTS: Aldosterone was associated with various markers of inflammation and metabolic dysregulation, which partly differed from the associations observed for renin. Although both were associated with inflammatory cell numbers, only renin was associated with classical markers of systemic inflammation. Both were associated with the metabolic syndrome and hepatic steatosis. Of the traits that constitute metabolic syndrome, aldosterone, but not renin, was associated with triglyceride concentrations. Accordingly, aldosterone was associated with large very low-density lipoprotein particles; metabolomics studies further associated aldosterone with urate concentrations and derivatives of the linoleic acid metabolism pathway. Neither aldosterone nor renin was associated with atherosclerotic plaque thickness. CONCLUSIONS: Aldosterone is not an important driver of systemic inflammation in the obese, whereas aldosterone concentrations and metabolic dysregulation are strongly intertwined in these individuals. Although prospective studies are necessary to validate these results, the independent effects of aldosterone on carotid atherosclerosis appear modest.

Hyperinflammation and derangement of renin-angiotensin-aldosterone system in COVID-19: A novel hypothesis for clinically suspected hypercoagulopathy and microvascular immunothrombosis.

Early clinical evidence suggests that severe cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are frequently characterized by hyperinflammation, imbalance of renin-angiotensin-aldosterone system, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In this paper, we present an immunothrombosis model of COVID-19. We discuss the underlying pathogenesis and the interaction between multiple systems, resulting in propagation of immunothrombosis, which through investigation in the coming weeks, may lead to both an improved understanding of COVID-19 pathophysiology and identification of innovative and efficient therapeutic targets to reverse the otherwise unfavorable clinical outcome of many of these patients.

Aldosterone induced up-expression of ICAM-1 and ET-1 in pancreatic islet endothelium may associate with progression of T2D.

Previous studies have demonstrated that excess aldosterone impairs glucose metabolism. However, the underlying mechanism is still misty. Aldosterone has been proved a risk factor of fibrosis and inflammation. And the histology of islets from patients with type 2 diabetes (T2D) also displays inflammation and fibrosis. But it is unclear whether aldosterone has direct impact on islet inflammation and fibrosis in T2D. Islet endothelium plays a significant role in the maintenance of islet beta cell function and has a close relationship with islet fibrosis and inflammation. Therefore, we focused on the effect of aldosterone on the islet endothelium. In this study, we utilized a diabetic db/db mouse model and examined serum aldosterone levels, islet macrophages infiltration, and islet fibrosis. After we confirmed that there was an increased expression of intercellular cell adhesion molecule-1 (ICAM-1) and endothelin-1 (ET-1) in islet of diabetic mice compared with wild type mice. We next determined that aldosterone increased expression of ICAM-1 and ET-1 in both mRNA and protein levels in islet endothelium in vitro. And then we tested the expression of mineralocorticoid receptor (MR) in islet endothelium in vitro and in vivo. Our results showed that aldosterone can up-regulate the expression levels of ICAM-1 and ET-1 through MR. These findings suggest excess aldosterone might participate in islet inflammation and fibrosis in T2D.

Auditory closed-loop stimulation of EEG slow oscillations strengthens sleep and signs of its immune-supportive function.

Sleep is essential for health. Slow wave sleep (SWS), the deepest sleep stage hallmarked by electroencephalographic slow oscillations (SOs), appears of particular relevance here. SWS is associated with a unique endocrine milieu comprising minimum cortisol and high aldosterone, growth hormone (GH), and prolactin levels, thereby presumably fostering efficient adaptive immune responses. Yet, whether SWS causes these changes is unclear. Here we enhance SOs in men by auditory closed-loop stimulation, i.e., by delivering tones in synchrony with endogenous SOs. Stimulation intensifies the hormonal milieu characterizing SWS (mainly by further reducing cortisol and increasing aldosterone levels) and reduces T and B cell counts, likely reflecting a redistribution of these cells to lymphoid tissues. GH remains unchanged. In conclusion, closed-loop stimulation of SOs is an easy-to-use tool for probing SWS functions, and might also bear the potential to ameliorate conditions like depression and aging, where disturbed sleep coalesces with specific hormonal and immunological dysregulations.

Aldosterone Induces Renal Fibrosis and Inflammatory M1-Macrophage Subtype via Mineralocorticoid Receptor in Rats.

We aimed to evaluate macrophages heterogeneity and structural, functional and inflammatory alterations in rat kidney by aldosterone + salt administration. The effects of treatment with spironolactone on above parameters were also analyzed. Male Wistar rats received aldosterone (1 mgkg-1d-1) + 1% NaCl for 3 weeks. Half of the animals were treated with spironolactone (200 mg kg-1d-1). Systolic and diastolic blood pressures were elevated (p<0.05) in aldosterone + salt-treated rats. Relative kidney weight, collagen content, fibronectin, macrophage infiltrate, CTGF, Col I, MMP2, TNF-α, CD68, Arg2, and SGK-1 were increased (p<0.05) in aldosterone + salt-treated rats, being reduced by spironolactone (p<0.05). Increased iNOS and IFN-γ mRNA gene expression (M1 macrophage markers) was observed in aldosterone + salt rats, whereas no significant differences were observed in IL-10 and gene ArgI mRNA expression or ED2 protein content (M2 macrophage markers). All the observed changes were blocked with spironolactone treatment. Macrophage depletion with liposomal clodronate reduced macrophage influx and inflammatory M1 markers (INF-γ or iNOS), whereas interstitial fibrosis was only partially reduced after this intervention, in aldosterone plus salt-treated rats. In conclusion, aldosterone + salt administration mediates inflammatory M1 macrophage phenotype and increased fibrosis throughout mineralocorticoid receptors activation.

Modulation of Immunity and Inflammation by the Mineralocorticoid Receptor and Aldosterone.

The mineralocorticoid receptor (MR) is a ligand dependent transcription factor. MR has been traditionally associated with the control of water and electrolyte homeostasis in order to keep blood pressure through aldosterone activation. However, there is growing evidence indicating that MR expression is not restricted to vascular and renal tissues, as it can be also expressed by cells of the immune system, where it responds to stimulation or antagonism, controlling immune cell function. On the other hand, aldosterone also has been associated with proinflammatory immune effects, such as the release of proinflammatory cytokines, generating oxidative stress and inducing fibrosis. The inflammatory participation of MR and aldosterone in the cardiovascular disease suggests an association with alterations in the immune system. Hypertensive patients show higher levels of proinflammatory mediators that can be modulated by MR antagonism. Although these proinflammatory properties have been observed in other autoimmune and chronic inflammatory diseases, the cellular and molecular mechanisms that mediate these effects remain unknown. Here we review and discuss the scientific work aimed at determining the immunological role of MR and aldosterone in humans, as well as animal models.

Immunological and hemostasiological disorders in women with ovarian hyperstimulation syndrome.

To assess the markers of destabilization of homeostasis in women with ovarian hyperstimulation syndrome (OHSS), the investigation of the levels of cortisol, markers of renin-angiotensin-aldosterone system, endothelin, proinflammatory cytokines, acute phase proteins, and parameters of hemostasis was performed. Our survey involved 105 women who became pregnant after IVF: 21 women with symptoms of the early moderate and severe OHSS, 28 women with the late moderate and severe OHSS, and 56 pregnant women undergoing IVF without symptoms of OHSS. It was found significant increase of levels of cortisol, interleukins, the number of leucocytes, concentration of fibrinogen and D-dimers in patients with early and late OHSS. The development of late OHSS is associated with the lower level of IL-8 and ceruloplasmin. The OHSS is characterized by leukocytosis, higher level of IL-6, TNF-α, fibrinogen, D-dimers, thus reflecting the homeostasis imbalance. The determination of the level of fibrinogen, D-dimers, leukocytes can be an important screening test of the intensity of the inflammatory process in patients with OHSS.

Aldosterone receptor blockers spironolactone and canrenone: two multivalent drugs.

Canrenone is a derivative of spironolactone with lower antiandrogen activity. The drug is used only in few countries and can block all the side effects of aldosterone (ALDO). The drug is effective even in the presence of normal concentrations of ALDO. Mineralcorticoid receptor antagonists block the inflammatory activity of ALDO at the level of target tissues as heart, vessels and mononuclear leukocytes. Canrenone reduces the progression of insulin resistance and of microalbuminuria in type 2 diabetes and other related diseases. Both canrenone and hydrochlorothiazide can enhance the effect of treatment with ACE inhibitors and angiotensin II receptor blockers on microalbuminuria, but ALDO receptor blockers are more active. This different action is due to the fact that only canrenone blocks mineralocorticoid receptors. Serum potassium and renal function should be monitored before and during the treatment. ALDO receptor blockers are recommended in addition to polytherapy for resistant hypertension, but there are no studies on the effect of the drug as first-choice therapy.

Mineralocorticoid receptor signaling reduces numbers of circulating human naïve T cells and increases their CD62L, CCR7, and CXCR4 expression.

The role of mineralocorticoid receptors (MRs) in human T-cell migration is not yet understood. We have recently shown that the MR antagonist spironolactone selectively increases the numbers of circulating naïve and central memory T cells during early sleep, which is the time period in the 24 h cycle hallmarked by predominant MR activation. To investigate whether this effect is specific to spironolactone's blockade of MRs and to study the underlying molecular mechanisms, healthy humans were given the selective MR-agonist fludrocortisone or placebo and numbers of eight T-cell subsets and their CD62L and CXCR4 expression were analyzed. Fludrocortisone selectively reduced counts of naïve CD4(+) , central memory CD4(+), and naïve CD8(+) T cells and increased CXCR4 expression on the naïve subsets. In complementing in vitro studies, fludrocortisone enhanced CXCR4 and CD62L expression, which was counteracted by spironolactone. Incubation of naïve T cells with spironolactone alone reduced CD62L and CCR7 expression. Our results indicate a regulatory influence of MR signaling on human T-cell migration and suggest a role for endogenous aldosterone in the redistribution of T-cell subsets to lymph nodes, involving CD62L, CCR7, and CXCR4. Facilitation of T-cell homing following sleep-dependent aldosterone release might thus essentially contribute to sleep's well-known role in supporting adaptive immunity.

The renin-angiotensin-aldosterone system in pre-eclampsia: the delicate balance between good and bad.

Pregnancy demands major changes of the cardiovascular system, and this involves, among others, activation of the RAAS (renin-angiotensin-aldosterone system), allowing an aldosterone-dependent increase in volume. Remarkably, a relative resistance to the pressor response of AngII (angiotensin II) develops simultaneously to prevent the increase in blood pressure that would normally accompany RAAS activation. The increase in volume, the degree of RAAS activation and the diminished pressor response to AngII are less pronounced in pre-eclampsia. However, animal models displaying excessive RAAS activation also result in a pre-eclampsia-like syndrome, and the aldosterone/renin ratio is elevated in pre-eclampsia compared with a normal pregnancy. New insights into the pathogenesis of pre-eclampsia have revealed a major role for VEGF (vascular endothelial growth factor), VEGF-inactivating sFlt-1 (soluble fms-like tyrosine kinase-1) and AT1 (angiotensin II type 1) receptor autoantibodies. The last mentioned activate AT(1) receptors, thereby potentially suppressing circulating renin and aldosterone. VEGF, both directly and indirectly (by increasing capillary density), affects adrenal aldosterone synthesis. The present review summarizes all of the recent findings regarding RAAS regulation in pre-eclampsia compared with normal pregnancy, concluding that factors such as sFlt-1 and AT(1) receptor autoantibodies disturb the delicate balance that normally results in a volume increase and a diminished vasoconstrictor response to AngII in pregnant women. It is possible that there are non-parallel changes in the circulating and renal RAAS in pre-eclampsia, which are potentially reflected by the urinary levels of renin.

The mineralocorticoid receptor-p38MAPK-NFκB or ERK-Sp1 signal pathways mediate aldosterone-stimulated inflammatory and profibrotic responses in rat vascular smooth muscle cells.

AIM: To explore the signalling pathways involved in aldosterone-induced inflammation and fibrosis in rat vascular smooth muscle cells (VSMCs). METHODS: Using Western blotting and real-time RT-PCR, we investigated the effects of aldosterone on the expression of cyclooxygenase-2 (Cox-2) and IL-6, two important proinflammatory factors, and TGFß1, a critical profibrotic factor, in VSMCs. RESULTS: Aldosterone treatment significantly increased the expression of Cox-2 and IL-6 and activation of p38MAPK and NF-κB. The expression of both Cox-2 and IL-6 could be blocked by the mineralocorticoid receptor (MR) antagonist spironolactone and the p38MAPK inhibitor SB203580. Also, the rapid phosphorylation of p38MAPK could be suppressed by SB203580 but not by spironolactone, implicating in nongenomic effects of aldosterone. Similar to SB203580 and spironolactone, the NF-κB inhibitor α-p-tosyl-L-lysine chloromethyl ketone (TLCK) markedly attenuated expression of Cox-2, indicating that MR, p38MAPK and NF-κB are associated with aldosterone-induced inflammatory responses. Furthermore, aldosterone enhanced expression of TGFß1 in rat VSMCs. This result may be related to activation of the MR/ERK-Sp1 signalling pathway because PD98059, an ERK1/2 inhibitor, significantly blocked the rapid phosphorylation of ERK1/2 and function of Sp1 and led to reduced expression of TGFß1. Spironolactone was also shown to significantly inhibit TGFß1 and Sp1 expression but not ERK1/2 phosphorylation. CONCLUSION: These results suggest that aldosterone-induced inflammatory responses and fibrotic responses may be mediated by the MR/p38MAPK-NF-κB pathways and the MR/ERK-Sp1 pathways in VSMCs, respectively.

Inflammation in hypertension: current therapeutic approaches.

The role of inflammation as crucial underlying process contributing to the initiation and the progression of atherosclerosis as well as its clinical manifestations is well established. Recent data have demonstrated also a strong association between essential hypertension and inflammatory process. In addition, several studies have shown that tissue expression and plasma concentrations of several inflammatory biomarkers/mediators are related to increased risk of hypertension. The determination of markers such as acute phase proteins (C-reactive protein), adhesion molecules such as vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and chemokines is crucial in determining therapeutic responses and clinical outcomes of hypertensive patients. In addition, several therapeutic approaches targeting blood pressure may have also beneficial effects in terms of inflammation and thus further clinical benefits. Although the available data are encouraging, further large scale studies are required to evaluate the reported anti-inflammatory effects in management and treatment of arterial hypertension.

The clinical utility of two renin mass methods to detect primary hyperaldosteronism compared with renin activity.

BACKGROUND: Primary hyperaldosteronism (PHA) is characterized by a raised plasma aldosterone concentration (PAC) with suppressed plasma renin activity (PRA). We evaluated two renin mass methods for PHA detection compared with the PAC:PRA ratio. METHODS: Samples from patients attending a specialist hypertensive clinic were analysed by Liaison automated chemiluminescent immunoassay and Diagnostic Systems Laboratories (DSL) immunoradiometric assay (IRMA) for renin mass; I(-125) radioimmunoassay of angiotensin I generated from endogenous angiotensinogen for PRA; Siemens Coat-a-count radioimmunoassay for PAC. Subjects included those on ß-blockers which suppress renin, causing an equivalent biochemical picture to PHA. Aldosterone/renin ratios (ARR) were calculated for PRA, DSL and Liaison methods. The first 100 subjects were used to identify cut-off ratios ensuring maximum specificity at 100% sensitivity for PHA detection. This cut-off was retested in a subsequent population (n = 43). RESULTS: A Liaison renin of 5 ng/L separated PRAs of ≤0.5 from ≥0.6 pmol/mL/h. The DSL method had greater scatter. In population 1 (18 PHA), cut-off ratios of >118 pmol/ng (Liaison) and >60 pmol/ng (DSL) gave specificities of 58.5% and 61%, respectively, with 100% sensitivity. If criteria for PHA included PAC ≥350 pmol/L and excluded ß-blocked subjects, specificity increased to 95.1% and 90% for Liaison and DSL, respectively. In population 2 (6 PHA), specificities for Liaison and DSL ARRs were 86.4% and 78.3%. Using the ratio with PAC and ß-blocker criteria, specificities for Liaison and DSL were 97.3% and 86.5%, respectively. CONCLUSIONS: The Liaison ARR used with PAC and ß-blocker criteria provided an automatable alternative to identify the same patients as the PAC:PRA ratio.

A microsphere-based duplex competitive immunoassay for the simultaneous measurements of aldosterone and testosterone in small sample volumes: validation in human and mouse plasma.

BACKGROUND: The small blood volumes available in rodent studies often limit adequate quantification of all hormones of interest. We report here the development of two new assays combining an extraction step with multiplex immunoassay (MIA) technology for the simultaneous determination of aldosterone and testosterone in 50 µl sample volume. METHODS: Following solvent extraction, aldosterone and testosterone competitive immunoassays are performed incorporating biotinylated tracers and antibody-coated beads each having a unique fluorescence. Quantification is via addition of streptavidin-R-phycoerythrin (SA-PE). The assays were validated and compared to established methods. Baseline hormone levels in mice from four different strains, and changes after ACTH and HCG stimulation in CD-1 mice are shown. RESULTS: The assays are sensitive (aldosterone 15 pg/ml, testosterone 12 pg/ml), reproducible (intra-/inter-assay imprecision aldosterone 5.1-15.6%/9.9-15.8% and testosterone 9.7-10.9%/7.7-11.4%) and correlate significantly to established assays (r=0.94-0.95). Baseline aldosterone levels varied between strains, but not between the genders. Testosterone was significantly higher in male of all strains except in C57BL/6 × NMRI mice. After ACTH injection, aldosterone (median, interquartile range) rose from 354 (261-396) pg/ml to 2008 (875-2467) in male and from 260 (210-576) to 1120 (734-1528) in female CD-1 mice. HCG injection in the same strain increased testosterone in male mice only (3.5 (0.4-8.3) ng/ml to 31.8 (30.4-33.9) ng/ml, P<0.01). CONCLUSIONS: We describe a MIA for the simultaneous measurement of aldosterone and testosterone in small volumes after extraction. In addition to presenting a new tool for steroid research in rodent models, our data show strain-dependent differences in steroid hormone metabolism in rodents.

Aldosterone promotes autoimmune damage by enhancing Th17-mediated immunity.

Excessive production of aldosterone leads to the development of hypertension and cardiovascular disease by generating an inflammatory state that can be promoted by T cell immunity. Because nature and intensity of T cell responses is controlled by dendritic cells (DCs), it is important to evaluate whether the function of these cells can be modulated by aldosterone. In this study we show that aldosterone augmented the activation of CD8(+) T cells in a DC-dependent fashion. Consistently, the mineralocorticoid receptor was expressed by DCs, which showed activation of MAPK pathway and secreted IL-6 and TGF-beta in response to aldosterone. In addition, DCs stimulated with aldosterone impose a Th17 phenotype to CD4(+) T cells, which have recently been associated with the promotion of inflammatory and autoimmune diseases. Accordingly, we observed that aldosterone enhances the progression of experimental autoimmune encephalomyelitis, an autoimmune disease promoted by Th17 cells. In addition, blockade of the mineralocorticoid receptor prevented all aldosterone effects on DCs and attenuated experimental autoimmune encephalomyelitis development in aldosterone-treated mice. Our data suggest that modulation of DC function by aldosterone enhances CD8(+) T cell activation and promotes Th17-polarized immune responses, which might contribute to the inflammatory damage leading to hypertension and cardiovascular disease.

ANG II-induced cardiac molecular and cellular events: role of aldosterone.

Chronic elevation of circulating ANG II is associated with cardiac remodeling in patients with hypertension and heart failure. The underlying mechanisms, however, are not completely defined. Herein, we studied ANG II-induced molecular and cellular events in the rat heart as well as their links to the redox state. We also addressed the potential contribution of aldosterone (ALDO) on ANG II-induced cardiac remodeling. In ANG II-treated rats, and compared with controls, we found: 1) the expression of proinflammatory/profibrogenic mediators was significantly increased in the perivascular space and at the sites of microscopic injury in both ventricles; 2) macrophages and myofibroblasts were primary repairing cells at these sites, together with increased fibrillar collagen volume; 3) apoptotic macrophages and myofibroblasts were evident at the same sites; 4) NADPH oxidase (gp91phox) was significantly enhanced at these regions and primarily expressed by macrophages, whereas superoxide dismutase and catalase levels remained unchanged; 5) plasma 8-isoprostane levels were significantly increased; and 6) blood pressure was significantly elevated. Losartan treatment completely prevented cardiac oxidative stress as well as molecular/cellular responses and normalized blood pressure. Spironolactone treatment partially suppressed the cardiac inflammatory/fibrogenic responses and redox state. Thus chronic elevation of circulating ANG II is accompanied by a proinflammatory/profibrogenic phenotype involving vascular and myocardial remodeling in both ventricles. Enhanced reactive oxygen species production at these sites and increased plasma 8-isoprostane indicate the involvement of oxidative stress in ANG II-induced cardiac injury. ALDO contributes, in part, to ANG II-induced cardiac molecular and cellular responses.

Participation of aldosterone in the vascular inflammatory response of spontaneously hypertensive rats: role of the NFkappaB/IkappaB system.

OBJECTIVE: To investigate the participation of aldosterone in the vascular inflammatory process associated with hypertension, as well as the possible involvement of the NFkappaB/IkappaB system. METHODS: Male spontaneously hypertensive rats (SHR; 20-22 weeks old) untreated or treated with either the aldosterone receptor antagonist, eplerenone (100 mg/kg per day) or triple antihypertensive therapy (HHR: hydralazine + hydrochlorothiazide + reserpine; 20 + 7 + 0.15 mg/kg per day) were used in the study. Wistar-Kyoto rats (WKY) were used as a normotensive reference group. Aortic mRNA expression and plasma levels of interleukin (IL)-1beta, IL-6 and tumour necrosis factor alpha (TNFalpha) were measured. Likewise, the aortic expression of the nuclear factor kappaB (NFkappaB) p50 subunit precursor, p105, and its inhibitor (IkappaB) were measured. RESULTS: SHR showed higher aortic expression of IL-1beta, IL-6 and TNFalpha than WKY (P < 0.05) and higher plasma levels of IL-1beta and IL-6 than WKY (P < 0.05). Moreover, SHR also presented increased aortic expression of nuclear transcription factor NFkappaB p50 subunit precursor (p105), and a reduction of its inhibitor IkappaB. Both eplerenone and HHR decreased blood pressure to a comparable extent (P < 0.05). This effect was accompanied by a reduction in plasma levels of IL-1beta and IL-6 and aortic mRNA expression of IL-1beta, IL-6 and TNFalpha. However, the effect of eplerenone was more marked, since eplerenone-treated rats showed significantly lower inflammatory parameters than SHR receiving HHR. In addition, both antihypertensive treatments increased IkappaB mRNA expression in a similar manner, but only eplerenone reduced NFkappaB mRNA expression. CONCLUSIONS: Aldosterone, as well as an increase in haemodynamic forces produced by hypertension, participate in the vascular inflammatory process associated with hypertension in SHR. This effect seems to be mediated by enhanced vascular expression of cytokines through a modification of the NFkappaB/IkappaB system.

Generating recombinant anti-idiotypic antibodies for the detection of haptens in solution.

A new method is described for generating recombinant human and chicken antibody fragments for accurate quantification of haptens in solution. The chemistry of labelling small molecules has always been a problem in the development of immunoassays. Here, we describe a specific panning procedure that enables the selection of recombinant anti-idiotypic phage antibodies that bind to hapten binding molecules (e.g., antibodies) in the absence of the hapten, but are displaced in a highly specific and concentration dependent manner, in the presence of the hapten. The major advantage of such a detection system is that there is no need to label the hapten or to covalently attach it to a solid phase. In this study we demonstrate, using cortisol and aldosterone as model haptens, that the recombinant antibody phage display technology offers great possibilities to generate recombinant anti-idiotypic antibodies. Furthermore, we show that such antibodies can be used successfully to design highly sensitive immunoassays for the quantification of small molecules.

Influence of viscosity and ionic strength on the reaction kinetics of aldosterone and androstendione and their specific antibodies.

This paper analyses the influence of viscosity and ionic strength on the kinetics and equilibrium of the reactions of (125)I labelled androstendione and aldosterone with their specific antibodies used in the radioactive immunoassay determination of such hormones. Bi-exponential and irreversible kinetics is found for androstendione, and single-exponential and reversible ones for aldosterone. The results of the viscosity analysis reflect clear negative influence on direct reaction rate. Ionic strength excerpts some influence but not in a significant way, which suggests that the variation resulting from the effect of the glycerol addition is not due to the influence of the dielectric constant of the solutions used. The apparent product of the electrical charges is 0.228 for aldosterone, and 0.230 and -0.230 for androstendione. Results show diffusive control for both cases.