The Thomsen-Friedenreich Antigen and alpha Gal-specific Human IgG Glycoforms: Concanavalin A Reactivity and Relation to Survival of Cancer Patients

Glycan structures of IgG strongly influence the affinity for Fc gamma receptors and antibody effector functions. However, no particular attention has been paid yet to the glycosylation of tumor antigen-specific IgG. The objectives of this study were (i) to investigate the concanavalin A lectin (ConA) reactivity of human anti-Thomsen-Friedenreich (TF) and anti-alpha Gal specific IgG in gastric cancer patients and healthy controls and (ii) to evaluate whether the ConA-reactivity of anti-TF and anti-alpha Gal specific IgG is associated with the survival rate of patients with cancer. Total IgG was purified from the sera of patients with gastric cancer and healthy blood donors. The anti-TF and anti-alpha Gal glycotope specific IgG were detected with ELISA using synthetic saccharide-polyacrylamide conjugates as antigen. In parallel plate, the ConA reactivity of the anti-TF or anti-alpha Gal IgG was determined and the ConA index was calculated. Results show that serum anti-TF specific IgG antibodies of patients with cancer contain significantly higher content of ConA positive IgG glycoform compared to IgG of controls. No correlation between the ConA reactivity of anti-TF IgG and anti-alpha Gal IgG was observed. High level of anti-TF IgG ConA reactivity was associated with a significantly lower survival rate of patients with gastric cancer.