Biomedical subjects

K A Byron

Publications and source records attributed to K A Byron.

8 recordsLinked to original sources

PubMed1997

House dust mite immunotherapy results in a decrease in Der p 2-specific IFN-gamma and IL-4 expression by circulating T lymphocytes.

BACKGROUND: Allergen-specific immunotherapy (IT) can be an important adjunctive therapy in the treatment of allergic disorders. Although it has now been used for over 80 yr, the precise mechanism of action remains unclear. Recently a number of studies have shown that cytokine production may be modified by IT, but different protocols have been used and different results obtained. OBJECTIVES: The aims of the present study were: (1) to document the allergen-specific expression of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) by peripheral blood cells in both untreated house dust mite (HDM) allergic patients (non-IT) and following at least 10 months of HDM-specific IT (post-IT); and (2) to determine whether alterations in these critical regulatory cytokines correlated with the clinical outcome of IT. METHODS: IT was undertaken with nine fortnightly subcutaneous injections of increasing amounts of a Dermatophagoides pteronyssinus (Dpt) extract, reaching a final dose of 10,000 PNU. This was followed by 6- to 8-monthly maintenance injections of 5000 PNU. For cytokine measurement, mononuclear cells were separated from peripheral blood and stimulated with the major Dpt allergen, Der p 2, for 18 h, after which mRNA was isolated and IL-4 and IFN-gamma cDNA were amplified by polymerase chain reaction (PCR). The presence of the particular cytokine was determined by visualization following electrophoresis on an agarose gel. The study was observational in nature being open and without a placebo group. RESULTS: Fifteen Dpt-sensitive patients who had not received HDM IT (non-IT), and 16 who had, were studied. In the non-IT group, 80% expressed IL-4 and 75% expressed IFN-gamma. In those post-IT, only 12.5% expressed IL-4 and 19% IFN-gamma. The two patients still expressing IL-4 post-IT had had very little clinical response. Six patients were studied both pre- and post-IT. Prior to IT, three were positive for both cytokines, two positive for IL-4 alone and one for IFN-gamma. Post-IT, all six were negative for IL-4 and five were negative for IFN-gamma. CONCLUSION: Allergen-specific IT results in a reduction in expression of the critical cytokines IL-4 and IFN-gamma in circulating lymphocytes. It is possible that this is a contributary mechanism in the beneficial effect of IT.

Adolescent↗

PubMed1995

Serum IL-4, IL-10 and IL-6 levels in inflammatory arthritis.

As the available in vitro and in vivo data suggest that interleukin (IL)-4 and IL-10 have immunosuppressive activity, our hypothesis was that serum IL-4 and IL-10 levels would correlate inversely with parameters of inflammation in patients with inflammatory arthritis. IL-4 was detected in the serum of 12 out of 140 patients with rheumatoid arthritis (RA), which was increased compared to the proportion found with patients with osteoarthritis (OA; P < 0.02). In addition, IL-4 was detected in the serum of 2 of 19 patients with systemic lupus erythematosus (SLE), 2 of 24 patients with psoriatic arthritis and 1 of 5 patients with Behçet's syndrome. No IL-4 was detected in patients with the following conditions: OA (58 patients), gout (17 patients), ankylosing spondylitis (6 patients), Reiter's syndrome (6 patients), polymyalgia rheumatica (6 patients), temporal arteritis (5 patients) and scleroderma (3 patients). No IL-10 was detected in any of the sera tested. We discuss the possible relevance of these results to the regulation of the immune response evident in inflammatory arthritis.

Adolescent↗

PubMed1994

Dermatophagoides pteronyssinus II-induced interleukin-4 and interferon-gamma expression by freshly isolated lymphocytes of atopic individuals.

Cytokines are known to play a major role in mediating many of the immunological and pathological features of allergic disease. Much of our understanding of cytokine production in response to allergens has come from studying allergen-specific T cell clones following long-term in vitro culture. This has largely been due to the lack of sufficiently sensitive assays to measure allergen-induced cytokine production by freshly isolated peripheral blood mononuclear cells (PBMCs). Here we have used the polymerase chain reaction to amplify reverse transcribed interleukin-4 (IL-4) and IFN gamma mRNA expressed by allergen-stimulated PBMCs from a variety atopic individuals. Using Der p II, a major allergen of the house dust mite (HDM) Dermatophagoides pteronyssinus, we have demonstrated that cells from HDM-sensitive atopic patients (n = 12), can be induced to express either IL-4 alone (three patients), IL-4 and IFN gamma (six patients), IFN gamma alone (two patients) or neither cytokine (one patient). Cells from 13 non-atopic control individuals were also stimulated with Der p II and cytokine mRNA production was studied. None expressed IL-4, while seven of 13 transcribed IFN gamma. Our results suggest that atopic individuals have allergen-reactive T cells at various stages of differentiation, with respect to the cytokines they produce. The use of this technique will aid in the further understanding of specific cellular hypersensitivity in allergic disease.

Animals↗

PubMed1994

IL-4 production is increased in cigarette smokers.

Cigarette smoking has been associated with both increases in serum levels of total IgE and an increased risk of developing allergic-like symptoms. IL-4 and interferon-gamma (IFN-gamma) have reciprocal roles in the regulation of IgE synthesis, and as such prompted us to evaluate, in smokers, the production of these two cytokines. We demonstrate that phytohaemagglutinin (PHA)-induced IL-4 production by peripheral blood mononuclear cells (PBMC) of smokers (n = 19) is significantly higher than that of non-smokers (n = 10, P < 0.005). In addition, PBMC from heavy smokers, defined by the number of cigarettes smoked per day, produced significantly higher levels of IL-4 than those of light smokers. No difference between the groups was found for IFN-gamma production. Our data suggest an imbalance in cytokine production occurring in individuals who smoke. This imbalance, favouring IL-4 production, may be part of the mechanism responsible for the observed increases in serum IgE and allergic-like symptoms associated with cigarette smoking.

Adult↗

PubMed1992

Interferon-gamma production in atopic dermatitis: a role for prostaglandins?

Peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis (AD) have a reduced capacity to produce interferon-gamma (IFN-gamma) in vitro, in response to phytohaemagglutinin (PHA) when compared to healthy non-atopic controls. This defect appears to correlate closely with the severity of AD at the time of sampling, with less IFN-gamma being produced by cells from patients with more severe disease. Enhanced production of IFN-gamma was observed as the patients clinical symptoms improved. In addition, IFN-gamma production could be increased by either pre-culturing the cells for 3 days prior to PHA stimulation or by addition of indomethacin to the culture medium. These observations suggest that the mechanism of reduced IFN-gamma production in AD is unlikely to be due to an intrinsic cellular defect. The possibility that prostaglandins mediate the suppressed production of IFN-gamma in AD was supported by demonstrating that exogenous prostaglandin E2 (PGE2) inhibited IFN-gamma production in PHA-stimulated PBMC. PGE2 at a physiological concentration (10(-9) M) was also shown to enhance interleukin 4 induction of IgE synthesis by PBMC cultures. Our data suggest that alterations in prostaglandin metabolism play a crucial role in the pathogenesis of AD by inhibiting the production of IFN-gamma.

Cells, Cultured↗

PubMed1992

Hydrocortisone inhibition of human interleukin-4.

Glucocorticoids are known to inhibit mitogen-induced proliferation of T cells by suppressing the production of interleukin-2 (IL-2). These hormones have also been shown to inhibit the production of other cytokines, namely IL-1 and interferon-gamma (IFN-gamma). It is demonstrated here that hydrocortisone is able to inhibit mitogen-induced production of human IL-4, both at the secreted protein, as well as at the mRNA level. This effect may explain, in part, the immunosuppressive effects of glucocorticoids in the treatment of allergic disease.

Cells, Cultured↗

PubMed1991

Recombinant interferon-gamma inhibits the expression of IL-4 receptors on human lymphocytes.

Interferon gamma (IFN-gamma) has been shown to inhibit many of the activities of IL-4, including the induction of IgE synthesis and the proliferation of T cell clones. Here we demonstrate that IFN-gamma is able to inhibit the expression of IL-4 receptors on peripheral blood lymphocytes from both normal healthy donors and from patients with chronic lymphocytic leukaemia. Inhibition was shown to be dose-dependent and did not affect the binding affinity of the receptor as shown by Scatchard analysis. IFN-gamma was unable to displace labelled IL-4 from its membrane receptor, which demonstrates that IFN-gamma and IL-4 do not compete for the same membrane binding protein. The ability of IFN-gamma to down-regulate IL-4 receptors may be important in controlling certain immune responses.

Cells, Cultured↗

PubMed1989

Alpha 1-antitrypsin phenotypes in homosexual men.

The alpha 1-antitrypsin (AAT) phenotype was determined by isoelectric focusing in 215 male homosexuals and compared with those in 208 male heterosexuals. The incidence of abnormal phenotypes was 16.3% in the homosexual group which was significantly different (p less than 0.03) than the 8.7% in the heterosexual group. There was no difference in the phenotype distribution between homosexuals who were anti-human immunodeficiency virus reactive and those who were non-reactive. It suggests that investigation into the interplay of factors associated with homosexuality could include genetic as well as psychological and social factors.

HIV Seropositivity↗