Effects of oral administration of streptococcal preparation OK-432 on thoracic duct lymphocytes

One KE of streptococcal preparation OK-432 (PIC) was given orally to 6-week old male Wistar-Imamichi rats twice weekly, and control animals received comparable volumes of saline alone. Samples of thoracic duct lymph and posterior vena caval blood were collected prior to and 4 and 8 weeks following PIC. The T cell count of thoracic duct lymphocytes was about three times greater than that of venous blood specimens, and increased significantly in animals following PIC. Controls showed only a slight increase followed by a decrease, so that by 8 weeks of treatment with PIC, the thoracic duct T cell count revealed a significantly greater number in the PIC group than in the controls. In addition, after 8 weeks the per cent T cell subpopulation in thoracic duct lymph increased significantly in the treated group, but it declined in the control group. Concerning T cell subsets in thoracic duct lymphocytes, the percentage of suppressor/cytotoxic T cells showed a significant elevation in the control group after 4 weeks compared with the treated group. No other blood or lymph variables reached statistical significance in this respect.