Expression of alpha-gal epitopes on ovarian carcinoma membranes to be used as a novel autologous tumor vaccine.

Abstract

OBJECTIVE:

Poor presentation of tumor-associated antigens (TAA) to the immune system remains a major obstacle to effective anti-tumor vaccine therapy. The aim of this study is to demonstrate the feasibility of producing a novel autologous tumor vaccine from ovarian carcinoma that is expected to have increased immunogenicity. The strategy is based on the ability of the anti-Gal IgG antibody (a natural antibody comprising 1% of IgG in humans) to target tumor membranes expressing alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R) to antigen-presenting cells (APC).

STUDY DESIGN:

Freshly obtained ovarian carcinoma tumors are homogenized, washed, and incubated with a mixture of neuraminidase, recombinant alpha1,3 galactosyltransferase (ralpha1,3GT) and uridine diphosphate galactose (UDP-Gal) to synthesize alpha-gal epitopes on carbohydrate chains of glycoproteins of these membranes. Subsequently, the processed membranes are analyzed for expression of alpha-gal epitopes and for the binding of anti-Gal.

RESULTS:

Incubation of 3 g of ovarian carcinoma membranes, from five different patients, at 100 mg/ml, mixed together with ralpha1,3GT (50 microg/ml), neuraminidase (1 mU/ml), and UDP-Gal (2 mM), resulted in the effective synthesis of alpha-gal epitopes to the extent of approximately 2 x 10(11) epitopes/mg of tumor membranes. As a result of this de novo expression of alpha-gal epitopes, the tumor membranes readily bound purified anti-Gal antibody, as well as anti-Gal in autologous serum.

CONCLUSIONS:

The method described in this study is very effective in the synthesis of many alpha-gal epitopes on tumor membranes obtained from ovarian carcinoma. These novel epitopes readily bind the naturally occurring anti-Gal antibody. This technique of opsonization of alpha-gal-modified autologous tumor membranes carrying TAA is expected to increase effective uptake of the vaccine by APC, which is key to successful anti-tumor vaccination.

• Authors: Uri Galili, Zhao-chun Chen, Koen DeGeest
• Journal: Gynecologic oncology (Gynecol Oncol) Vol. 90 Issue 1 Pg. 100-8 (Jul 2003) ISSN: 0090-8258 [Print] United States
• PMID: 12821349 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cancer Vaccines
• Epitopes
• Immunoglobulin G
• Membrane Glycoproteins
• Trisaccharides
• alpha-galactosyl epitope
• Uridine Diphosphate Galactose
• Galactosyltransferases
• N-acetyllactosaminide alpha-1,3-galactosyltransferase
• Neuraminidase

Topics

• Antigen-Presenting Cells (immunology)
• Cancer Vaccines (immunology)
• Carbohydrate Sequence
• Cell Membrane (immunology, metabolism)
• Enzyme-Linked Immunosorbent Assay
• Epitopes (biosynthesis, immunology)
• Female
• Galactosyltransferases (metabolism, pharmacology)
• Humans
• Immunoglobulin G (blood, immunology)
• Membrane Glycoproteins (immunology)
• Molecular Sequence Data
• Neuraminidase (metabolism, pharmacology)
• Ovarian Neoplasms (immunology, metabolism)
• Trisaccharides (biosynthesis, immunology)
• Uridine Diphosphate Galactose (metabolism, pharmacology)