Functional characteristics of lymphocytes isolated from the rat large intestine. Response to T-cell mitogens and natural killer cell activity.

Using successive ethylenediaminetetraacetic acid and collagenase treatments, two fractions of mucosal lymphocytes have been isolated from the rat large intestine that differ in morphologic and functional characteristics. Intraepithelial lymphocytes consisted largely of granular lymphocytes (91 +/- 6%) that did not respond to stimulation with phytohemagglutinin or concanavalin A, but had natural killer cytotoxic activity against the YAC-1 cell line. The natural killer cytotoxicity of the intraepithelial lymphocytes was specifically reduced by the addition of increasing numbers of unlabeled homologous tumor cells but not by unlabeled thymocytes. The sensitivity of different target cell lines to lysis by intraepithelial lymphocytes was the same as splenocytes from the same rat strain. Lymphocytes from the lamina propria contained 21 +/- 4% granular cells with the remainder being typical small lymphocytes. The lamina propria fraction responded well to stimulation with concanavalin A, phytohemagglutinin, and pokeweek mitogen, and also had natural killer activity against YAC-1 cells.