The relationship between serum or plasma levels of tumor necrosis factor alpha and neuropsychological functioning in early human immunodeficiency virus infection.
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AIDS Dementia Complex↗
Biomedical subjects
J M Zeller
Publications and source records attributed to J M Zeller.
C-reactive protein selectively enhances the intracellular generation of reactive oxygen products by IgG-stimulated monocytes and neutrophils.
The acute phase protein, C-reactive protein (CRP), when heat-aggregated (Agg-CRP), potentiates immunoglobulin G (IgG) Fc receptor-mediated luminol-enhanced chemiluminescence (CL) in human monocytes and neutrophils. Luminol-CL is a sensitive measure of phagocyte respiratory burst activity; however, the nature of oxidative products contributing to the light emission and their site of generation remain incompletely defined. To more precisely describe the oxidative burst of monocytes and neutrophils to Agg-CRP, superoxide anion release was measured by cytochrome c reduction. In addition, the extracellular release of hydrogen peroxide was distinguished from hydrogen peroxide generation using a phenol red oxidation assay. Finally, a flow cytometric determination of dichlorofluorescein (DCFH) oxidation was employed as an index of intracellular peroxide production. Although Agg-CRP alone did not stimulate hydrogen peroxide generation by either monocytes or neutrophils, it significantly enhanced hydrogen peroxide generation in response to heat-aggregated IgG (Agg-IgG). In contrast, Agg-CRP did not enhance the extracellular release of either hydrogen peroxide or superoxide anion from Agg-IgG-stimulated cells. The capacity of Agg-CRP to enhance selectively intracellular oxidative product generation was confirmed when measuring DCFH oxidation in Agg-IgG-stimulated cells. To evaluate whether this selective enhancement of intracellular oxidative events could be attributed, at least in part, to a scavenging effect of Agg-CRP, a cell-free oxygen radical-generating system was employed. Agg-CRP did not significantly diminish the lucigenin-amplified CL response induced by the xanthine/xanthine oxidase reaction. These results indicate that although Agg-CRP enhances the intracellular generation of reactive oxygen intermediates by monocytes and neutrophils, extracellular release of those products is not influenced by cell interaction with Agg-CRP. It is tempting to speculate that CRP can selectively boost the microbicidal activities of monocytes and neutrophils within an inflammatory site by amplifying the intracellular generation of reactive oxygen products without increasing damage to surrounding normal tissues.
Acridines↗
Cognitive changes associated with the acquired immunodeficiency syndrome.
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Adult↗
Nutritional alterations in persons with HIV infection.
Potential relationships among nutritional status, immune function and quality of life were examined in a convenience sample of 40 outpatient homosexual and bisexual males stratified into five categories, using modified Walter Reed Staging Criteria. Nutritional status was assessed by measuring height, weight, triceps skinfold thickness, arm circumference, nutrient intake and serum albumin. Immune status was evaluated by determining T-helper cell numbers and percentages. The Quality of Life test was used to obtain information about life quality. Nutritional assessment failed to show significant differences among groups with the exception that serum albumin levels were reduced in persons with AIDS. The significance of change in serum albumin in regard to nutritional status is unclear, since serum albumin is affected by a number of non-nutritional factors, such as hydration status and liver function. The study also revealed a significant decline in T-helper percentages, but not absolute T-helper cell numbers as a function of disease stage. There were no statistically significant differences between the quality of life scores with respect to each grouping. These data suggest that asymptomatic patients as well as those with ARC or stable AIDS are able to maintain body weight and composition.
AIDS-Related Complex↗
Detecting subtle cognitive changes in patients infected with the human immunodeficiency virus.
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Biomarkers↗
Binding sites for C-reactive protein on human monocytes are distinct from IgG Fc receptors.
Previous investigations have provided evidence to suggest that C-reactive protein (CRP), an acute-phase reactant, binds to human monocytes at a membrane site that is either identical to or physically associated with IgG Fc receptors. To characterize further the relationship between monocyte CRP binding sites and IgG Fc receptors, monocytes were allowed to attach to surfaces coated with IgG or CRP and binding-site redistribution was assessed. Binding was measured by using protein-coated sheep erythrocytes (E). When attached to control (gelatin or albumin) surfaces, greater than 60% and 43% of monocytes formed rosettes with E-IgG and E-CRP, respectively. Following adherence to surface immobilized CRP, the proportion of cells binding E-IgG was unchanged; however, fewer than 20% of monocytes bound E-CRP. When attached to IgG-coated surfaces, fewer than 20% of monocytes formed rosettes with either E-IgG or E-CRP. In order to determine whether the unidirectional modulation of CRP and IgG binding sites was the result of CRP binding directly to a subclass of IgG Fc receptors, fluid-phase IgG-blocking studies were performed. When monocyte monolayers were preincubated with either monomeric or heat-aggregated IgG, a dose-dependent reduction in E-IgG binding was observed. In contrast, all concentrations of fluid-phase IgG failed to inhibit monocyte binding of E-CRP. These data indicate that CRP binds to human monocytes at a site physically associated with but distinct from IgG Fc receptors.
Antigens, Differentiation↗
Evaluation of human monocyte oxidative metabolism utilizing a flow cytometric assay.
Assays routinely employed to evaluate human monocyte respiratory burst activation have been limited to measuring responses of bulk cell preparations. We demonstrate that individual monocyte responses can be easily assessed by using 2',5' dichlorofluorescin diacetate (DCFH-DA) and flow cytometry. Adherence purified monocytes were incubated with DCFH-DA, washed, and stimulated with either phorbol myristate acetate (PMA) or heat-aggregated IgG (HAIgG). Log green fluorescence signals were measured by using a flow cytometer equipped with a 5-W argon laser set at an excitation wavelength of 488 nm. Optimal conditions for stimulation included exposure to 5 microM concentrations of DCFH-DA for 15 min, followed by a 60-min incubation with either PMA or HAIgG. Dichlorofluorescin (DCFH) oxidation by monocytes increased in a graded fashion as a function of stimulus concentration. Monocytes responded as a uniform population in response to increasing doses of PMA and HAIgG. This oxidative response was also monitored in mixed populations of mononuclear leukocytes, with monocytes identified on the basis of light scatter properties and surface antigen staining with anti-CD14. More than 90% of cells demonstrating increases in log green fluorescence signals following activation were CD14 positive. Measurement of DCFH oxidation by monocytes is reflective of the capacity to undergo a respiratory burst response, in that monocytes obtained from patients with chronic granulomatous disease were only minimally reactive. This assay, representing a rapid means of assessing monocyte respiratory burst activation by single cell analysis, is suitable for use in both clinical and research settings.
Flow Cytometry↗
Changes in respiratory burst activity during human monocyte differentiation in suspension culture.
Monocytes undergo a process of differentiation following their accumulation into extravascular spaces. This process has been examined previously by culturing monocytes and identifying changes in cell morphology, metabolism, and function over time. The present study was designed to characterize mononuclear phagocyte respiratory burst activity as related to differentiation by measuring chemiluminescence and superoxide anion generation in cultured human monocytes. Monocytes maintained in Teflon vials for up to 12 days increased in size, were positive for nonspecific esterase, and retained the ability to ingest latex particles. During culture, however, cells progressively lost their peroxidase-positive granules. When monocytes were cultured for one or five days, they elicited less than 50% of the luminol-enhanced chemiluminescence produced by fresh monocytes following PMA stimulation. By day 7, less than 20% of day 0 PMA-elicited chemiluminescence was observed. A comparable loss of serum-opsonized zymosan-induced chemiluminescence occurred during monocyte culture. Since it is recognized that luminol-enhanced chemiluminescence is, in large part, dependent upon myeloperoxidase and since differentiated mononuclear phagocytes are only minimally peroxidase-positive, cultured monocyte respiratory burst activity was also assessed by directly quantifying superoxide anion generation. When monocytes were cultured for three or five days, they elicited 38% more superoxide anion than did fresh monocytes following PMA stimulation. At day 7, PMA-induced superoxide anion release was comparable to day 0 levels. These data indicate that monocytes allowed to differentiate under nonadherent conditions maintain the ability to undergo a respiratory burst response as measured by superoxide anion release, but they concomitantly lose peroxidase-dependent luminol-enhanced chemiluminescence. In this regard, monocytes cultured in suspension metabolically resemble macrophages that have undergone differentiation within sites of inflammation.
Cell Differentiation↗
Stimulation of human neutrophils, monocytes, and platelets by modified C-reactive protein (CRP) expressing a neoantigenic specificity.
C-reactive protein (CRP) can be structurally modified by heat, acid, or urea-chelation to express a neoantigen designated by us as neo-CRP. This antigen is also expressed on the in vitro primary protein translation products of both human and rabbit CRP. Unmodified CRP and CRP complexed with pneumococcal C-polysaccharide (CPS) do not express neo-CRP. Forms of CRP expressing neo-CRP but not native CRP antigenicity (even in the presence of CPS) consistently and in a dose-dependent manner potentiated the respiratory burst response of human polymorphonuclear leukocytes and peripheral blood monocytes to heat-modified IgG. Forms of CRP expressing neo-CRP antigenicity also induced reactions of aggregation and secretion from isolated platelets and potentiated platelet activation stimulated by ADP in platelet-rich-plasma, while native CRP alone or complexed with CPS again did not. Unlike CRP-CPS complexes, forms of CRP expressing neo-CRP were not able to activate the complement system. These data emphasize the biologic potential inherent in this humoral acute-phase reactant, particularly in the activation of the formed elements of the blood important in the inflammatory response. Since these cell-activating properties are preferentially observed when CRP is structurally modified to express the neo-CRP antigen, such a molecular conversion may be central to the structure-function relationships of CRP at local sites of inflammation and tissue injury.
Blood Platelets↗
Enhancement of human monocyte and peritoneal macrophage chemiluminescence activities in women with endometriosis.
Preliminary reports indicate that products of human mononuclear phagocytes may contribute to the infertility associated with endometriosis. To determine whether the generation of reactive oxygen metabolites by blood monocytes and peritoneal macrophages is altered in women with endometriosis, the present study evaluated luminol-enhanced chemiluminescence (CL) in cells at rest and following stimulation with phorbol myristate acetate (PMA) or serum-opsonized zymosan (SOZ). Peripheral venous blood and peritoneal fluid samples were collected from 60 infertile women undergoing diagnostic laparoscopy at midluteal phase and mononuclear phagocytic cell fractions were obtained by density gradient centrifugation. Whereas there was no significant difference between resting CL values in peripheral blood monocytes collected from women with and without endometriosis, PMA- and SOZ-stimulated monocyte CL was significantly greater in endometriosis patients. In contrast, there was a significant elevation in resting CL values when peritoneal macrophages from endometriosis patients were compared with macrophages obtained from patients with normal pelvic organs. It appears that chronic stimulation of macrophages in the peritoneal cavity provokes constitutive release of large quantities of reactive oxygen products in women with endometriosis. This may occur secondary to the accumulation of activated monocytes into the peritoneal cavity.
Adult↗
Enhancement of human peripheral blood monocyte respiratory burst activity by aggregated C-reactive protein.
We had previously demonstrated that C-reactive protein (CRP), an acute phase reactant, when aggregated or coupled to a ligand, interacts with monocytes and certain human peripheral blood lymphocytes. The purpose of the present study, after further characterizing the binding interaction of CRP with human monocytes, was to focus on the biological response of monocytes to CRP binding. Flow cytometric analysis of human mononuclear leukocytes, following incubation with fluoresceinated heat-aggregated CRP (Agg-CRP), revealed that while greater than 70% of monocytes bound Agg-CRP, only 8% of lymphocytes demonstrated positive fluorescence. Furthermore, mean channel fluorescence values indicated that monocytes bound greater amounts of Agg-CRP per cell than did lymphocytes. Luminol-enhanced chemiluminescence (CL) was used as a measure of monocyte respiratory burst activity. Monocytes were stimulated only minimally by Agg-CRP alone; however, Agg-CRP substantially enhanced the CL response to heat-aggregated IgG. This Agg-CRP enhancing effect was selective for IgG-initiated monocyte activation, as no augmentation in CL was observed following cell stimulation with phorbol myristate acetate or serum-opsonized zymosan. These results demonstrate that aggregated CRP binds to the major proportion of human monocytes and selectively augments Fc receptor-mediated stimulation of monocyte oxidative metabolism.
C-Reactive Protein↗
Aggregated C-reactive protein binds to human polymorphonuclear leukocytes and potentiates Fc receptor-mediated chemiluminescence.
Aggregated C-reactive protein (CRP), an acute phase reactant, binds to and influences the functional activities of human mononuclear leukocytes. Our purpose was to examine the potential interactions between CRP and human polymorphonuclear leukocytes (PMNL). Binding of CRP to PMNL was examined by flow cytometry after cell incubation with fluorescein-labeled heat-aggregated CRP (Agg-CRP) or Agg-CRP and fluorescein-conjugated F(ab')2 anti-CRP antibodies. It was determined that, at an optimal dose of Agg-CRP (100 micrograms), approximately 36% of PMNL were fluorescence positive. This was in contrast to the 70% of monocytes and 8% of lymphocytes that expressed Agg-CRP binding sites. Although less than half of resting PMNL bound Agg-CRP, up to 93% of PMNL activated with 1.0 micrograms/ml of phorbol myristate acetate (PMA) expressed binding sites for Agg-CRP. Exposure to PMA similarly enhanced the amount of Agg-CRP bound per PMNL as determined by mean channel fluorescence. To evaluate whether Agg-CRP binding to PMNL could induce or modify a biologic response, respiratory burst activity was assessed by measuring luminol-enhanced chemiluminescence. Whereas Agg-CRP alone did not elicit a chemiluminescence response, Agg-CRP synergistically enhanced the chemiluminescence response induced by heat-aggregated IgG (Agg-IgG). Although this enhancing effect of Agg-CRP could be observed at both optimal and suboptimal concentrations of Agg-IgG, no enhancement of PMA or serum-opsonized zymosan-induced CL was detected. These data demonstrate that aggregated CRP binds to and selectively modulates the response of PMNL to Fc receptor-mediated activation.
C-Reactive Protein↗
Immunoglobulin G-induced single ionic channels in human alveolar macrophage membranes.
While it is well known that the engagement of IgG Fc receptors on the macrophage surface triggers a number of cellular responses, including particle ingestion, secretion, and respiratory burst activity, the mechanism of signal transmission following ligand binding remains poorly understood. To acquire more data in this area, we studied the electrical properties of the macrophage membrane and its response to oligomeric immunoglobulin G (IgG) using the patch-clamp technique on human alveolar macrophages that were obtained by bronchoalveolar lavage and maintained in short-term tissue culture. The results showed that cell resting potentials, as determined from whole-cell tight seal recordings, increased from -15 mV on the day of plating to -56 mV after the first day in culture and remained stable at this hyperpolarized level. Macrophages revealed an input resistance of 3.3 G omega, independent of age in culture. Extracellular application of heat-aggregated human IgG to cells voltage-clamped at -70 mV resulted in peak inward currents of approximately 470 pA. We identified an IgG-dependent, nonselective channel in both cell-attached and isolated membrane patches, with a unitary conductance of approximately 350 pS and a predominant subconductance level of 235 pS in symmetrical NaCl solutions. Single channel open times were observed to be in the range of seconds and, in addition, were dependent upon membrane voltage. Channel opening involved transitions between a number of kinetic states and subconductance levels. Channel events recorded in cell-attached patches showed characteristic exponential relaxations, which implied a variation in membrane potential as a result of a single ion channel opening. These data suggest that the IgG-dependent nonselective cation channel that we have characterized may provide the link between Fc receptor engagement and subsequent cellular activation.
Adult↗
Functional resistance of inflammatory macrophages to methotrexate in vitro.
The purpose of this study was to evaluate the effects of high and low therapeutic doses of methotrexate (MTX) on macrophage metabolism and function in vitro. Monolayers of elicited rat peritoneal macrophages (PM) were exposed to a wide range of MTX concentrations (10(-8) M-10(-3) M) for 24 or 48 hr and macrophage RNA and protein metabolism were evaluated by the incorporation of [3H]5-uridine and [14C]1-leucine, respectively, into trichloroacetic acid (TCA)-precipitable material. Macrophage functional activity was examined by measuring the uptake of [14C]Pseudomonas aeruginosa to assess phagocytosis and the release of 51Cr from antibody-coated [51Cr]sheep red blood cells (SRBC) to assess antibody-dependent cell-mediated cytotoxicity. Following a 24-hr incubation with 10(-3) M MTX, incorporation of [3H]5-uridine into PM monolayers was enhanced 79% when compared to control monolayers (p less than 0.005). Washout studies revealed that the stimulation of uridine incorporation was no longer observed by 24 hr following the removal of MTX from the culture medium. Incubation with 10(-3) M MTX for 48 hr returned uridine incorporation to control levels, although leucine incorporation into protein was reduced by 22% (p less than 0.01). The depression in leucine incorporation in the presence of 10(-3) M MTX was not reversed after the removal of MTX from the culture medium. Uptake of [14C]P. aeruginosa was not altered following a 24- or 48-hr incubation with either 10(-7) M or 10(-3) M MTX. Similarly, [51Cr]SRBC cytolysis was not affected by a 2-hr preincubation with and continuous exposure to between 10(-8) M and 10(-3) M MTX. These results demonstrate that incubation of inflammatory macrophages with clinically high doses of MTX can alter macrophage RNA and protein metabolism without producing demonstrable changes in macrophage functional activity.
Animals↗
Effects of high-dose methotrexate on rat alveolar and inflammatory macrophage populations.
Methotrexate (MTX) is used clinically in high doses to treat a variety of neoplastic diseases. Although it has been recognized that such aggressive chemotherapy can result in suppression of cellular host defense mechanisms, phagocytic cell function during MTX therapy remains poorly understood. The present study was designed to examine the effects of a single high dose of MTX on alveolar and inflammatory peritoneal cell populations in the rat. Male Sprague-Dawley rats were treated with a single intraperitoneal injection of MTX (25 or 50 mg/kg) and subsequent alterations in the composition of peripheral blood white cells (WBC), a peritoneal inflammatory exudate, and the resident alveolar macrophage (AM) were measured 1-4 days after MTX treatment. A severe depression in the polymorphonuclear leukocyte (PMNL) and monocyte populations in the peripheral blood was observed 72 and 96 h after either dose of MTX. Similarly, the total number of peritoneal exudate cells, collected 72 h after a caseinate inflammatory stimulus, was reduced by 50% after MTX treatment. When the cellular composition of the peritoneal exudate was examined, it was observed that macrophage and lymphocyte numbers were selectively depressed. In addition, the number of AM obtained by lung lavage was significantly reduced 72 and 96 h after MTX injection. Although both peritoneal and alveolar macrophage numbers were diminished, in vitro phagocytic activity was not impaired 72 h after MTX injection. These studies demonstrate that a single, clinically relevant dose of MTX, in addition to depressing PMNL and monocyte levels in the peripheral blood, can also impair the accumulation of macrophages at a site of tissue injury and the influx of macrophages into lung alveoli. These findings suggest that the capacity of the mononuclear phagocyte system to respond to an infectious or tumor cell challenge may be severely compromised during MTX treatment.
Animals↗
Surgical implants. Physiological response.
Following the surgical insertion of all prosthetic implants, an identical sequence of events occurs, although the magnitude of each response is variable. Initially, to maintain hemostasis, the coagulation system is stimulated and platelet activation occurs. Within minutes, leukocytes accumulate in an attempt to neutralize the foreign body. Although these phagocytic cells are generally unsuccessful at breaking down the biomaterials comprising an implant, macrophages coalesce and wall-off the foreign body from surrounding tissues. Once the inflammatory response is quiescent, fibroblasts invade the granuloma, lay down connective tissue and contract to minimize the volume occupied by the implant. Although most implant patients experience uneventful recoveries, complications resulting from chronic activation of the inflammatory response or the mechanisms involved in maintaining hemostasis can occur.
Breast↗
Modulation of inflammatory peritoneal cell function and metabolism by methotrexate.
Methotrexate (MTX) is widely used in cancer chemotherapy, although the effects of MTX on cellular antitumor defense mechanisms are poorly understood. To evaluate the effect of MTX on the cellular inflammatory response, male Sprague-Dawley rats were treated with four daily i.p. injections of MTX or a control vehicle. Rats treated with daily doses of 1.2 mg/kg MTX demonstrated a significant reduction in number of peritoneal exudate cells, specifically macrophages, collected 96 hours following the inflammatory stimulus. To determine if metabolic perturbations also occur upon exposure to MTX, glucose oxidation and protein synthesis by inflammatory cells were monitored in vitro. At a MTX concentration of 10(-3)M, peritoneal exudate cell 14C-1-glucose and 14C-6-glucose oxidation was significantly depressed. 14C-1-leucine incorporation into TCA precipitable protein was inhibited at 4 x 10(-3)M MTX. Peritoneal exudate cell viability was not altered at these concentrations of MTX. These results demonstrate that MTX, at therapeutic concentrations, can depress the influx of macrophages to a inflammatory site and also diminish energy metabolism and protein synthesis by inflammatory cells.
Acute Disease↗