Decreased levels of circulating lytic anti-T in the serum of patients with metastatic gastrointestinal cancer: a correlation with disease burden.

Using a cytotoxicity assay, we have shown that all of 40 normal human sera tested contained antibodies cytotoxic for neuraminidase-treated red blood cells in the presence of complement. The antibodies were shown to be specific for the T disaccharide by studies using a synthetic T antigen (formula: see text). Certain patients with metastatic gastrointestinal cancer were found to have depressed serum levels of anti-T when compared to normal controls. There was a correlation between depression of circulating anti-T and disease burden in that 83% of patients with extensive disease had lower than normal levels of cytotoxic anti-T as compared to 45% of patients with moderate disease and none with minimal disease. There was no correlation between the concentration of cytotoxic anti-T and the age of the patients, time since surgery or the type of therapy the patient was receiving. Patients with low levels of cytotoxic anti-T had normal levels of cytotoxic anti-sheep red blood cell antibody. Measurement of circulating anti-T in the serum of certain cancer patients may prove valuable in the monitoring of disease progression.