Biomedical subjects

R A Erger

Publications and source records attributed to R A Erger.

7 recordsLinked to original sources

PubMed1996

Eosinophil migration in response to three molecular species of platelet activating factor.

Multiple molecular species of the eosinophil chemoattractant platelet activating factor (PAF) are produced as a result of inflammatory processes. We therefore compared the ability of three naturally occurring PAF species (C16:0, C18:0, and C18:1), which only varied at carbon 1, to induce eosinophil chemotaxis through naked 3-microns pore polycarbonate filters. Timecourse experiments indicated that all species of PAF tested induced significant and equivalent eosinophil migration at 1 h which peaked at 2 h. Overall, the rank order of chemotactic potency for the PAF species was relatively equivalent. The specific PAF antagonist WEB 2086 inhibited eosinophil migration induced by all three PAF species equally. We conclude that the degree of PAF-induced eosinophil migration is not dependent upon the molecular species of PAF.

Adult↗

PubMed1995

Interleukin-8 is a potent mediator of eosinophil chemotaxis through endothelium and epithelium.

Interleukin-8 (IL-8), a potent pro-inflammatory cytokine, has been shown to have chemotactic activity for neutrophils, lymphocytes, and basophils. Effects of IL-8 on eosinophil chemotaxis are unresolved. Because eosinophils accumulate at the site of allergic inflammation and may play a role in the pathogenesis of asthma, we investigated the eosinophilotactic capacity of IL-8. We examined the ability of IL-8 to induce human eosinophil migration across 3-microns pore naked filters, and human umbilical vein endothelial cell and human pulmonary type II-like epithelial cell (A549) monolayers cultured on these filters. IL-8 induced similar dose-related eosinophil migration through all three barriers. Kinetic experiments indicated more rapid migration through noncellular barriers but equivalent migration through all barriers by 3 h. Chemotactic/chemokinetic data show that IL-8-induced eosinophil migration is chemotactic. We also determined that the ability of IL-8 to induce transcellular migration was unique in comparison with other cytokines and was not dependent on the use of fresh vs. passaged monolayer cells as barriers. Therefore our data indicate that IL-8 may play a significant role in tissue eosinophilia observed in allergic respiratory diseases.

Antibodies↗

PubMed1995

Comparative studies indicate that platelet-activating factor is a relatively weak eosinophilotactic mediator.

Eosinophils are important immune effector cells in a variety of allergic responses and inflammatory lung diseases. Bacterial products and inflammatory mediators have been implicated in inducing an influx of eosinophils into the respiratory tract subsequent to an acute inflammatory response. Therefore, to better understand the role of eosinophils in lung inflammation, we compared the ability of three known chemoattractants, formylmethionylleucylphenylalanine (FMLP), leukotriene B4 (LTB4), and platelet-activating factor (PAF), to induce human eosinophils to migrate across 3.0-microns-pore naked filters and human umbilical vein endothelial cells (HUVEC) and A549 human pulmonary type II-like epithelial (A549) cells cultured in monolayers on these filters. Kinetic experiments indicated that eosinophil migration through all three barriers occurred by 60 min and plateaued by 2 h. Each of these chemoattractants induced eosinophil migration in dose-responsive fashion across all three barriers. Although similar maximal eosinophil migration was observed, the doses at which this occurred varied, indicating that the rank order of potency through naked filters is FMLP > PAF > or = LTB4. However, their relative chemotactic potency through cellular barriers was different, with FMLP > LTB4 > PAF. In contrast to previous studies with neutrophils, the rank order of potency of the three chemoattractants was not influenced by the barrier through which the eosinophil migrated. Thus, these and previous data show that FMLP, LTB4, and PAF are eosinophil and neutrophil chemoattractants. Therefore, it is likely that these three agents are important mediators of granulocytic inflammatory responses in the lung, albeit with different potency profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Platelet-activating factor-induced human eosinophil transendothelial migration: evidence for a dynamic role of the endothelium.

Stimulated migration of eosinophils out of the bloodstream and into the lung is key in the development of tissue eosinophilia and inflammation in asthma. Platelet-activating factor (PAF) has been implicated as an important inflammatory mediator in asthma pathogenesis in part because of its chemotactic capacity. We therefore studied the ability of PAF to induce human peripheral blood eosinophil migration through naked filters and human umbilical vein endothelial cells (HUVECs) cultured on these filters. PAF induced eosinophil migration through both barriers in a time-dependent fashion, with maximal eosinophil migration occurring at 180 min. Significant eosinophil migration was observed at PAF concentration > or = 0.1 microM and was dose dependent up to 10.0 microM. No significant differences in eosinophil chemotactic responses were noted between naked filter and HUVEC barriers. The PAF receptor antagonist, WEB 2086, inhibited (> 85%) eosinophil transendothelial migration when co-incubated with PAF or when used as a pretreatment of either the eosinophils or HUVECs. However, WEB 2086 pretreatment of HUVECs did not inhibit PAF-induced neutrophil transendothelial migration, nor did it affect leukotriene B4-induced neutrophil or eosinophil transendothelial migration. Thus, the data indicate that the endothelial cell plays an important role in PAF-induced eosinophil inflammatory processes. Moreover, these data suggest that PAF's pathogenic role in asthma may in part be due to its ability to stimulate eosinophil migration across endothelial barriers and into the airways.

Azepines↗

PubMed1992

Comparison of methodologies to measure human lung histamine.

The measurement of histamine in samples obtained from human lung is important in determining the roles of histamine and mast cells in normal and disease states. We, therefore, compared different assays for the measurement of histamine in human lung samples. Both a single isotope enzymatic assay and a radioimmunoassay (RIA) were capable of accurately measuring the low concentrations of histamine (0.05-2.0 ng/ml) normally found in bronchoalveolar lavage fluid. The RIA was also able to measure histamine levels up to 1500 ng/ml in human lung tissue samples. Moreover, the RIA measurement of high levels of histamine in lung samples compared favorably to an automated spectrofluorometric method. Unlike either the single isotope enzymatic assay or the automated spectrofluorometric assay which have effective capabilities at less than and greater than 2 ng/ml, respectively, the RIA can accurately measure histamine levels from 0.05 to 1500 ng/ml. Since the RIA is easier to perform, less costly, and has a wider range of effectiveness, this assay should prove valuable in assessing histamine levels from a variety of human lung samples, thereby, providing an avenue to elucidate the roles of histamine and mast cells in lung functions.

Bronchoalveolar Lavage Fluid↗

PubMed1990

The incidence of a new human cross-reactive idiotype linked to subgroup VHIII heavy chains.

Cross-reactive idiotypes (CRI) on human rheumatoid factors (RF), which are identified by murine monoclonal antibodies (mAb), have proved useful in defining both the incidence and the structural characteristics of these autoantibodies. In this study, a new murine anti-idiotypic reagent, mAb B6, has been used to identify and define the expression of a distinct heavy chain CRI. The B6 CRI was found on 20% of monoclonal IgM (16 of 81), but on only 5% of monoclonal IgA (1 of 20) and on no monoclonal IgG. In addition, this CRI was expressed exclusively on a subset of Ig derived from the VHIII protein variable region subgroup. In immunoblotting experiments, the mAb B6 bound directly to the heavy (H) chains of CRI positive proteins. The B6 CRI was found frequently on monoclonal IgM-RF molecules, and the mAb B6 could inhibit the binding of the RF to its IgG antigen. It was also demonstrated that Staphylococcus aureus protein A (SpA), which has recently been shown to bind to the F(ab) region of VHIII molecules, could block the interaction of some B6 CRI positive IgM to the anti-CRI. These experiments suggest that the B6 CRI is a marker for one or a few VHIII genes and that it is expressed commonly on IgM paraproteins, many of which have RF activity.

Antibodies, Monoclonal↗

PubMed1989

A highly informative probe for two polymorphic Vh gene regions that contain one or more autoantibody-associated Vh genes.

Efforts to determine the role of specific Ig variable region (V) genes in human autoimmune responses have been hampered by the lack of suitably polymorphic probes. Recently we isolated a heavy chain V (Vh) gene, designated Humhv3005, that is 99% homologous to the 1.9III Vh gene and can encode an anti-DNA antibody. To study the relation between these two genes, different DNA fragments from the isolated Humhv3005 clone were used to probe Southern blots of human genomic DNA. A 1.6-kb Eco RI fragment (designated hv3005/E1.6) was found to hybridize with only one band in Eco RI-digested DNA, and with two major bands in Bam HI-digested DNA. Importantly, the sizes of the latter two bands were indistinguishable from the corresponding Bam HI fragment sizes of the isolated hv3005 clone and the isolated 1.9III clone, respectively. Population and family studies with the hv3005/E1.6 probe revealed five different hybridization patterns of these two characteristic bands, which defined nine possible genotypes for two human Ig Vh gene loci. Together the data demonstrate that hv3005/E1.6 is a highly informative probe for an autoantibody-associated Vh gene(s), and should prove useful in elucidating the role of Ig Vh genes in autoimmune diseases.

Autoantibodies↗