There is a growing body of literature surrounding the specific functions of HMGB1 on cells of the immune system as well as its role in important disease states. As the mechanisms promoting the release of HMGB1 and the signaling pathways it activates remain to be completely elucidated, evidence that suggests its potential as a therapeutic target/agent in various models of inflammation continues to accumulate. Importantly, human-subject studies which demonstrate its elevation in several disease states further indicate its importance. Interestingly, in addition to its proinflammatory roles, HMGB1 also appears to have several regenerative effects that lead to tissue repair. Understanding HMGB1 and its complex effects on the immune system may lead to the development of novel strategies to attenuate inflammation and/or promote tissue repair and regeneration in various clinical states. Quantitative measurement of thyroglobulin mRNA in peripheral blood of patients after total thyroidectomy Previous studies have reported the clinical usefulness of reverse transcription-polymerase chain reaction (RT-PCR) detection of thyroglobulin (TG) mRNA in the peripheral blood of patients with differentiated thyroid carcinoma. To evaluate this usefulness, we measured TG mRNA in the peripheral blood of patients diagnosed with thyroid carcinoma after total thyroidectomy by real-time quantitative RT-PCR using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA as an internal control. Surprisingly, we detected TG mRNA in all samples obtained after total thyroidectomy, including those from 4 medullary carcinomas. Further, there was no statistical difference in expression levels of TG mRNA in the patients with or without metastasis, and no significant correlation was found between serum TG concentrations and the expression levels of TG mRNA. These results give rise to a question regarding the clinical applications of not only RT-PCR detection but also quantitative measurement of TG mRNA in peripheral blood. © 2001 Cancer Research Campaign http://www.bjcancer.com Thyroid carcinomas often recur many years after surgery (Loh et al, 1997) . The monitoring of serum thyroglobulin (TG) by immunoassay can be used in detecting residual or recurrent differentiated thyroid carcinoma (DTC) after total thyroidectomy. However, the usefulness of this method is limited by both the requirement for thyroid hormone withdrawal to attain optimal sensitivity and interference by antithyroglobulin antibodies (Singer et al, 1996) . Recent reports have demonstrated that the reverse transcription-polymerase chain reaction (RT-PCR) can be used to detect circulating cancer cells in the peripheral blood of patients with malignancies such as prostate cancer (Ghossein et al, 1995) and neuroblastoma (Mattano et al, 1992) .