IS INTERLEUKIN-10 A GOOD OR A BAD CYTOKIN E IN A TUMOR CONTEXT

Tumors developed different ways of escaping immune recognition. The ab ility to release immunosuppressive factors directed against T lymphocy tes may be one mechanism of such escape. Interleukin 10 (IL10) has bee n proposed to be one of these factors, because of its potent immunosup pressive properties on cell-mediated immune responses. Moreover, if th e pattern of cytokine gene expression is analyzed within solid tumors, the IL10 gene is one of the most frequently expressed in many differe nt tumor types. This suggests that the IL10 secretion in a tumor micro environment may play a role in carcinogenesis by preventing an adequat e antitumoral immune response. Contrarily to what was hypothesized, th e transfer of the IL10 cDNA and its subsequent expression in mouse mel anoma cells result in a loss of their tumorigenicity in syngeneic mice . Moreover, a single vaccination with IL10 producing melanoma cells is able to protect the mice against a subsequent challenge with parental cells. Thus, in this tumor model, IL10 seems to be immunostimulatory rather than immunosuppressive, and has a surprising antitumoral activi ty. It remains to determine if this effect could be generalized to oth er tumor types and if IL10 is finally a factor favoring the escape of a tumor to the immune system or if it could increase the immunogenicit y of a tumor and help its rejection.