ELISA, protein immunoprecipitation and line blot assays for anti-TIF1-gamma autoantibody detection in cancer-associated dermatomyositis

OBJECTIVES

Anti-TIF1-gamma autoantibodies can be detected with immunoprecipitation (IP), line blot (LB) and ELISA. We compared assay performance in patients with DM and the potential of these assays to detect anti-TIF1-gamma positive cancer-associated DM (CADM).

METHODS

We included sera from 131 patients with DM followed at Karolinska University Hospital, Stockholm, Sweden and 82 healthy controls. Serum samples taken at DM diagnosis were tested for anti-TIF1-gamma autoantibodies with IP, two ELISAs (in-house and commercial) and LB. Cancer diagnosis and dates were obtained from the Swedish national cancer register. CADM was defined as a malignancy that developed within 3 years of DM diagnosis.

RESULTS

Anti-TIF1-gamma autoantibodies were detected in 19/101 (18.8%), 15/113 (13.2%), 34/131 (26%) and 45/131 (34.4%) of the patients with IP, LB, in-house and commercial ELISA, respectively. The anti-TIF1-gamma results from the in-house ELISA were confirmed with IP in 93 of 101 (92%) cases, κ = 0.76, with a commercial ELISA in 110 of 131 (84%) cases, κ = 0.63, and with LB in 101 of 113 (89.3%) cases, κ = 0.67. Anti-TIF1-gamma results with IP were confirmed with LB in 85 of 92 (92.4%) cases, κ = 0.73. For detecting CADM, the anti-TIF1-gamma in-house ELISA had a sensitivity of 58% and specificity of 86%, the commercial ELISA had a sensitivity of 63% and specificity of 82%, IP had a sensitivity of 52% and specificity of 92%, LB had a sensitivity of 40% and specificity of 96%.

CONCLUSION

The two anti-TIF1-gamma ELISA assays had advantages both for autoantibody detection and to identify anti-TIF1-gamma-positive CADM.

Percutaneous radiofrequency ablation of renal tumours: 29-month mean follow-up results of 118 patients

Background. Percutaneous radiofrequency ablation (RFA) is a minimally invasive method of treatment based on thermal effects. This retrospective study aimed to clarify percutaneous RFA of kidney tumors  –  performance, extremeness and 5-year survival in patients with small renal tumors in a single center. Materials and methods. Between September 2003 and December 2012, a total of 118 patients underwent percutaneous RFA of renal tumors. During more than 9  years period 144 RFA procedures were performed. Tumors were verified by biopsy. We used 3 RFA techniques: RFA under ultrasound control only (US), ultrasound guided RFA with CT navigation (US/CT) and ultrasound guided RFA with CT navigation, fiducial markers placed around the kidney tumor before the treatment (US/CT/FM). RFA electrodes were one and three. Patients were followed up regularly by CT with contrast enhancement. Results. The mean patient age was 68.72  years (range 28 to 86). The mean tumor size was 2.8 cm (range 1 to 5.4). The mean follow-up time was 29 months (1–111 months). Radical dependence on technical procedures: only US  39 (66.1%), US/CT 18 (94.7%), US/CT/FM 37 (92.5%), p = 0.001. Radical differences between using one and three electrodes: 39 (66.1%) and 55 (93.2%), p