Thymic Dependency of Tumor-Induced Immunodepression

With hemolytic pleque techniques, splenic immune responses of varying degrees of thymic dependency were determined during mammary tumor growth in C3H/He mice, and histologic and gravimetric changes in lymphoid organs were described. After immunization with horse red blood cells, Escherichia coli lipopolysaccharide (LPS), or the hapten 4-hydroxy-3-iodo-5-nitrophenylacetic acid coupled to bovine γ-globulin, both 19s and 7s plaque-forming cells were measured. The effects of the adjuvant Bordetella pertussis were also examined. Depression during tumor growth increased with the degree of thymic dependency of the immune responses. The thymic-independent LPS response was not depressed, but strongly thymic-dependent responses were markedly reduced. We concluded that the immunodepressive effects of tumor growth were mediated through someaspect of T-cell function.