Tumor-Specific Immunity Induced by Cryoablation in a Murine Renal Cell Carcinoma Model

PURPOSE: To evaluate tumor-specific immunity and define the mechanisms involved in the cryoimmunologic response, we compared the tumor control efficacy and immunologic responses of cryoablation with those of surgical excision in a tumor rechallenge model. MATERIALS AND METHODS: Sixty BALB/c mice with RENCA tumors that were generated in the left flank area underwent cryoablation or radical excision. The mice successfully treated were rechallenged with RENCA or an undifferentiated colon carcinoma cell line, CT26, in the contralateral right flank area. The recurrence rate after tumor rechallenge in each group was then observed. To assess the immunologic response of each treatment modality, fluorescent-activated cell sorting (FACS) analysis and a cytotoxicity assay using 51Cr release were performed. RESULTS: After reinoculation of the RENCA cells, the rate of tumor growth was significantly higher in the surgical excision group than in the cryoablation group (94.4% vs. 11.1%, p=0.001). In the cryoablation group, the tumor growth rate was significantly increased after rechallenge of CT26 cells compared with RENCA (94.1% vs. 11.1%, p=0.001). The cryoablation group showed an elevated CD3, CD4, CD8 T, and natural killer cell count in the FACS analysis and also showed significantly increased cytotoxicity in the 51Cr release assay compared with the excision group. CONCLUSIONS: These results showed that cryoablation, compared to surgical resection, was more effective in preventing tumor growth after rechallenge with RENCA cells and that this response was tumor-specific, because the CT26 cells did not have the same effect.

Frequency and clinical Importance of Anti - TG auto antibodies [ATG]

To note the frequency of anti thyroglobulin autoantibodies [ATG] and its clinical importance in 25 follow-up cases of differentiated thyroid cancer [DTC]. Design: A case control study. Place and Duration of Study: The total duration of study was one year [September 2000 to August 2001]. Majority of the patients included were the routine follow-up cases at IRNUM, Peshawar. However, few of the cases were also included from NORI, Islamabad and AFIP, Rawalpindi. Subjects and All the patients who had undergone sub-total or total thyroidectomy followed by I-131 ablation therapy were selected for this study. Thyroglobulin [Tg] and ATG were measured using immunometric assay technique with reference range of non-detectable to 40 IU/L. Patients with serum Tg level ' 10 ng/mL were included in group-1 [n=15] and all the remaining [n=10] in group-2. Overall, 11 patients showed ATG titer above the pre-defined threshold level. In group -1 patients, 8 had positive anti-Tg antibodies in their sera while in group-2, it was positive in only 3 cases. Risk of relapsing metastatic/recurrent disease in association with ATG was calculated which showed that patients with positive ATG have almost seven - fold increased risk of having recurrent/metastatic disease than those who do not. Samples for s-Tg measurements must also be evaluated for ATG status because more than one-third of these patients have positive ATG titer in their sera. Although in the presence of positive ATG, the risk of concurrent metastatic/recurrent thyroid disease is increased but still more studies are required to support its significance