Induction of apoptosis in tumor cells as a mechanism of tumor growth reduction in allergic mice

Cancer is the leading cause of mortality worldwide. Analysis of epidemiological data has revealed a negative relationship between allergic conditions and cancer incidence. This study addresses the effects of chronic antigen ingestion by sensitized mice (allergy) on Ehrlich tumor growth in mouse footpad. Mice were sensitized (allergic) or not (sham) with ovalbumin and challenged orally with egg white solution. After one week of oral challenge, all mice were inoculated with experimental Ehrlich tumor (EET) cells in the footpad, and tumor growth was evaluated for 21 days. A decrease in tumor growth occurred, as assessed by paw thickness in the allergic group, which was associated with smaller areas of necrosis, reduced infiltration of neutrophils, and reduced levels of IFN-gamma, IL-4, and IL-10. Although, the tumor proliferation rate was similar in both groups, an increase in apoptosis occurred in allergic mice. In conclusion, analysts of the data obtained allows its to suggest that a concomitant allergic condition would reduce tumor progression through increased tumor cell apoptosis, accompanied by reduced areas of necrosis at the tumor site. Indeed, such findings suggested a possible mechanism for the reduced cancer incidence observed in allergic individuals. (C) 2009 Elsevier GmbH. All rights reserved.