Ehrlich ascites tumour unbalances splenic cell populations and reduces responsiveness of T cells to Staphylococcus aureus enterotoxin B stimulation

Tumours must avoid host immune response to survive and proliferate; to achi eve this purpose, tumours interact with cells of the immune system by means of tumour secreted factors. The alterations of splenic cell populations in mice bearing the Ehrlich ascites tumour have been studied. A rapid and acu te response was observed, characterized by a decrease in both CD4 and CD8 T cells, and a transient increase in the number of B cells, which peaked 2 d ays after tumour inoculation. An increase in macrophage population and in t he homing antigen CD18 was also detected. In vitro incubations of splenic c ells with the Staphylococcus aureus enterotoxin B (SEB) showed that tumour induces a state of reduced responsiveness to stimulation of T cells, mainly affecting CD8 T cells, and a diminished IFN-gamma expression. (C) 2000 Els evier Science B.V. All rights reserved.