1. A DNA radioimmunoassay, sensitive in the range 25–1000 ng, has been developed to measure gastric mucosal cell loss. Validity of the assay was based on antibody specificity, absence of interference from gastric contents, parallel tracer displacement by dilutions of gastric and standard DNA, and crossover with colorimetric assay.
2. With this assay, gastric DNA shedding was examined in two animal species and man. In the guinea-pig stomach, DNA loss was 20–100 pg/h and in the canine Pavlov pouch, 260–580pg/h. In the canine Pavlov pouch stimulation of acid secretion by histamine and exposure to exogenous acid increased DNA output. In the normal human stomach DNA loss was 544 k 175 pg/h and in duodenal ulcer patients, 649 k 225 pg/li.
3. DNA radioimmunoassay provides a sensitive and reproducible measure of cell exfoliation from the stomach and may be a useful tool for studying aspects of gastric mucosal defence.