Isolation and functional characterization of chicken intestinal intra-epithelial lymphocytes showing natural killer cell activity against tumour target cells.

Intestinal intra-epithelial lymphocytes (IEL) of SC or FP chickens were isolated and examined for their natural killer (NK)-cell activity against chicken tumour cell lines, LSCC-RP9 (RP9), LSCC-RP12 (RP12), MDCC-MSB-1 (MSB-1) and MDCC-CU36 (CU36). In general, IEL of satisfactory yield and of good viability were obtained with EDTA treatment of the gut tissues, followed by rapid passages of the resultant cells through nylon-wool columns and centrifugation on two-step Percoll density gradients (45% and 80%). In 4-hr and 16-hr 51Cr-release assays, the NK-cell activity of chicken IEL depended not only upon the type of target cells but also upon the incubation time and the host genetic background. RP9, MSB-1 and CU36 were susceptible to NK lysis by IEL and by spleen cells, while RP12 was resistant to lysis even after a prolonged incubation. In kinetic studies the cytotoxicity was detactable from 2 hr after incubation and progressively increased up to 16 or 18 hr. The IEL of SC chickens revealed significantly higher levels of NK-cell activity against RP9 than FP-strain chickens, whereas their splenic NK-cell activity was not significantly different. Against MSB-1 targets, however, IEL of SC and FP chickens showed similar levels of NK-cell activity while their spleens did not (being higher in FP). When tested in FP chickens, IEL NK-cell activity was inhibited by the addition of unlabelled homologous target cells. In general, NK-cell activity was higher in the jejunum and ileum than in the duodenum and caecum. Efforts to enrich IEL NK-effector cells by discontinuous Percoll gradients were not successful. The results of the present study show that IEL of chicken intestine contain effector cells that can mediate NK-cell activity against chicken tumour cells.