Alteration of structural order of human erythrocyte ghost membrane by glucocorticoids and the influence of the glucocorticoid receptor antagonist RU 486.

High-dose pulse glucocorticoid therapy has been used successfully in the clinic in severe pathological conditions for about 20 years. The mode of glucocorticoid action after administration of such megadoses is inexplicable up to now. It is supposed that some effects may be due to membrane alterations. In the present in-vitro experiments the effect of dexamethasone, of further glucocorticoids, and of the glucocorticoid receptor antagonist RU 486, on structural order of human erythrocyte ghost membranes was investigated by determining the steady-state fluorescence anisotropy of diphenylhexatriene (DPH). Dexamethasone was found to induce a significant decrease in membrane structural order at concentrations of about 10(-6) M in a concentration-dependent manner. We found a correlation between the uptake of dexamethasone by the ghost membranes and the decrease in the structural order. The other glucocorticoids tested, methylprednisolone and corticosterone, were also effective at concentrations of 10(-5) M or greater. We observed no change in membrane structural order with RU 486 up to a concentration of 10(-4) M. However, simultaneous incubation of RU 486 with dexamethasone caused a distinct interference of RU 486 with dexamethasone. Thus, the glucocorticoid-induced membrane perturbation, the possibility to inhibit it by RU 486, and the inactivity of the structurally related progesterone, refer to relatively specific binding sites for the glucocorticoids in the membrane of erythrocyte ghosts.

The plasma corticosterone level in rat 6-sulfanilamidoindazole arthritis and influence of RU 486.

The inflammatory reaction of the hindpaws inducible in rats by systemic administration of the sulfonamide 6-sulfanilamidoindazole (6-SAI) is characterized by a special tolerance reaction, i.e. the paw inflammation decreases despite a continued medication of 6-SAI. We found no change of the plasma corticosterone level in 6-SAI-dosed animals, neither at the beginning of 6-SAI administration nor when the inflammation reached maximal values nor during the remission of paw swelling. Thus, a presumed regulatory increase of the endogenous glucocorticoid concentration cannot be the reason for the spontaneous remission of this special inflammatory process. Administration of the receptor antagonist RU 486 caused an increased corticosterone plasma level by about 40% but had no significant influence on paw swelling.

Precipitable immune complexes in Hodgkin's disease.

Sera from 28 untreated patients with Hodgkin's disease and from 120 healthy controls were investigated for the presence of circulating immune complexes using a modified 3% polyethylene glycol precipitation method with subsequent quantification of the precipitated protein. Elevated levels of precipitable protein were found in 79% (p less than 0.005) of Hodgkin's disease sera. The degree of elevation was associated with disease activity including the presence of B-symptoms. Constant and pronounced increase of precipitable protein was found in six patients with stage-III B nodular sclerosis subtype, thus exceeding the average amount of precipitable protein in healthy controls by a factor of 3-4. The erythrocyte sedimentation rate in 20 patients correlated with the amount of precipitable protein (r = 0.79). Additionally, partial component analysis of the precipitates was carried out by laser nephelometry. Immunoglobulins and complement components were identified as being major components of the precipitated material in sera both from patients and healthy controls, thus confirming the probability of the immune complex nature of the precipitates. Significant differences between patients and healthy controls concerned the amount of precipitable components. Elevation of precipitable IgM was found to be the most sensitive parameter (86% above means + 2 SD of normal controls, p less than 0.005). Increased amounts of precipitable IgG, C4, and Clq were found in 57-46% of patients' sera. Elevation of precipitable IgA and C3c were identified less often. The results suggest the quantification of precipitable immune complexes and their components to be of value as adjuncts in determining disease activity in Hodgkin's disease.