Relationship between mucosal levels of Helicobacter pylori-specific IgA, interleukin-8 and gastric inflammation

Mucosal IgA is important in local immune defence. Helicobacter pylori induces a specific IgA response in antral mucosa, but its immunopathology is unknown. Interleukin-8 (IL-8) has been suggested to be important in H. pylori-induced inflammation. Current information on the relationship between H. pylori-induced IgA and mucosal inflammation is limited. To investigate possible associations between mucosal-specific IgA, the toxinogenicity of H. pylori, mucosal levels of IL-8 and gastric inflammation, 52 endoscoped patients were studied. These comprised 28 patients with peptic ulcer and 24 with non-ulcer dyspepsia. Of these patients, 38 had H. pylori infection: 28 with peptic ulcer and 10 with non-ulcer dyspepsia. Antral biopsies were taken for histology, H. pylori culture and measurement of mucosal levels of IL-8 (pg/mg) and specific IgA (A₄₅₀×1000) by ELISA. Mucosal H. pylori IgA was detectable in 35 out of 38 patients with H. pylori infection, with a median (interquartile) level of 220 (147, 531) units. There was no significant difference in mucosal levels of the IgA antibodies between patients infected with cytotoxin-positive or cagA-positive strains of H. pylori and those with toxin-negative or cagA-negative strains. The IgA levels in those patients with severe neutrophil infiltration were lower than in those with mild or moderate infiltration (P< 0.05). There was a weak inverse correlation between antral mucosal IgA and IL-8 in infected patients (r = -0.36; P = 0.04). H. pylori infection induced a significant local mucosal IgA response in most infected patients. The level of IgA antibodies does not appear to be correlated with the toxinogenicity of H. pylori. However, patients with severe active inflammation appear to have decreased levels of IgA. An inverse correlation between mucosal IL-8 and IgA may suggest that IL-8-induced inflammation compromises the mucosal IgA defence and renders the mucosa susceptible to further damage.