Induction of Unresponsiveness of Antigen-Specific T Lymphocytes by Oral Administration of Cedar Pollen Extract in Mice

Abstract

T lymphocyte unresponsiveness, induced in mice by a single gastric intubation of 0.2 ml cedar pollen extract (CPE, containing 4μg protein/ml)/mouse daily for 3 to 28 consecutive days, was evaluated by the absence of a proliferative response of popliteal lymph node (PLN) T lymphocytes to CPE in vitro. T lymphocyte unresponsiveness increased with the period of gastric intubation of CPE and reached more than 80% of the control on day 28. The unresponsiveness to CPE was antigen-specific and T lymphocyte-mediated. In vitro CPE-specific T lymphocyte proliferation was significantly suppressed by intestinal intraepithelial lymphocytes (IELs) and hepatic mononuclear cells (MNCs), but not by spleen cells or PLN T lymphocytes from mice fed CPE for 28 days. The effector activity of IELs and MNCs was obviously antigen-specific. These results suggest that lymphocytes in the intestine and liver of mice fed CPE would be involved in the induction and maintenance of CPE-specific T lymphocyte unresponsiveness.