Adenosine inhibits the release of arachidonic acid and its metabolites (AAM) in activated human peripheral mononuclear cells.

OBJECTIVE: The effects of adenosine (Ado) and subtype-specific activators of adenosine receptors (A(1), A(2A), A(2B) and A(3)) were studied on the release of arachidonic acid (AA) and its metabolites (AAM) from human peripheral mononuclear cells (monocytes). MATERIALS AND METHOD: Adenosine and the selective agonists and antagonists of adenosine receptors were used. (3)H-AA and its metabolites released into the medium were determined by measurement of the total (3)H radioactivity released without separating the AAM. RESULTS: In the cells activated by protein kinase C specific phorbol ester (phorbol 12-myristate 13-acetate) and Ca(2+) ionophore (A23187), adenosine and two subtype-specific receptor agonists, CPA(A(1)) and CGS 21680 (A(2A)) induced concentration-dependent inhibition of the release of AAM, whereas stimulation of A(2B) or A(3) receptors was ineffective. The rank order of potency for the inhibition of AAM release was as follows: CGS 21680 = CPA > adenosine > NECA (in the presence of ZM 24185 and DPCPX as A(2A) and A(1) adenosine receptor antagonists, respectively) = IB-MECA. Adenosine inhibited the release of AAM only at and above the concentration of 100 muM, whereas the inhibitory effect of A(1) and A(2A) receptor specific agonists appeared at a concentration of 10(-7) M. CONCLUSIONS: It can be concluded that adenosine physiologically may not have a significant effect on the AAM release of circulating monocytes, but in pathological conditions, where the local Ado concentrations increases, this nucleoside, through activation of A(2A) and A(1) receptors can exert, at least in part, an antiinflammatory action by decreasing proinflammatory AAM production.

Differences in the changes of allergen-specific IgE serum levels and the chemiluminescence of peripheral blood phagocytes in patients with allergic rhinoconjunctivitis during the ragweed season.

The objective of this study was to compare the changes in the values of allergen-specific serum IgE levels and zymosan-induced whole blood chemiluminescence (CL) in 41 patients who had exclusively only ragweed allergy in the season of acute symptoms of disease in July, August and September. All patients had allergic rhinitis or rhinoconjunctivitis. Each patient was investigated as a self-control. The ragweed-specific IgE levels were measured by enzyme immunoassay (EIA). The luminol amplified zymosan-induced CL of whole human blood was detected. The allergen-specific serum IgE levels showed slight, but not significant, gradually increasing elevations during the whole season. On the other hand, significant increases were found in the values of the basal but especially in the zymosan-stimulated CL of peripheral blood phagocytes during the acute phase of allergy. Both the basal and the zymosan-induced CL reflected significantly the activated state of the immune system. These observations clearly show that there are well detectable signs of the systemic activation of the immune system in allergic rhinoconjunctivitis beside the local alterations. In addition, the measurements of the basal and zymosan-induced CL of peripheral phagocytes could clearly reflect the clinical state of disease in vitro.