Evidence for a free N-acetylneuraminic acid

Abstract

A preliminary short follow-up study of Hanganutziu and Deicher (HD) antibody titre and sialic acid levels in sera from 7 patients with hepatoma was carried out. Weekly HD antibody titres were abnormal in 6 patients with titres of 4 of the 6 falling to normal in some weeks. Sialic acids levels, however were abnormal (3.830-6.82mmol/ l) compared to those of 33 normal sera (1.08-2.73 mmol/1) throughout the 8 week screening period. There was a poor correlation between the antibody tires and the sialic acid levels (r<0.50) suggesting that at some stage of malignancy, the tumour was expressing N-glycolylneuraminic acid (Neu5Gc), the epitope of HD antigens as well as shedding into circulation, excess N-acetylneuraminic acid (Neu5Gc). Neu5Gc is a tumor-associated antigen. Measurement of antibodies to this epitope have shown that the antibodies have a potential of offering an alternative method of determining tumor growth and/or metastases. A major follow-up study incorporating information on cancer type, disease stage, therapy and the immnunological status of the patient is called for.