IN-VITRO EVALUATION OF THE ROLE OF ANTIBODIES AGAINST HELICOBACTER-PYLORI IN INHIBITING ADHERENCE OF THE ORGANISM TO GASTRIC CELLS

Background-Once Helicobacter pylori infection is established, it is di fficult to eradicate despite a persistent systemic and local immune re sponse. It is not known whether immunisation can be used to prevent H pylori infection in humans. Aims-To evaluate the effect of the human i mmune response on adherence of H pylori to gastric cells. Methods-Huma n milk from a woman infected with H pylori and milk from a non-infecte d woman were each fractionated by chromatography on DEAE cellulose. Ba cteria were incubated with either serum, human milk, human milk fracti ons, or secretory IgA before incubation with Kato III cells (cells fro m a gastric adenocarcinoma cell line). Bacterial adherence to the cell s was assessed using flow cytometry. Results-Serum from both the H pyl ori infected and non-infected women killed H pylori. This resulted fro m the action of complement as heating the serum to 56 degrees C for 30 minutes abolished the bactericidal activity. Immunoglobulin fractions from serum of both infected and non-infected women did not inhibit H pylori adherence to Kato III cells. Human milk from the woman infected with H pylori and from the non-infected woman inhibited binding of H pylori to Kato III cells by 50 to 70%. Secretory IgA isolated from hum an milk had minimal inhibitory effect on adherence and this was notabl y less than the inhibitory effect of whole human milk. Conclusions-Hum an milk inhibits adherence of H pylori to Kato III cells and this inhi bition is independent of whether or not the donor is infected with H p ylori. Secretory IgA has minimal inhibitory effect on H pylori adheren ce.