RESUMO
The CH50 values in the serum and plasma, especially those from chronic hepatitis caused by hepatitis C virus (HCV), are strongly affected and reduced through a process known as cold activation. We attempted to optimize the conditions of blood sampling and storage for the CH50 assay with a recently developed liposome-based assay kit. The bloods were obtained from HCV hepatitis patients as well as healthy donors. Regardless of the temperature (room temperature, 4 degrees C or 37 degrees C) at which samples were kept until the assay, higher values were always obtained in the serum than in the plasma. The plasma samples could either be heparinized or given any of the other anticoagulants, EDTA-2K and sodium citrate, at the time of sampling. We also attempted to optimize the temperature at which the fresh specimens were left during the period from sampling to assay and the temperatures to freeze them for storage and to thaw for assays. In the assays immediately after sampling, higher values were obtained when the specimens were left at 37 degrees C than at room temperature or 4 degrees C. To store at -80 degrees C rather than at -20 degrees C and to thaw rapidly at 37 degrees C rather than slowly at room temperature were found to be advantageous.
