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Biomedical subjects

C O'Mahony

Publications and source records attributed to C O'Mahony.

17 recordsLinked to original sources
PubMed1991

Gliadin antibodies identify gluten-sensitive oral ulceration in the absence of villous atrophy.

This study demonstrates gluten-sensitive recurrent oral ulceration (ROU) in the absence of gastrointestinal abnormalities which is associated with a humoral response to wheat protein. Ten patients with severe ROU were investigated; all had normal small intestinal biopsies. Four patients had raised levels of antibodies to alpha gliadin, a wheat protein fraction; in three of these four, the ulceration remitted on treatment with a gluten-free diet (G.F.D.) and relapsed on gluten challenge. None of the remaining six patients had raised alpha gliadin antibody (AGA) levels and none responded to G.F.D. Thus raised AGA levels can be used to identify patients with ROU who are likely to respond to a GFD.

Adult↗
PubMed1990

Raised PPD antibodies in active pulmonary tuberculosis.

Antibodies to purified protein derivative of tuberculin (PPD) were measured in 47 patients with active pulmonary tuberculosis and in various control subjects using an enzyme linked immunosorbent assay. Raised IgG anti PPD antibodies were found in 30 patients with active tuberculosis, in one of 28 patients with miscellaneous non tuberculous diseases and in one of 49 healthy control subjects. This gave the assay a sensitivity of 65% and a specificity of 98%. Antibodies were also measured in a further 20 patients with suspected tuberculosis but in whom microbiological evidence was absent. In eight of these patients active tuberculous disease was subsequently validated on the basis of clinical response to chemotherapy: raised PPD antibodies were found in six of this group but in none of the remaining 12 patients in whom the diagnosis of tuberculosis was considered doubtful. Further studies showed that patients' PPD antibody level fell over a one year period of successful therapy and that tuberculin skin testing and BCG vaccination did not cause a rise in antibodies in healthy subjects. These results suggest that the measurement of PPD antibodies is a useful adjunctive test in the diagnosis of tuberculosis.

Antibodies, Bacterial↗
PubMed1987

Immunoperoxidase demonstration of the cellular composition of the normal and coeliac small bowel.

Immunohistological analysis of the cellular composition of the small intestinal mucosa in a group of untreated and treated coeliac patients and non-coeliac control subjects was performed using monoclonal antibodies and an immunoperoxidase technique. A characteristic cellular distribution was observed within the normal mucosa. The intraepithelial and lamina propria compartments were occupied mainly by T suppressor/cytotoxic and T helper/inducer cells respectively. Further subdivision of lamina propria T helper/inducer cells with the Leu 8 antibody revealed that these were of the Leu 3a+ Leu 8- phenotype. Macrophages, defined by the RFD7 antibody, were seen to occupy the same microenvironment as T helper/inducer cells. T cells expressing the T cell activation antigen defined by anti-Ta1 were found with the normal lamina propria, although few cells were identified by the anti-Tac antibody. HLA-Dr antigens were expressed by stellate cells within the lamina propria, and also by the epithelial cells of the villi, but not by normal crypt epithelial cells. In untreated coeliac patients the distribution of the various cell types was essentially unchanged, although the number of these cells was markedly increased, including those which expressed the Ta1 antigen. A significant deviation from normal in the expression of HLA-DR antigens was found in the coeliac small bowel: these antigens were expressed not only on the villous epithelial cells but also on the epithelial cells of the crypts. Immunohistological findings in the treated coeliac patients were intermediate between the normal and untreated coeliac groups, and were completely normal in those patients with complete histological resolution of their disease. These results suggest that coeliac disease is accompanied by an enhanced stimulation of the normal mucosal immune response and do not imply a primary pathogenic role for the immune system in this disease.

Antigens, Surface↗
PubMed1985

Helper and suppressor T lymphocyte function in severe alcoholic liver disease.

The immune regulatory T cell status of patients with severe alcoholic liver disease (ALD) was investigated. Using monoclonal antibodies to identify lymphocyte subsets in 22 patients, a significant decrease in the percentage of T suppressor/cytotoxic cells (P less than 0.01) and increase in the percentage T helper/inducer population (P less than 0.05) was observed when the results were compared with 20 normal controls. However, when absolute numbers of these lymphocyte subsets were calculated the patient group did not differ significantly from the controls. Further studies revealed T immunoregulatory cell function to be normal. Concanavalin A induced suppressor cells resulted in equivalent inhibition of autologous cell mitogen responsiveness in the patient and control groups. In addition, purified patient T lymphocytes were demonstrated to provide normal help to and manifest normal suppression of IgG, IgA and IgM synthesis by allogeneic B cells. When spontaneous immunoglobulin synthesis by circulating mononuclear cells was investigated, a significant increase in IgA synthesis was found in the ALD patients (P less than 0.05). These results suggest that T cell immunoregulation is normal in patients with ALD and a defect in this system is not responsible for the increased synthesis of immunoglobulin observed in ALD.

Adult↗