Changes of peripheral T-cell subsets in asplenic W256 tumor-bearing rats

In exploring the mechanism of the effect of splenectomy on tumor growth, splenectomized rats and other control rats were implanted subcutaneously with Walker 256 carcinosarcoma cells (5 x 10(5] on day 10 after splenic operation; meanwhile, peripheral T-lymphocyte subsets were analysed successively. It was found that splenectomy enhanced the rate of tumor appearance and mean tumor diameter and disturbed the equation of T-lymphocyte subsets in peripheral blood, i.e., a subnormal level of Th/Ts ratio. Interestingly, a significant correlation was noted between decreasing values of Th/Ts ratio and increasing average diameters of implanted tumor in splenectomized rats, but not in sham-splenectomized or nonoperated rats with tumor growth. In spleen cells from tumor-bearing rats, a distinct increase of B-lymphocytes and a decrease of T cells were demonstrated. Data from this investigation provide striking evidence that a relationship exists between enhancement of tumor growth and disproportion of T-lymphocyte subsets in peripheral blood and offer some reasonable explanation for the causes of the promotive role of tumor growth following splenectomy.