A new method for the isolation of p53 protein from the sera of cancer
and non-cancer patients has been developed. The method is based on the
utilization of a new modification of a support for affinity chromatog
raphy in the form of gel fiberglass (GFG) (R. Zusman, patent applicati
ons, Israel, 1992; USA 1993). The sera were percolated through GFG col
umns with entrapped rabbit IgG generated against the colon cancer anti
gens. Tumor-associated antigens were eluted from sera of cancer patien
ts in large amounts, up to 2.4 mg/ml serum/column. Concentrations of t
hese antigens in different sera and their affinity to anti-tumoral ant
ibodies were detected by ELISA. Western immunoblotting with commercial
monoclonal antibodies and SDS-PAGE identified the isolated antigens a
s the p53 protein. This protein has been isolated in the highest conce
ntration yet reported from the serum of cancer patients, up to 1 mg/ml
. The same protein has been found in the serum of healthy people and n
on-cancer patients but in significantly lower concentrations. Isolatio
n of p53 protein from sera of noncancer patients confirms the opinion
of some investigators that this protein should be considered not only
as an oncogene but also as a protein correlated with different changes
in the cell cycle.