Specificity of polyclonal anti-p53 IgG for isolation of the soluble p53 antigen from human serum

The possibility to use anti-p53 IgG for isolation of the soluble p53 antigen as a serological tumor marker has been shown in our previous studies. In order to prove the specificity of such IgG, we compared the effectiveness of columns with anti-p53 IgG and IgG isolated from non-treated rabbits (regular IgG). The gel fiberglass (GFG) columns for affinity chromatography were prepared separately with both types of IgG. The same serum was percolated simultaneously through both columns and the results of elution were compared. The total concentration of tumor-associated antigens (TAA) eluted from the serum of cancer patients was similar in both TAA mixtures isolated either with anti-p53 IgG or with the regular IgG. Differences are manifest in the content of total proteins and amount of each eluted protein: a mixture eluted with the regular IgG contains several proteins whereas the anti-p53 IgG isolated only two proteins, p64 and p53. The amount of the soluble p53 antigen isolated from the cancer serum was significantly higher when it was isolated with anti-p53 IgG. The method developed in our laboratory was shown to be highly specific both to isolate proteins related to cancer (p53) and non-cancer disorders (p64). Data presented in this report show that such specificity can be achieved only if the anti-p53 IgG is used: the regular IgG obtained from non-treated animals isolate many proteins among which the concentration of specific p53 protein is lost.