Considerations for the Use of Blood Plasma and Serum for Proteomic Analysis

Abstract

Blood and serum are frequently used as samples for proteomic analysis. A consideration of the literature suggests that the differences between serum and plasma as samples are not appreciated by many investigators. There also appears to be a lack of understanding of the issues critical for the processing of plasma and serum samples for analysis. The major difference between plasma and serum is the removal of fibrinogen and associated proteins such as high-molecular weight von Willebrand factor and the variable addition of cellular secretion products as a result of the coagulation process. Factors influencing plasma quality include anticoagulant selection, processing, and storage. Factors influencing serum quality include collection container and clot retraction time. Various approaches for the removal of high abundance proteins such as albumin and immunoglobulin G will be discussed. While it is clear that the removal of these high abundance proteins provides for the analysis of otherwise obscured low-abundance proteins, studies have not been performed to document that some low-abundance proteins are also not removed by these techniques Furthermore, most studies do not have enough normal subjects to provide a statistically sound control value. Plasma and serum can be valuable samples for proteomic analysis but the preparation of the samples must be suitable for regulatory validation. Recommendations are presented for consideration.