Increased Avidity of the Sambucus nigra Lectin-Reactive Antibodies to the Thomsen-Friedenreich Antigen as a Potential Biomarker for Gastric Cancer

Abstract EN

Aim.

To determine whether the naturally occurring Thomsen-Friedenreich (TF) antigen-specific antibodies differ in avidity between cancer patients and controls to find a novel biomarker for stomach cancer.

Methods.

Serum samples were taken from patients with cancer and controls.

The level of TF-specific antibodies and their sialylation were determined using ELISA with synthetic TF-polyacrylamide conjugate as antigen and sialic acid-specific Sambucus nigra agglutinin (SNA).

The avidity was determined using ammonium thiocyanate as a chaotrope.

Results.

A significantly higher SNA lectin binding to anti-TF antibodies was found in cancer patients irrespective of disease stage.

The avidity of only IgM TF-specific antibodies was significantly higher in cancer patients compared to controls.

The SNA-positive anti-TF antibodies of cancer patients showed a significantly higher avidity, P<0.001.

The sensitivity and specificity of this increase for gastric cancer were 73.53% and 73.08%, respectively, with a 73.2% diagnostic accuracy.

The higher avidity of SNA-reactive anti-TF antibodies was associated with a benefit in survival of stage 3 cancer patients.

Conclusion.

The SNA-reactive TF-specific antibodies display a significantly higher avidity in gastric cancer patients compared to controls, which can be used as a potential serologic biomarker for gastric cancer.

It appears that IgM is the main target responsible for the above changes.