Comparison of rocket and crossed immunoelectrophoresis assays for determination of the level of actin complexing of Gc globulin

Objective. Gc globulin (vitamin D-binding protein) is a component of the extracellular actin scavenger system. The level of Gc globulin is reduced in patients with fulminant hepatic failure, septic shock and trauma. Furthermore, low levels of Gc globulin in patients with fulminant hepatic failure and multiple trauma have been found to correlate with the morbidity and mortality of patients. Owing to a large increase in the turnover of Gc globulin upon complex formation with actin, it may be important to determine both the total Gc globulin concentration and the degree of complexing with actin for estimating the clinical prognosis of a patient. For this reason, we have compared a crossed immuno-electrophoresis method (CIE), suitable for visualizing the degree of complexing with actin, with a rocket immuno-electrophoresis method (RIE), previously used for determination of the complex degree. Material and methods. Sera from healthy donors and from patients with acetaminophen-induced liver disease or trauma were investigated using CIE, RIE and enzyme-linked immunosorbent assay (ELISA). Results. Using the CIE, no Gc globulin-actin complexes were detected among healthy donors. Complexes were present in 21 of 39 patients with liver disease and 3 of 37 trauma patients. High complex ratios (> 20%) were found in 6 of 7 patients with hepatic encephalopathy. Using the RIE, complexes were detected in most samples. Conclusion. The results show that the CIE method may be used for determining the degree of actin complexing in conjunction with ELISA or RIE in determining the levels of total Gc globulin.