Human monoclonal antibodies from stomach carcinoma patients react withhelicobacter pylori and stimulate stomach cancer cells in vitro

Abstract

Background. In recent studies, an increased incidence of gastric adenocarcinomas was observed in patients with Helicobacter pylori infection. However, the extent to which this coincidence is caused by immunologic mechanisms is unknown. Methods. Two human monoclonal antibodies (MoAbs) from patients with stomach carcinoma and H. pylori‐associated gastritis were isolated and established by fusion of spleen cells with the heteromyeloma HAB‐1. The reactivity of these human MoAbs was investigated in functional adhesion assays and on Western blots of tissue, tumor cell, and bacterial extracts. Their stimulation and proliferation were tested by the MTT test and 3‐Hthymidine incorporation tests. Results. The two monoclonal immunoglobulin‐Mantibodies, 103/51 and 105/79, inhibited adhesion of tumor cells. On bacterial extracts antibody 103/51 identified protein bands of 55 kilodaltons (kd) and 80 kd, and in tumor cell extracts, a specific protein of approximately about 110 kd and 140 kd. Antibody 105/79 identified a 55 kd protein in bacterial extracts and a 110 kd protein intumor extracts. In addition, in the 3‐H‐thymidine incor‐poration and MTT assay the antibodies showed a stimulatory and growth‐enhancing effect on tumor cells in vitro. A similar activity was observed in sera from patients with gastric carcinoma, indicating a physiologic role of such antibodies in vivo. Conclusion. The human monoclonal antibodies described here react with H. pylori and cross‐react with and stimulate gastric carcinoma cells. It is possible that the production of these antibodies is primarily stimulated by bacterial antigens which cause chronic gastritis and that they might be indirectly responsible for the recently described higher incidence of gastric cancer because of the simultaneous reaction and stimulation of tumor cells they cause.

Lipoptosis

“…The fully human monoclonal IgM antibody PAM-1 was isolated from a patient with a stomach carcinoma, too (24). The PAM-1 receptor was found to be a M r 130,000 integral membrane glycoprotein (15), homologous to cysteine-rich fibroblast growth factor receptor 1 (25).…”

A Novel Proliferation-Associated Variant of CFR-1 Defined by a Human Monoclonal Antibody

“…As stated in our previous publications (Vollmers et al, 1994;Hensel et al, 1999b), the antibody 103/51 leads to the stimulation of cell line 23132 in vitro. We measured the stimulating ao antibody 103/51 with the mitochondrial hydroxylase assay (MTT), which is a standard assay for proliferation (Carmichael et al, 1987).…”

“…We have recently shown that stimulating antibodies like the one described here frequently occur in stomach cancer patients, and also that 4 of 11 tumorreactive monoclonal antibodies lead to cell stimulation (Hensel et al, 1999b;Vollmers et al, 1994). Common antigens of the stomach mucosa are the gastric Hϩ/ K(ϩ)-ATPase (Toh et al, 1990) and Lewis blood group antigens .…”

“…For the assays described, cells were detached with trypsin/ EDTA and washed twice with phosphate buffered saline (PBS) before use. The human hybridoma cell line 103/51 was produced and grown as described (Vollmers et al, 1994). Purification of the IgM antibodies was performed as described elsewhere (Vollmers et al, 1998).…”

“…In recent publications, we described that the human antibody 103/51, which was isolated from a stomach cancer patient with diffuse-type adenocarcinoma, crossreacts with H. pylori and stomach cancer cells (Vollmers et al, 1994). The antibody has a mitotic effect on stomach carcinoma cells in vitro by binding to a 130-kd membrane receptor (Hensel et al, 1999b).…”