Isolation and purification of a squamous cell carcinoma of the head and neck-associated antigen identified by autologous antibody

Abstract

We have previously shown that detection of autologous antibody activity to squamous cell carcinoma of the head and neck may be augmented by dissociation of immune complexes. Western blot analysis with autologous antibody has identified a 60 kDa squamous cell carcinoma of the head and neck-associated antigen in spent media and immune complex-dissociated serum ultrafiltrate not recognized by normal human sera. Antigen-containing fractions of spent media were eluted from anion exchange columns immediately after serum albumin indicating that the antigen has an acidic pI < 4. Preparative purification of the squamous cell carcinoma antigen was accomplished by anion exchange of concentrated spent media (protein concentration 300 mg/ml) followed by lectin affinity chromatography with a Triticum vulgaris column. A single 60 kDa band was detected by silver stain and Western blot in antigen-containing fractions eluted following lectin affinity chromatography and SDS-PAGE. Final concentration of the antigen was determined to be 1 microgram/ml of protein with relative activity increased 1600 x over unfractionated spent media. We conclude that a squamous cell carcinoma of the head and neck-associated antigen, detected by autologous antibody, is an acidic 60 kDa glycoprotein.