The relation of serum anti-(GalNAc beta) and -para-Forssman disaccharide IgG levels to the progression and histological grading of gastrointestinal cancer.

Unlabelled: Earlier we found two unusual IgG-antibody specificities to GalNAc beta and GalNAc beta1-3GalNAc beta (para-Forssman disaccharide, PFdi) carbohydrate ligands in human serum. The aim of the study was to evaluate whether elevated antibody levels are related to the progression of gastrointestinal cancer and the histopathological grading.

Methods: Specific IgG levels were tested in 159 patients with gastric cancer, 88 patients with colorectal cancer and 96 blood donors by the ELISA using synthetic polyacrylaamide (PAA) conjugates, GalNAc beta-PAA and PFdi-PAA. Biochemical and haematological analyses were performed using automatic equipment.

Results: The anti-PFdi IgG levels were significantly higher in patients with gastric and colorectal cancer than in donors: in stages II-IV, P = 0.0002 - 0.04 (U-test). The elevated anti-PFdi IgG level was associated with the advanced gastric cancer: in stages II, III, IV vs stage I (P = 0.004 - 0.06) and in case of the tumor size T2 + T3 vs T1 (stages I, II; P = 0.03). Differences in anti-GalNAc beta IgG level were insignificant. No relation between antibody levels and the regional and distant metastases of gastric or colorectal cancer was found. The lower anti-GalNAc beta IgG level was associated with lower-differentiated carcinomas (P = 0.01 - 0.04). Prolonged postoperative changes in the levels of both antibodies during the follow-up were established. An elevation of both antibody levels in patients with gastrointestinal cancer was revealed after a surgical removal of G3-tumors (P = 0.003 - 0.01). The anti-PFdi IgG levels correlated with the levels of the C-reactive protein: r = 0.50, P = 0.003. The anti-GalNAc beta IgG levels correlated with the percentage of peripheral blood monocytes: r = 0.42, P = 0.002.

Conclusion: The association of the anti-PFdi IgG level with cancer progression suggests the implication of antibodies in the pathogenesis of gastrointestinal cancer. Further studies are required to identify natural targets of antibodies, their relation to other diseases, prognostic significance in cancer.