Repeated treatment with S. aureus superantigens expands the survival rate of Ehrlich ascites tumor bearing mice.

The bacterial superantigen Staphylococcal enterotoxin-A (SEA), produced by some strains of Staphylococcus aureus, causes proliferation of cytotoxic T-lymphocytes and cytokine production in vivo. SEA has been shown to be highly efficient for antibody-targeted superantegen immunotherapy for different tumor models. A candidate B-cell superantigen that has received considerable attention these days is staphylococcal protein-A (PA). It has been shown to possess multiple immunological responses. The anti-tumor property of PA is well documented in the literature in various transplantable tumors of rats and mice. In the present study, we have shown that the T-cell superantigen SEA and B-cell superantigen PA induce immunomodulatory and anti-tumor activity which is strongly protentiated by PA + SEA co-administration. Combination treatment with PA and SEA prolongs the immune response in vivo, limits the development of immunological unresponsiveness and promotes maximum anti-tumor effects to tumor carrying animals, as compared with PA or SEA alone. The immune response after combined therapy is characterized by substantially augmented IFN-gamma, TNF-alpha, Nitric oxide and strong CTL activity. Our data demonstrate that combined PA + SEA therapy induces long-term survival of the animals, carrying the Ehrlich ascites tumor.