A ring trial to harmonize Toxoplasma gondii microsatellite typing: comparative analysis of results and recommendations for optimization.

A ring trial among five European laboratories was organized to reach consistency in microsatellite (MS) typing of the zoonotic parasite Toxoplasma gondii. Three sample sets were circulated and analyzed by each laboratory following a previously published method that is based on fragment length polymorphism of 15 MS markers. The first sample set compared typing results in general and focused on effects of DNA concentration; the second sample set focused on the polymorphic fingerprinting markers that can differentiate T. gondii strains within the same archetypal lineage; and the third set focused on non-archetypal genotypes. Methodological variations between laboratories, including the software programs used to determine MS fragment length, were collated using a questionnaire. Overall, lineage-level typing results reached a high level of agreement, especially in samples with the highest DNA concentrations. However, laboratory-specific differences were observed for particular markers. Major median differences in fragment length, of up to 6 base pairs, were related to the fluorophore used to label fragment-specific primers. In addition, primer pairs with identical sequences obtained from different suppliers resulted in fragments of differing length. Furthermore, differences in the way the sequencing profiles were assessed and interpreted may have led to deviating results in fragment length determination. Harmonization of MS typing, for example, by using the same fluorophores or by numerical adjustments applied to the fragment-lengths determined, could improve the uniformity of the results across laboratories. This is the first interlaboratory comparison, providing guidelines (added as a supplement) for the optimization of this technique.

MN/CA9: a potential gene marker for detection of malignant cells in effusions.

Many cancers cause malignant effusions. The presence of malignant cells in effusions has implications in diagnosis, tumour staging and prognosis. The detection of malignant cells currently presents a challenge for cytopathologists. New adjunctive methods are needed. Although the effusions provide excellent materials for molecular assay, the available molecular markers are extremely limited, which hinders its clinical application. MN/CA9 has proved to be a valuable marker in many cancers such as lung, breast, colon, kidney, etc. The present study was to evaluate MN/CA9 as a new molecular marker for the detection of cancer cells in pleural effusions. Seventy-one pleural effusions including 59 malignant effusions from patients with cancer, and 12 patients with benign diseases as a control, were subjected to RT-PCR for detection of MN/CA9 gene expression. MN/CA9 gene expression was detected in 53/59 (89.8%) pleural effusions from cancer patients (15/16 for breast cancers, 10/11 for lung cancers, 4/4 for ovary cancers, 2/3 for colon-rectal cancers, 5/6 for cancers of unknown site, 7/8 for mesothelioma and 10/11 for other cancers). Furthermore, MN/CA9 was positive in 13/18 (72.2%) of cytologically negative effusions of cancer patients. MN/CA9 was detected in only 1/12 (8.3%) effusions from the control patients (p < 0.01). The sensitivity and specificity of MN/CA9 gene expression were, respectively, 89.8% and 91.7%. Our preliminary results suggest that MN/CA9 could be a potential marker for the detection of malignant cells in effusions. A large-scale study is needed to confirm these results.

The expression of G250/mn/CA9 antigen by flow cytometry: its possible implication for detection of micrometastatic renal cancer cells.

Monoclonal antibody (mAb) G250 is a well characterized and specific mAb to renal cell carcinoma (RCC). The gene G250 was recently cloned and was proved to be homologous to MN/CA9. The G250/MN/CA9 antigen was recently explored as a potential marker for RCC. Flow cytometry (FCM) allows quantitative analysis of cells. The present study describes a flow cytometric method to detect this antigen in human cell lines and in malignant and normal renal tissues. Twelve human carcinoma cell lines (HeLa, Colo205, HT29, BxPC3, OVCAR3, SKOV3, ACHN, A704, CAKI-2, SKRC-59, SKRC-10, and SKRC-52), 10 specimens of normal peripheral blood mononuclear cells, and 38 malignant and 36 adjacent normal renal tissues were studied. The malignant and normal renal tissues were disaggregated mechanically into a single-cell suspension, stained by mAb G250, and analyzed by FCM. All 22 of the clear cell carcinomas, 6 of 8 mixed cell carcinomas, and 3 of 6 granular cell carcinomas were positive for G250/MN/CA9 antigen. SKRC-52 and SKRC-10 were strongly positive for G250/ MN/CA9. The G250/MN/CA9 antigen could also be detected in HeLa, SKOV3, HT29, and A704 cells. One chromophobic, one chromophilic cell carcinoma, the normal renal tissues, and normal peripheral blood mononuclear cells were considered as negative. Our results further confirmed that the G250/MN/CA9 antigen was an ideal marker for RCC, especially for clear cell carcinomas, and that this antigen was present in several types of malignant cells. FCM may serve as a fast tool of immunocytochemical detection of renal cancer cells. Flow cytometric detection of renal cancer cells by using mAb G250 should be further explored.

Flow cytometric analysis of antigen expression in malignant and normal renal cells.

UNLABELLED: Flow cytometry allows quantitative analysis of cancer cells. The aim of this study was to make a quantitative study of antigen expression in malignant and normal renal cells in order to find the efficient monoclonal antibodies (mAbs) for labelling renal cancer cells. MATERIAL AND METHODS: 15 malignant and adjacent normal renal tissues and three renal carcinoma cell lines (ACHN, A704 and CAKI-2) were analyzed. The malignant and normal renal tissues were dissociated mechanically into cell suspension. The mAbs and isotype controls were used for immunochemical labelling. The stained cells were analyzed by flow cytometry. RESULTS: Renal tumor associated antigen G 250 was frequently detected in malignant renal cells but not in normal renal cells. Renal tumor associated antigen gp200 recognized by 66.4.C2 and PN-15 was frequently detected in malignant cells, normal renal cells and also in all three carcinoma cell lines. Epithelial antigens were strongly positive in normal renal cells. Compared with MOC 31, Ber-EP4 and E 29, W-lD9 was mostly reactive to malignant renal cells. VU-1D9 was strongly positive on ACHN and A704. The carbohydrate carcinoma antigens CA 125, DF3 and Sialyl Lewis(a) were detectable in some of the malignant and normal renal cells. Sialyl Lewis(a) could be weakly detected on ACHN and A 704. Pan-cytokeratins and cytokeratin (CK) 8 were strongly expressed in malignant and normal renal cells and in all three cell lines. CONCLUSION: Our results indicated that G 250, 66.4.Ca, PN-15, VU-1D9, MNF116 and anti-ckg were efficient mAbs for labelling renal cancer cells. Their potential clinical application by flow cytometry should be explored.