Gastric output of IgA in man: relation to migrating motility complexes and sham feeding

The immunologic reactivity of the gastric mucosa is poorly understood. The origin and dynamics of immunoglobulin A (IgA) occurring in the gastric lumen were investigated in healthy, Helicobacter pylori-negative volunteers.

Gastroduodenal manometric motility recordings were combined with gastric luminal perfusion, enabling calculation of gastric acid output and analysis of the total IgA output.

Acid output and total IgA correlated with the migrating motility complexes (MMC). The gastric IgA release showed maximal values in association with gastric motility phase III (maximal motor activity) and lowest values during phases I and II (none or irregular motor activity). The IgA output correlated with neither swallowed saliva (as indicated by amylase in the gastric perfusate) nor duodenogastric reflux (as indicated by gastric occurrence of bilirubin and/or duodenally infused PEG4000). Stimulation of gastric acid secretion by sham feeding during phase II-like motor activity (n = 6) induced a rapid and transient doubling of IgA output. There was no significant correlation between gastric acid secretion and gastric IgA release.

Substantial amounts of IgA are released into the human stomach, most likely originating from the gastric mucosa. The up-regulation of IgA release in association with the activity front of the MMC and anticipatory to food intake suggests a neuroendocrine control of gastric mucosal immune responses.