Intestinal exfoliated cells in infant diarrhoea: changes in cell renewal and disaccharidase activities.

Lactase deficiency, manifested clinically by lactose malabsorption, is often the only biochemical evidence of a residual disturbance of jejunal mucosal function after Escherichia coli enteropathy in the infant. Villous morphology is usually normal. A sustained depression of the processes of biochemical differentiation of lactase biosynthesis has been postulated to explain similar states of lactase deficiency, but a possible influence of altered epithelial cell turnover on the mucosal lactase levels has not been investigated. In ten infants with a residual lactose malabsorption, after E. coli infection, jejunal cell renewal activity and disaccharidase activities were studied by analysis of the exfoliated cells collected by lumenal perfusion. Significant increases in DNA and protein exfoliation and in the brush border activities of sucrase and lactase were observed during recovery from the malabsorptive disturbance. DNA and protein efflux increased almost linearly during a 20-day period. Lactase was initially four times more deficient than sucrase activity in the exfoliated cells. Both enzyme activities increased at almost identical rates. Therefore, it took longer for lactase activity to return to normal levels. The lactase/sucrase ratios approached normal at the end of the 20-day period. The changes in the exfoliating levels of the two enzymes, when analysed in relation to the increases in cell renewal activity, suggested a relationship between sucrase and lactase levels and cell age.