Different cutoff values for thyroid transcription factor-1 antibodies in the diagnosis of lung adenocarcinoma.

With the use of more specific treatments and targeted therapies for non-small cell lung carcinoma, distinction between adenocarcinoma (ADC) or squamous cell carcinoma (SCC) becomes increasingly important. For this, the key technique is an immunohistochemical panel in which a thyroid transcription factor-1 (TTF-1) antibody is often used. Two different TTF-1 clones (8G7G3/1 and SPT24) are used in daily practice, which appear to have different sensitivities and specificities. The aim of this study was to assess the differences between these clones and to identify the optimal cutoff value for correctly diagnosing primary or metastatic lung ADC. 182 pulmonary (109 lung ADCs, 62 lung SCCs, 11 lung metastases) and 115 extrapulmonary (36 metastatic lung ADCs, 79 nonpulmonary tumors) samples were stained with both TTF-1 antibodies. The percentage of tumor cells with nuclear staining was scored in categories of <1%, 1% to 5%, 6% to 25%, 26% to 50%, 51% to 75%, and 76% to 100%. The staining was further assessed as weak or strong. The sensitivity and specificity were calculated at different cutoff values. Applying the same cutoff value for positivity to both clones resulted in a significant difference between the clones at all cutoff values, with a lower sensitivity of 8G7G3/1 at high cutoff values and a lower specificity of SPT24 at low cutoff values. However, when the optimal cutoff value was used for each clone (>5% staining for 8G7G3/1 and >50% strong staining for SPT24), no significant difference in sensitivity (0.79 vs. 0.82) or specificity (0.98 vs. 0.98) was detected, making the clones equally useful for reliably diagnosing lung ADC.

Expression of the granzyme B inhibitor PI9 predicts outcome in nasal NK/T-cell lymphoma: results of a Western series of 48 patients treated with first-line polychemotherapy within the Groupe d'Etude des Lymphomes de l'Adulte (GELA) trials.

Nasal NK/T-cell lymphoma is a rare disease entity with a poor outcome. Expression of antiapoptotic proteins has not been extensively investigated in this entity. Forty-eight patients with nasal T/NK-cell lymphoma who received first-line polychemotherapy (n = 44) or chemoradiotherapy (n = 4) were analyzed for expression of active caspase-3 (aC3), granzyme B protease inhibitor 9 (PI9), and Bcl-2 proteins. Lymphomas were CD3+/CD5-/granzyme B+ and EBV-associated. Median age was 46 years. Stage I/II disease was present in 75% of the cases and an International Prognostic Index (IPI) score less than 1 in 65%. With a median follow-up of 6.3 years, 5-year event-free survival (EFS) and overall survival (OS) rates were 39% and 49%, respectively. Apoptotic index was scored as high in 32% of cases and PI9 expression as positive in 68%, whereas 35% disclosed a high number of aC3+ tumor cells. Univariate analysis showed that absence of PI9 and low apoptotic index were associated with poor outcome, but not aC3 expression nor IPI score. By multivariate analysis, both parameters affected independently EFS (P = .02 and .08, respectively) and OS (P = .009 and .04). In view of its constitutive expression by normal NK cells, it is suggested that loss of PI9 expression in tumor cells may reflect some mechanism associated with progression.

Hepatic natural killer cells exclusively kill splenic/blood natural killer-resistant tumor cells by the perforin/granzyme pathway.

Hepatic natural killer (NK) cells are located in the liver sinusoids adherent to the endothelium. Human and rat hepatic NK cells induce cytolysis in tumor cells that are resistant to splenic or blood NK cells. To investigate the mechanism of cell death, we examined the capacity of isolated, pure (90%) rat hepatic NK cells to kill the splenic/blood NK-resistant mastocytoma cell line P815. Cell death was observed and quantified by fluorescence and transmission electron microscopy, DNA fragmentation, and (51)Cr release. RNA and protein expression were determined by real time reverse transcription-polymerase chain reaction and Western blotting. Compared with splenic NK cells, hepatic NK cells expressed higher levels of perforin and granzyme B and readily induced apoptosis in P815 cells. Although P815 cells succumbed to recombinant Fas ligand (FasL) or isolated perforin/granzyme B, hepatic NK cells used only the granule pathway to kill this target. In addition, hepatic NK cells and sinusoidal endothelial cells strongly expressed the granzyme B inhibitor, protease inhibitor 9 (PI-9)/serine PI-6 (SPI-6), and P815 cells and hepatocytes were negative. Transfection of target cells with this inhibitor resulted in complete resistance to hepatic NK cell-induced apoptosis. In conclusion, hepatic NK cells kill splenic/blood NK-resistant/FasL-sensitive tumor cells exclusively by the perforin/granzyme pathway. Serine protease inhibitor PI-9/SPI-6 expression in liver sinusoidal endothelial cells may protect the liver microenvironment from this highly active perforin/granzyme pathway used to kill metastasizing cancer cells.