Gamma-globulin inhibits tumor spread in mice

Intravenous (i.v.) lg is the human serum lg fraction that is mainly compose d of IgG prepared from plasma pools of over 15,000 healthy blood donors and is suitable for i.v. use. High-dose i.v. lg is currently used to treat pat ients with diverse autoimmune conditions. Autoimmunity and malignancy co-ex ist frequently, and share etiological and pathological mechanisms. Since th e two diseases are similarly treated, we studied the efficacy of i.v. lg as a treatment for malignant conditions. The administration of i.v. lg to mic e inoculated i.v. with melanoma or sarcoma cells induced a statistically si gnificant inhibition of metastatic lung foci and prolongation of survival t ime. Similar results were seen with SCID mice inoculated with SK-28 human m elanoma cells. In a different model, melanoma was induced in the foot pad, followed by leg amputation, after the development of the tumor lesion. A lo wer number of melanoma recurrences and prolongation of survival time were d emonstrated in the i.v. lg-treated groups. In vitro studies revealed that i .v. lg was found to stimulate the production of IL-12, an anti-tumor and an ti-angiogenic cytokine. Moreover, it enhanced NK cell activity, thus explai ning its beneficial effect in SCID mice (which lack B and T but possess NK cells). The results indicate that i.v, lg acts as an anti-tumor agent. Sinc e it has only minor side effects and is used extensively for other clinical conditions, i.v. lg may be considered as a potential therapy for the preve ntion of tumor spread in humans.