Quantitative and functional aspects of T-cell populations in human gut mucosa.

Lymphocytes were isolated from rectal biopsies and resected gut specimens through a simple mechanical technique, and assayed for T-cell quantitation and mitogenic response to PHA and PPD. T-cells were found in considerable numbers in gut mucosa of all groups, but in each case their percentage was lower than that of the autologous peripheral blood. The mitogenic response to PHA was found in general to be lower in the mucosal lymphocytes compared to those in blood, with the exception of the polyposis group which responded highly. No response of mucosal cells to PPD was seen. Inhibition studies done by means of mixed cultures revealed the presence of a suppressor activity in many mucosal lymphocytes, especially in the inflamed mucosa group, which may partly account for some low responses observed with mucosal lymphocytes. Further studies are under way to better define these quantitative and functional differences seen in gut mucosal cells, and to correlate differences with disease states.