TY - JOUR
T1 - Phosphodiesterase inhibition by Ro 20-1724 reduces hyper-IgE synthesis by atopic dermatitis cells in vitro
AU - Cooper, K. D.
AU - Kang, K.
AU - Chan, S. C.
AU - Hanifin, J. M.
N1 - Funding Information:
Manuscript received June 4, 1984; accepted for publication November 28, 1984. Supported in part by NIH Training Grant 2 T32 AM07 l53 and NIH Grant 1 TOl All.8615 and by a grant from the Medical Research Foundation of Oregon. Reprint requests to: Kevin D. Cooper, M.D., Dermatology Branch, Natio nal Institutes of Health, Bethesda, Maryland 20205. Abbreviations: AD: atopic dermatitis BSA: bovine serum albumin cAMP: cyclic AMP FCS: fetal calf serum M NL: mononuclear leukocyte(s) Mo: monocyte PBS: phosphate-buffered saline PDE: phosphodiesterase PGE1: prostaglandin Et Ro: Ro 20-1724 Patients with atopic dermatitis (AD), a disease characterized by high tissue histamine levels [1,2], demonstrate a variety of immunologic and pharmacologic abnormalities. We have shown that blood leukocytes from patients with AD show markedly reduced cAMP responses to isoproterenol, histamine, and prostaglandin E1 (PGE1) [3). Similarly reduced responses were observed in normal leukocytes desensitized by micromolar concentrations of histamine [3,4]. It. appears that this lack of cAMP responsiveness is due to rapid hydrolysis of cAMP by increased intracellular cAMP phosphodiesterase (PDE) as evidenced by our findings that cells from patients with AD, as well as normal cells exposed to low concentrations of histamine, have a dramatic and consistent elevation of a high-activity form of PDE [4,5]. Increased leukocyte cAMP PDE and consequent lack of cAMP-mediated immunoregulatory influences may provide a permissive effect on leukocyte functions such as lgE production [6] and histamine release [7). Patients with AD have elevated serum IgE levels [6] and this is reflected in the finding that AD leukocytes placed in culture spontaneously produce elevated levels of IgE over a 7-to 10-day culture period [8-11). While largely independent of radioresistant T-cell help [9,11], the IgE-producing B cells are sensitive to suppression by high numbers of added allogeneic normal T cells. Although purely allogeneic effects were not excluded in all these studies [8,12,13], others have excluded this mechanism [9]. Several of these studies revealed a lack of T suppressor activity by cells from AD or hyperimmunoglobulinemia E syndrome patients but these findings have not been consistent, and some patients, whose mononuclear leukocytes (MNL) overproduce IgE, clearly have normal T suppressor function [8,9,11,12]. A recent study showed that T-cell supernatants from patients with AD enhanced IgE synthesis by B cells [14). The complete role of T lymphocytes in elevated lgE production by cells from patients with hyperimmunoglobulinemia E states remains uncertain. The purpose of this study was to determine the effect upon in vitro lgE synthesis by leukocytes from patients with AD when the elevated PDE activity was lowered by the PDE inhibitor Ro 20-1724 (d,l-1,4-[3-butoxy-4-methoxybenzyl)-2-imidazolidinone). Using a modification of the "panning" method for sorting leukocytes with monoclonal antibodies [15-19], the leukocyte subsets affected by the drug were identified.
PY - 1985
Y1 - 1985
N2 - Peripheral blood mononuclear leukocytes (MNL) from patients with atopic dermatitis spontaneously produce large amounts of IgE in vitro. These cells also show markedly elevated levels of cAMP phosphodiesterase (PDE) which may be responsible for the observed abnormal cAMP responsiveness. Treatment of atopic dermatitis MNL with varying concentrations of the cAMP PDE inhibitor Ro 20-1724 resulted in progressively decreasing amounts of IgE synthesis, statistically significant at the 10-4 M and 10-5 M concentrations. There was a close correlation between PDE inhibition and inhibition of IgE synthesis, r = 0.93, p<0.05. To define the cellular target of the drug, we used monoclonal antibodies directed toward MNL subsets (Lyt 3, OKT8, OKT4, monocyte-myeloid) in a modified 'panning' method to perform experiments with purified subsets. With untreated subsets, removal of OKT4-positive cells significantly reduced IgE synthesis; readdition of OKT4-positive cells enhanced IgE synthesis. Pretreatment of T cell-depleted MNL with Ro 20-1724 resulted in significantly more inhibition of IgE synthesis than did pretreatment of T enriched cells prior to recombination with the reciprocal untreated subset and subsequent culture. Similarly, pretreatment of monocyte-depleted cells resulted in significantly more inhibition of IgE synthesis than pretreatment of monocyte-enriched cells prior to recombination and culture. The majority of the effect appeared to be mediated by a direct effect on the B cells. However, some inhibition of IgE synthesis was also achieved through pretreatment of T enriched cells. Since pretreatment of isolated suppressor/cytotoxic or helper/inducer T-cell subsets did not give the same degree of inhibition as with unfractionated T cells, a T-T interaction may be involved in this aspect. The imidazolidinone derivative, Ro 20-1724, significantly and consistently inhibited both the elevated cAMP phosphodiesterase activity and the elevated spontaneous IgE synthesis of MNL from patients with atopic dermatitis. These findings demonstrate a previously undescribed link between cAMP PDE levels and in vitro IgE synthesis.
AB - Peripheral blood mononuclear leukocytes (MNL) from patients with atopic dermatitis spontaneously produce large amounts of IgE in vitro. These cells also show markedly elevated levels of cAMP phosphodiesterase (PDE) which may be responsible for the observed abnormal cAMP responsiveness. Treatment of atopic dermatitis MNL with varying concentrations of the cAMP PDE inhibitor Ro 20-1724 resulted in progressively decreasing amounts of IgE synthesis, statistically significant at the 10-4 M and 10-5 M concentrations. There was a close correlation between PDE inhibition and inhibition of IgE synthesis, r = 0.93, p<0.05. To define the cellular target of the drug, we used monoclonal antibodies directed toward MNL subsets (Lyt 3, OKT8, OKT4, monocyte-myeloid) in a modified 'panning' method to perform experiments with purified subsets. With untreated subsets, removal of OKT4-positive cells significantly reduced IgE synthesis; readdition of OKT4-positive cells enhanced IgE synthesis. Pretreatment of T cell-depleted MNL with Ro 20-1724 resulted in significantly more inhibition of IgE synthesis than did pretreatment of T enriched cells prior to recombination with the reciprocal untreated subset and subsequent culture. Similarly, pretreatment of monocyte-depleted cells resulted in significantly more inhibition of IgE synthesis than pretreatment of monocyte-enriched cells prior to recombination and culture. The majority of the effect appeared to be mediated by a direct effect on the B cells. However, some inhibition of IgE synthesis was also achieved through pretreatment of T enriched cells. Since pretreatment of isolated suppressor/cytotoxic or helper/inducer T-cell subsets did not give the same degree of inhibition as with unfractionated T cells, a T-T interaction may be involved in this aspect. The imidazolidinone derivative, Ro 20-1724, significantly and consistently inhibited both the elevated cAMP phosphodiesterase activity and the elevated spontaneous IgE synthesis of MNL from patients with atopic dermatitis. These findings demonstrate a previously undescribed link between cAMP PDE levels and in vitro IgE synthesis.
UR - http://www.scopus.com/inward/record.url?scp=0021795462&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0021795462&partnerID=8YFLogxK
U2 - 10.1111/1523-1747.ep12272486
DO - 10.1111/1523-1747.ep12272486
M3 - Article
C2 - 3998494
AN - SCOPUS:0021795462
SN - 0022-202X
VL - 84
SP - 477
EP - 482
JO - Journal of Investigative Dermatology
JF - Journal of Investigative Dermatology
IS - 6
ER -