The binding affinity of polyoma-tumor specific antigen (TSTA) to receptors of lymphocyte populations.

The incorporation of 3H-thymidine was used as a means to determine the stimulation of thymus and lymph node cell populations by TSTA obtained and purified from the surface of polyoma cells in a conditioned medium with T cell growth factor. The specificity of TSTA was demonstrated after the immunization of CBA mice in adoptive transfer of lymph node cells followed by challenge with polyoma cells. The binding affinity of TSTA to receptors of lymph node cells and thymocytes from CBA mice was tested by radiolabelling. Differences in binding affinity estimated on the basis of equilibrium constant (K) and maximal binding capacity (n) were found between thymus and lymph mode cells populations but not between lymph node cells populations themselves. The lack of change in the binding affinity of 125I-TSTA to receptors of lymph node cells in various experimental mice was also discussed.