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Two AgNOR counts in fine-needle aspirates of lymphoproliferative disorders compared with acridine orange flow
W A Mourad1, R L Katz, D Sembera
1Department of Pathology Biomathematics, University of Texas, M.D. Anderson Cancer Center, Texas 77030.
Abstract:
Studies have shown that argyrophilic nucleolar organizer region-associated proteins (AgNORs) may correlate with DNA ploidy and/or proliferative activity in neoplastic and non-neoplastic conditions. However, studies have estimated only the mean AgNOR counts. Here we used two AgNOR counts, one of which may correlate with DNA ploidy and the other with proliferative activity. The mean AgNOR count (mAgNOR) was defined as the mean number of AgNORs/nucleus in 100 cells and may represent DNA or RNA index. The percentage of nuclei exhibiting 5 or more AgNORs/nucleus (pAgNOR) may reflect proliferative activity. These two AgNOR counts were correlated with results from acridine orange flow cytometry in 50 fine-needle aspirate (FNA) smears of nodal and extranodal sites, including three cases of reactive lymphadenopathy and 47 cases of non-Hodgkin's lymphoma. The mean mAgNOR count in the diploid specimens was 2.03 (+/- 0.74 SD) and 2.62 (+/- 0.73 SD) in the aneuploid tumors (P less than 0.0001). Samples with a low RNA index had mean mAgNOR of 1.80 (+/- 0.41 SD), whereas those with high RNA had a mean mAgNOR of 2.93 (+/- 0.86 SD) (P less than 0.0001). Lesions with low proliferative index, determined by flow cytometry, had a mean pAgNOR of 4%, whereas those with intermediate and high proliferative indices had a mean pAgNOR of 16% (P less than 0.0001). A similar but less significant correlation existed between RI and pAgNOR (P less than 0.005). We conclude that the two AgNOR counting methods may reliably reflect cell kinetics and distinguish ploidy from proliferative activity, making them useful adjuncts to flow cytometry in limited cytology specimens and small biopsy samples.
Insights
Two novel argyrophilic nucleolar organizer region-associated proteins (AgNORs) counts reliably distinguish cell ploidy and proliferative activity. These AgNOR methods offer valuable adjuncts to flow cytometry for analyzing small cytology and biopsy samples.
Area of Science:
- Cytopathology
- Oncology
- Molecular Biology
Background:
- Argyrophilic nucleolar organizer region-associated proteins (AgNORs) are linked to DNA ploidy and cell proliferation.
- Previous studies primarily focused on mean AgNOR counts, limiting detailed analysis.
- Novel AgNOR counting methods are needed to differentiate ploidy from proliferative activity.
Purpose of the Study:
- To evaluate two distinct AgNOR counting methods for their correlation with DNA ploidy and proliferative activity.
- To assess the utility of these AgNOR counts as adjuncts to flow cytometry in cytology specimens.
- To investigate the relationship between AgNOR counts and cell kinetics in neoplastic and non-neoplastic conditions.
Main Methods:
- Two AgNOR counts were analyzed: mean AgNOR count (mAgNOR) for DNA/RNA index and percentage of nuclei with ≥5 AgNORs (pAgNOR) for proliferative activity.
- Acridine orange flow cytometry was used to determine DNA ploidy and proliferative indices.
- The study included 50 fine-needle aspirate (FNA) smears from nodal and extranodal sites, encompassing reactive lymphadenopathy and non-Hodgkin's lymphoma.
Main Results:
- Mean mAgNOR counts significantly differed between diploid (2.03 ± 0.74 SD) and aneuploid tumors (2.62 ± 0.73 SD) (P < 0.0001).
- mAgNOR correlated strongly with RNA index (low RNA: 1.80 ± 0.41 SD; high RNA: 2.93 ± 0.86 SD) (P < 0.0001).
- pAgNOR showed significant correlation with proliferative index (low: 4%; intermediate/high: 16%) (P < 0.0001).
Conclusions:
- The mAgNOR count effectively reflects DNA ploidy and RNA index.
- The pAgNOR count serves as a reliable indicator of proliferative activity.
- These AgNOR counting methods are valuable adjuncts to flow cytometry for analyzing cell kinetics in limited cytology and biopsy samples.