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Decreased immunoreactivity and binding activity of corticosteroid-binding globulin in serum in septic shock
M Pugeat1, A Bonneton, D Perrot
1Hospices Civils de Lyon, Hôpital de l'Antiquaille, France.
Insights
Septic shock significantly lowers corticosteroid-binding globulin (CBG) levels in patients. This study developed a radioimmunoassay (RIA) to confirm decreased CBG concentration, not altered binding activity, is responsible for reduced corticosteroid-binding globulin activity.
Area of Science:
- Biochemistry
- Endocrinology
- Immunology
Background:
- Corticosteroid-binding globulin (CBG) plays a crucial role in regulating cortisol bioavailability.
- Reduced CBG activity in serum is observed in patients with septic shock, but the underlying mechanism remains unclear.
Purpose of the Study:
- To investigate the mechanism responsible for the depletion of corticosteroid-binding globulin (CBG) activity in serum during septic shock.
- To quantify CBG concentration in septic shock patients using a newly developed radioimmunoassay (RIA).
Main Methods:
- Purification of human CBG using ammonium sulfate precipitation, affinity chromatography, and HPLC.
- Development of a radioimmunoassay (RIA) using a monospecific antiserum for human CBG.
- Measurement of CBG concentrations in patients with septic shock, nonseptic shock, and healthy controls.
Main Results:
- A radioimmunoassay (RIA) was successfully developed for quantifying human CBG.
- Patients with septic shock exhibited significantly lower CBG concentrations (22.9 mg/L) compared to controls (39.9 mg/L) and nonseptic shock patients (33.3 mg/L).
- A significant correlation (r = 0.619) was found between RIA-determined CBG concentrations and CBG binding capacity, with no significant difference in electrophoretic mobility.
Conclusions:
- The depletion of corticosteroid-binding globulin (CBG) activity in septic shock serum is primarily due to a decreased amount of CBG.
- The developed radioimmunoassay (RIA) is a reliable tool for measuring CBG concentrations in clinical settings.
- These findings highlight the impact of septic shock on the endocrine system and corticosteroid regulation.
Abstract:
To investigate the mechanism(s) responsible for the depletion of corticosteroid-binding globulin (CBG) activity in serum in septic shock, we developed a radioimmunoassay (RIA) for human CBG, using a monospecific antiserum to human CBG raised in rabbits. CBG was purified from pooled human serum by precipitation with ammonium sulfate and successive affinity chromatography treatments on corticosterone-Sepharose and concanavalin A-Sepharose. Final purification was achieved by HPLC on a diethylaminoethyl-PW (polymer matrix) ion-exchange column. Typical standard curves established for the CBG immunoassay showed parallelism for pure CBG and serial dilutions of sera from patients with septic or nonseptic shock and from healthy controls. Measurements of CBG by RIA showed a significantly (P less than 0.001) lower CBG concentration in patients with septic shock (22.9 +/- 5.9 mg/L, mean +/- SD; n = 23) than in controls (39.9 +/- 6.5 mg/L, n = 21) or in patients with nonseptic shock (33.3 +/- 6.5 mg/L, n = 12). The correlation between the concentrations determined by RIA and the CBG binding capacity was significant (r = 0.619, P less than 0.001, n = 33). The electrophoretic mobility of CBG was similar in sera from septic shock patients and normal subjects (Rf = 0.52-0.56). This suggests that the depletion of the corticosteroid-binding activity in serum during septic shock is associated with a decreased amount of CBG.