Background and objectives: Cryogenic treatment sometimes stimulates the immune system by releasing intracellular antigens. We evaluated anti-tumor immune response by analyzing alterations in serum cytokine levels.
Methods: Percutaneous cryosurgery was performed in 13 patients with unresectable tumors. Serum levels of interleukin (IL) -4, -6, and -10, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma were measured by enzyme-linked immunosorbent assay (ELISA). The Th1/Th2 ratio was estimated from the IFN-gamma/IL-4 ratio.
Results: Levels of serum factors in the immune reaction (IR) group, in which tumor necrosis was identified not only in the treated area but also away from the treated area, were compared with those in the local effect (LE) group. Serum amyloid A (SAA), C-reactive protein (CRP), and IL-6 levels were increased in both groups after three treatments. The serum IL-10 level tended to increase with the number of treatments. Pretreatment IL-10 levels in the LE group were significantly greater than those in the IR group, and the maximum value in the LE group (59.5 +/- 13.2 pg/ml) was greater than that in the IR group (47.0 +/- 15.0 pg/ml). The TNF-alpha level was increased in the IR group. Pretreatment TNF-alpha levels and maximum levels in response to treatment were significantly greater in the IR group than in the LE group (P = 0.0313). The Th1/Th2 ratio was increased in the IR group, and the maximum ratio was significantly greater in the IR group than in the LE group.
Conclusion: It might be possible to evaluate the appearance of immune responses to cryosurgery by monitoring serum cytokine levels.
Copyright 2007 Wiley-Liss, Inc.