Effect of the proteoglycan (PSK) on lymphocyte subsets in normal rats

The effect of the proteoglycan biologic response modifier, PSK, on lymphocyte subsets was investigated in normal rats. Six-week-old male SPF Wistar-Imamichi rats were fed a diet containing 2% PSK. Peripheral blood lymphocytes (PBL), thoracic duct lymphocytes (TDL), and those existing in the thymus, spleen and Peyer's patches were collected for analysis of subsets of T cells, helper/inducer T (Th) cells, suppressor/cytotoxic T (Ts) cells and B cells compared with those of the control group. In the PBL, differential and absolute counts of T and Th cells were lower in the group fed PSK (the PSK group) than the control group. There was no difference in Ts cells between the groups, and the PSK group showed a higher B-cell differential count. In the case of TDL, the PSK group showed greater absolute counts of T and Th cells than the control group. In tissue lymphocytes, differential T and Th cell counts were significantly greater in the PSK group than the control group, as observed first in Peyer's patches and later in the spleen. No differences between the groups were observed in these counts in the thymus. Changes in body distribution of T and Th cells induced by PSK treatment first appeared in lymphocytes in Peyer's patches, followed by PBL and TDL, and those in the spleen. No such changes were observed in the thymic lymphocytes.