Biomedical subjects

C O'Leary

Publications and source records attributed to C O'Leary.

24 records · Page 2Linked to original sources

PubMed1985

Preparation of interstitial lung cells by enzymatic digestion of tissue slices: preliminary characterization by morphology and performance in functional assays.

A technique is reported here for the quantitative extraction of live cells from the lung interstitium; it involves the incubation of slices of perfused lung in a mixture containing optimal concentrations of collagenase, DNAse, and fetal calf serum, followed by the simultaneous recovery and fractionation of cells released from the tissue matrix on a six-step discontinuous percoll gradient. Yields in the order of 10(8) viable cells per gram of lung were routinely achieved with tissues from rat, mouse and guinea-pig. Preliminary characterization of these cells has been performed in the rat by histological techniques (Giemsa staining, transmission electron microscopy), cytochemistry (acid phosphatase, esterase, peroxidase), by the capacity to bind monoclonal antibodies directed at lymphocyte surface markers, and by a range of functional tests. The cells comprised, on average, 32% macrophages, 44% lymphocytes (T and B cells and large granular lymphocytes), with small numbers of eosinophils, mast cells and epithelial cells. Transmission electron microscopy revealed minimal ultrastructural damage to extracted cells, with such functions as phagocytosis, FcR activity, mitogen responsiveness, antigen presentation, and NK-cell activity, being readily demonstrable. In addition, these activities segregated into defined areas of the six-step density gradient.

Animals↗

PubMed1985

T cell activation by antigen-presenting cells from lung tissue digests: suppression by endogenous macrophages.

Parechymal cells (PC) were prepared by digestion of perfused, lavaged rat lung in a mixture of collagenase and DNase, and harvested on a discontinuous percoll gradient. The process yielded on average 1.0 X 10(8) viable cells/gram tissue. PC were pulsed with soluble antigen, and tested for their capacity to trigger antigen-specific activation of immune T-cells in vitro, or to replace adherent accessory cells necessary for Concanavalin A (Con A)-induced T-cell proliferation. Unfractionated PC exhibited only minor antigen-presenting cell (APC) activity. However, removal of adherent or FcR-positive cells unmasked substantial APC activity. Subsequent experiments indicated that the majority of the APC banded at the top of the percoll gradient (density less than 1.048 g/ml). The same cell preparations substituted for adherent accessory cells in Con A- activation of T cells, suggesting capacity to secrete soluble factors such as interleukin-1 (IL-1) as well to present antigen. The PC preparation also contained T-cells, which were refractory to Con A stimulation unless endogenous adherent cells were first removed. Collectively, these data suggest the presence of non-adherent, FcR-negative, low density accessory cells in the lung parenchyma, capable of both APC activity and soluble factor production. Their T-cell-activation functions appear to be down regulated by endogenous adherent, FcR-positive cells. It is speculated that the accessory cells in these lung preparations may be dendritic cells, the activity of which is subject to inhibition by macrophages.

Animals↗

PubMed1984

ELISA plaque assay for the detection of antibody secreting cells: observations on the nature of the solid phase and on variations in plaque diameter.

This report examines the basis for variations in the size and number of ELISA plaques detected in vitro. The nature and concentration of antigen used to coat the solid phase is shown to be critical, high concentrations of polymerized antigen being optimal for low molecular weight proteins, while coating conditions for high molecular weight multideterminant antigens are similar to conventional liquid ELISA. Variations in plaque diameter are shown to reflect maturational changes in the immune response, and probably indicate differences in the affinity of antibody being secreted within a population of plasma cells.

Animals↗

PubMed1984

Long-lived IgE- and IgG-secreting cells in rodents manifesting persistent antibody responses.

BALB/c mice and BN rats manifesting persistent IgE and IgG responses were examined up to 1 year after immunization. A significant proportion of the ongoing antibody response in these animals survived lethal X-irradiation employing dosages sufficient to deplete B memory cells. The persistent IgE responses in both species were refractory to exogenous isotype-specific suppressor cells taken from tolerant syngeneic animals, which were shown to abrogate primary IgE responses in parallel tests. Employing a novel ELISA-based assay for plaque forming cells, long-lived radioresistant IgE- and IgG-secreting cells were identified in differing ratios in lymph nodes, spleen, and bone marrow of both species. These long-lived cells were shown to arise following maximum antigenic challenge with antigen plus adjuvant, and after repeated low-grade stimulation by antigen alone, including passive inhalation of dilute antigen aerosols.

Animals↗

PubMedDate not supplied

The prevalence of coeliac disease among female subjects having bone densitometry.

BACKGROUND: Osteoporosis frequently complicates coeliac disease but most studies focus on symptomatic patients at the time of diagnosis. Screening tests have revealed that many individuals with coeliac disease have mild, atypical, or absent symptoms. AIM: To evaluate the relationship between coeliac disease and osteopenia or osteoporosis in female subjects attending for bone densitometry. METHODS: We studied 371 female subjects attending for bone densitometry, without secondary causes of osteoporosis and included those with normal and with reduced bone mineral density. Mineral density was measured by dual energy X-ray absorptiometry. Screening for coeliac disease was by measurement of anti-endomysial antibody by indirect immunofluorescence. RESULTS: Two of 115 (1.7%) female subjects with normal bone density and five of 256 (1.9%) female subjects with sub-normal bone density were positive for endomysial antibody. Five subjects who underwent small bowel biopsy had histological changes suggestive of coeliac disease. CONCLUSIONS: In females referred for bone densitometry, endomysial antibody positivity was not more prevalent among those with reduced bone mineral density. Examining only patients with clinically detected coeliac disease may overestimate the frequency of complications. This study does not support population screening for coeliac disease in an area with a high frequency of the condition.

Absorptiometry, Photon↗

PubMedDate not supplied

Serum complexes of immunoglobulin A-alpha1 proteinase inhibitor in rheumatoid arthritis: association with current cigarette smoking and disease activity.

OBJECTIVE: To investigate whether high levels of serum immunoglobulin A-alpha1 proteinase inhibitor (IgA-alpha1PI) complexes are primarily associated with cigarette smoking or the rheumatoid arthritis (RA) disease process itself. METHODS: A case-control study consisting of 231 RA cases and 83 healthy hospital workers. A smoking history was taken for the study groups. The serum IgA-alpha1PI complex levels (arbitrary units, au) were determined using a sandwich ELISA. Erythrocyte sedimentation rate (ESR) and rheumatoidfactor (RF) measurements were recorded in each of the RA cases. The serum complex levels were compared between RA cases and controls matched for smoking history and between smokers and non-smokers in the RA cases and controls. RESULTS: Mean serum IgA-alpha1PI complex levels were significantly higher in RA current smokers than in non-smoking RA patients (17.4 v 11.9 a.u., p = 0.0001). Similarly, mean serum complex levels were significantly higher in control current smokers than control non-smokers (18.8 v 11.5 a.u., p = 0.003). Seropositive RA cases had significantly higher complex levels than seronegative cases. Patients with erosive disease had higher levels than non-erosive patients, although significance was lost after correction for current smoking and RF positivity. There was an association between ESR and serum IgA-alpha1PI complex levels which was independent of current smoking. Overall, there was no significant difference in complex levels between RA cases and controls after correction for current smoking. CONCLUSION: Raised serum IgA-alpha1PI complex levels are associated with current smoking in both RA and healthy controls. ESR levels in RA patients are also associated with serum complex levels independently of current smoking. Our data suggest that high IgA-alpha1PI complex levels can be generated either as a result of current smoking, or by an active disease process in RA patients.

Adult↗