Flow cytometry: methodology and applications in pathology

A Guide to Flow Cytometry: Components, Basic Principles, Experimental Design, and Cancer Research Applications

Flow cytometry (FCM) is a state-of-the-art technique for the qualitative and quantitative assessment of cells and other particles' physical and biological properties. These cells are suspended within a high-velocity fluid stream and pass through a laser beam in single file. The main principle of the FCM instrument is the light scattering and fluorescence emission upon the interaction of the fluorescent particle with the laser beam. It also allows for the physical sorting of particles depending on different parameters. A flow cytometer comprises different components, including fluidic, optics, and electronics systems. This article briefly explains the mechanism of all components of a flow cytometer to clarify the FCM technique's general principles, provides some useful guidelines for the proper design of FCM panels, and highlights some general applications and important applications in cancer research. © 2023 Wiley Periodicals LLC.

A flow cytometric journey into cell cycle analysis

Cell cycle involves a series of changes that lead to cell growth and division. Cell cycle analysis is crucial to understand cellular responses to changing environmental conditions. Since its inception, flow cytometry has been particularly useful for cell cycle analysis at single cell level due to its speed and precision. Previously, flow cytometric cell cycle analysis relied solely on the measurement of cellular DNA content. Later, methods were developed for multiparametric analysis. This review explains the journey of flow cytometry to understand different molecular and cellular events underlying cell cycle using various protocols. Recent advances in the field that overcome the shortcomings of traditional flow cytometry and expand its scope for cell cycle studies are also discussed.

Flow cytometry: principles, applications and recent advances

Flow cytometry (FCM) is a sophisticated technique that works on the principle of light scattering and fluorescence emission by the specific fluorescent probe-labeled cells as they pass through a laser beam. It offers several unique advantages as it allows fast, relatively quantitative, multiparametric analysis of cell populations at the single cell level. In addition, it also enables physical sorting of the cells to separate the subpopulations based on different parameters. In this constantly evolving field, innovative technologies such as imaging FCM, mass cytometry and Raman FCM are being developed in order to address limitations of traditional FCM. This review explains the general principles, main applications and recent advances in the field of FCM.

Applications of flow cytometry in molluscan immunology: Current status and trends

Flow cytometry (FCM) is routinely used in fundamental and applied research, clinical practice, and clinical trials. In the last three decades, this technique has also become a routine tool used in immunological studies of molluscs to analyse physical and chemical characteristics of haemocytes. Here, we briefly review the current implementation of FCM in the field of molluscan immunology. These applications cover a diverse range of practices from straightforward total cell counts and cell viability to characterize cell subpopulations, and further extend to analyses of DNA content, phagocytosis, oxidative stress and apoptosis. The challenges and prospects of FCM applications in immunological studies of molluscs are also discussed.

Reduction of relative centrifugation force within injectable platelet-rich-fibrin (PRF) concentrates advances patients' own inflammatory cells, platelets and growth factors: the first introduction to the low speed centrifugation concept

Purpose

The aim of this study was to analyze systematically the influence of the relative centrifugation force (RCF) on leukocytes, platelets and growth factor release within fluid platelet-rich fibrin matrices (PRF).

Materials and methods

Systematically using peripheral blood from six healthy volunteers, the RCF was reduced four times for each of the three experimental protocols (I–III) within the spectrum (710–44 g), while maintaining a constant centrifugation time. Flow cytometry was applied to determine the platelets and leukocyte number. The growth factor concentration was quantified 1 and 24 h after clotting using ELISA.

Results

Reducing RCF in accordance with protocol-II (177 g) led to a significantly higher platelets and leukocytes numbers compared to protocol-I (710 g). Protocol-III (44 g) showed a highly significant increase of leukocytes and platelets number in comparison to -I and -II. The growth factors’ concentration of VEGF and TGF-β1 was significantly higher in protocol-II compared to -I, whereas protocol-III exhibited significantly higher growth factor concentration compared to protocols-I and -II. These findings were observed among 1 and 24 h after clotting, as well as the accumulated growth factor concentration over 24 h.

Discussion

Based on the results, it has been demonstrated that it is possible to enrich PRF-based fluid matrices with leukocytes, platelets and growth factors by means of a single alteration of the centrifugation settings within the clinical routine.

Conclusions

We postulate that the so-called low speed centrifugation concept (LSCC) selectively enriches leukocytes, platelets and growth factors within fluid PRF-based matrices. Further studies are needed to evaluate the effect of cell and growth factor enrichment on wound healing and tissue regeneration while comparing blood concentrates gained by high and low RCF.

A comparative study of cell proliferation markers in breast carcinomas

Aims-To investigate the tumour cell proliferative index obtained by immunostaining of paraffin wax sections of 30 cases of breast carcinoma with monoclonal antibodies MIB1, KiS1 and KiS5, and polyclonal Ki67 antisera to the Ki67 antigen and 19A2 and PC10 antibodies to proliferating cell nuclear antigen and the possible correlation between these indices and that of monoclonal Ki67 antibody in frozen sections of the same tumours.Methods-All tumour samples had been uniformly fixed and processed and sections were subjected to microwave antigen retrieval before immunostaining in all instances except for monoclonal Ki67 antibody which was used in cryostat sections. Tumour cell proliferative indices were evaluated by two independent examiners, each counting 500 tumour cells with the aid of a cross-hatched grid.Results-Proliferative indices obtained with MIB1, polyclonal Ki67, KiS1, and KiS5 correlated with those obtained with monoclonal Ki67 in frozen sections. Proliferative indices obtained with monoclonal 19A2 and PC10 showed no correlation with those of monoclonal Ki67 antibody. The staining obtained with MIB1 was the most intense and the easiest to read.Conclusions-Monoclonal antibodies MIB1, KiS1 and KiS5 and polyclonal Ki67 antiserum appear to be suitable substitutes for monoclonal antibody Ki67 in the assessment of tumour cell proliferative index. As these reagents are all immunoreactive in paraffin wax sections, they overcome the requirement for frozen tissue for immunostaining with monoclonal Ki67.

Ki-67 expression gives additional prognostic information on St. Gallen 2007 and Adjuvant! Online risk categories in early breast cancer

BACKGROUND

We sought to determine the significance of Ki-67, one of the tumor cell proliferation markers, as a useful prognostic factor in early breast cancer.

METHODS

A total of 1080 consecutive patients with stage I or II breast cancer that underwent surgery between 1998 and 2003 were enrolled. Patients were categorized on the basis of the 2007 St. Gallen consensus and Adjuvant! Online. The expression of Ki-67 in the tumor was assayed by immunohistochemistry (cutoff value, 10%).

RESULTS

Univariate analysis determined that tumor size, lymph node involvement, histologic grade, estrogen receptor, progesterone receptor, bcl-2, and Ki-67 (> or =10%) were statistically significant for both overall survival (OS) and distant metastasis-free survival (DFS). Of these factors, lymph node involvement and high Ki-67 expression were identified as independent prognostic factors for OS and DFS on the basis of multivariate analysis. The survivals of intermediate- and high-risk groups according to 2007 St. Gallen consensus were further separated by Ki-67 expression level (5-year DFS rate = 91.9% vs. 86.3% for Ki-67 < 10% and > or = 10%, respectively in intermediate-risk group (P = .01); 5-year DFS rate = 82.5% vs. 61.4% for Ki-67 < 10% and > or = 10%, respectively in high-risk group (P = .01)). The survivals of low- and high-risk groups according to Adjuvant! Online were further separated by Ki-67 expression level (5-year DFS rate = 97.8% vs. 89.5% for Ki-67 < 10% and > or = 10%, respectively in low-risk group (P = .02); 5-year DFS rate = 9.4% vs. 82.6% for Ki-67 < 10% and > or = 10% in high-risk group (P = .005)).

CONCLUSIONS

Ki-67 is an independent prognostic factor for DFS and OS in early breast cancer and can provide additional prognostic information on the risk stratification with the use of the 2007 St. Gallen consensus and Adjuvant! Online.

Étude du contenu en ADN nucléaire dans les nodules thyroïdiens

Thyroid nodules are frequent and sometimes they pose a diagnostic and prognostic problem. DNA ploidy study and cell cycle analysis could be of value in the distinction between benign tumors and malignant tumors. Formalin-fixed and paraffin-embedded tissues from 69 patients with different benign and neoplastic lesions were investigated. Nuclear DNA content in thyroid cells was measured after Feulgen staining using SAMBA 200 image analysis system. A diploid DNA stemline was revealed in 75% of histologically proven benign thyroid tumors (15/20) and aneuploidy was found in 57.2% of malignant tumors (28/49). There is a significant correlation between aneuploidy and extra-thyroid extension (p=0.007) and bilateral and/or mediastinal lymph node metastasis (p=0.02). In the majority of benign tumors (19/20), the proliferation index was lower than 3% (< or =3%) however, this index value was higher than 3% (>3%) in more than 83% of malignant tumors (41/49) (p<0.001). The S phase fraction analysis revealed that the threshold of 14% divide the near whole of benign and malignant tumors (p<0.001). Our findings show that in follicular lesions, proliferation index and S phase fraction study appears interesting and helpful in the distinction between benign and malignant tumors, and aneuploidy seems more interesting in prognosis evaluation of these tumors.

Ki-67 expression in breast carcinoma: its association with grading systems, clinical parameters, and other prognostic factors--a surrogate marker?

BACKGROUND

The number of mitoses and, thus, the proliferative capacity of a tumor is one of the most crucial variables for tumor grading. The Ki-67 nuclear antigen may be considered as an alternative to mitotic counts in grading schemes and as a single parameter that can be used in fine-needle aspirates and small biopsies.

METHODS

Immunohistochemistry using the anti-Ki-67 antibody MIB-1 was performed on 434 breast carcinoma specimens from the International Breast Cancer Study Group (formerly Ludwig) Trial V. Three groups based on Ki-67 percent were used to replace the mitotic counts component in the Nottingham grade (NHG) to produce the Nottingham/Ki-67 grade (NKG) and to assess Ki-67 as a single parameter.

RESULTS

In both the lymph node positive subgroup and the lymph node negative subgroup, the NKG and Ki-67 group was correlated significantly with Bloom-Richardson grade (BRG), NHG, and Nottingham type. Tumor size in the lymph node negative cohort and estrogen receptor status, progesterone receptor status, and c-erbB-2 expression in the lymph node positive cohort also were correlated significantly with NKG. Ki-67 percentage was correlated significantly with c-erbB-2 expression in the lymph node positive cohort only. NKG was similar to BRG and NHG when it was evaluated for prognostic significance. Patients with higher categoric Ki-67 percentages had worse overall and disease free survival in all groups except for the untreated, lymph node negative group.

CONCLUSIONS

Ki-67 detection represents a valuable tool and is a good objective substitute for mitotic counts when used in a grading system. When it is used alone, Ki-67 detection provides valuable information, although it is necessary to combine this with other parameters in the study of core biopsies and fine-needle aspirates.

Application of flow cytometric techniques to veterinary clinical hematology

Flow cytometry has emerged as a major new technology in veterinary clinical laboratories. Flow cytometers in current use include stand-alone instruments and cytometers incorporated into hematology analyzers. Flow cytometers offer rapid and quantitative analysis of a variety of cell types based on cell size, molecular complexity, and antigenic composition. Therefore, flow cytometry complements and extends knowledge that can be obtained by light microscopy. Stand-alone instruments are very flexible, however, this flexibility opens the instrument to obtaining invalid or misleading results. The recent development of monoclonal antibodies specific for epitopes on blood cells of food and companion animals has greatly expanded the spectrum of tests with potential clinical application. Tests that appear to have the greatest potential for routine application include reticulocyte and reticulated platelet enumeration, detection of erythrocyte-bound immunoglobulin, immunophenotyping of leukemias and lymphomas, and bone marrow differential cell counting. This report will briefly review the technical aspects of flow cytometry and then focus on techniques with present or potential application to the veterinary clinical laboratory.

Cell proliferation and tumors of the central nervous system, part II: radiolabeling, cytometric, and immunohistochemical techniques

A variety of techniques have been developed to evaluate cell proliferation. Many of these methods provide a more accurate means of assessing the true proliferation rate of a given neoplasm, as compared with the simple assessment of mitotic activity. Similar to the evaluation of mitotic activity, these methods are also subject to limitations associated with tumor heterogeneity and interobserver variability. This paper reviews a variety of methodologies including radiolabeling, flow cytometric, and immunohistochemical that have been used in recent years to evaluate cell proliferation in brain neoplasms. Factors that affect these methodologies and their practical application to routine practice of diagnostic neuropathology will be explored.

The study of the process of fluid-phase endocytosis in cervical squamous cells using fluorescent microspheres

Physiological processes in cervical squamous epithelium have not been extensively studied. Perhaps understandably, most of the research has concentrated on the pathology of the cervix, in particular dysplasia and malignancy. Fluid-phase endocytosis is a physiological process which has been demonstrated to be important in understanding disease development at other squamous epithelial sites, e.g. oesophagus. In this study, we have demonstrated by a new methodology developed in our laboratory using fluorescent microspheres and flow cytometry that fluid-phase endocytosis occurs in cervical squamous cells. The process has been shown to be dose- and time-dependent. This novel approach provides a means to improve our understanding of the physiological functions of the cervix and may provide insight into the pathogenesis of cervical neoplastic and non-neoplastic disease.

Prognostic value of ploidy, cell proliferation kinetics, and conventional clinicopathologic criteria in patients with colorectal carcinoma: a prospective study

PURPOSE

The aim of this study was to obtain additional biologic determinants that may be of use in segregating into subgroups with different prognosis patients with similarly staged colorectal cancers.

METHODS

Between 1989 and 1991, a prospective study of prognostic factors has been performed in a group of 98 consecutive, unselected patients who underwent curative resections for primary untreated large bowel carcinoma. The fate of all patients is known at three years after operation. Clinical and pathologic data were recorded at the time of presentation and operation, and patients have been the subjects of regular follow-up. Tumor DNA content was determined by flow cytometry, and cell proliferative activity was determined by autoradiography with tritiated thymidine labeling index (LI).

RESULTS

Univariate analysis revealed that the most important predictors of survival (P < 0.001) were the presence of positive lymph nodes, the presence of preoperative complications, Dukes stage, and LI. The multivariate analysis showed that Dukes stage (P < 0.002) and LI (P < 0.0001) were the only factors significantly related to survival. Disease-free survival was influenced significantly by Dukes stage (P < 0.001), LI, according to the classification in the two groups of high and low proliferative activity, respectively, (P < 0.0001), LI, calculated as a continuous variable (P < 0.0002), and the presence of lymph node metastases (P < 0.003). Outcome (favorable/unfavorable) was influenced significantly by Dukes stage (P < 0.0001) and LI (P < 0.0001). Concordance for each patient between Dukes stage and outcome was 73.1 percent and between LI, calculated as a continuous variable, and outcome was 74.1 percent. If, on the other hand, Dukes stage and LI are used together, concordance with outcome reaches 89.2 percent.

CONCLUSION

We can conclude that, from a practical point of view, LI is an essential factor that must be combined with pathologic variables for a better prediction of patient outcome.

c-erbB-2 oncoprotein in relation to DNA ploidy and prognosis in colorectal adenocarcinoma

Overexpression of the c-erbB-2 oncogene has been demonstrated in a variety of tumours, including colorectal tumours. In breast carcinoma, c-erbB-2 overexpression is associated with DNA ploidy, some other prognostic indicators, and unfavourable survival prospects. However, there is little such information available regarding colorectal tumours. In this study, c-erbB-2 was analysed retrospectively by immunohistochemistry in 293 primary colorectal adenocarcinomas to assess its relation to DNA ploidy, S-phase fraction, other prognostic factors, and patient survival. Using the monoclonal antibody NCL-CB11, we found that 23% of the tumours were strongly c-erbB-2 positive, while 36% showed weak expression. The highest frequency of c-erbB-2 expression was 81% in DNA tetraploid tumours, compared to 63% in aneuploid and, 53% in diploid tumours (test for heterogeneity, p = 0.031). Overexpression of c-erbB-2 indicated a favourable prognosis in patients with DNA aneuploid tumours (p = 0.0088), but not in those with diploid or tetraploid tumours. The prognostic value of c-erbB-2 in DNA aneuploid tumours remained even after adjustment for Dukes' stage (p = 0.027). The results suggest that a combination of c-erbB-2 expression and DNA ploidy may improve the identification of patients' risk of cancer death.

Flow cytometry in the diagnosis of cancer

Flow cytometry has rapidly expanded from basic research to clinical laboratories mainly due to its unique characteristics regarding cell analysis. Among the clinical uses of flow cytometry cancer represents one of the most relevant. Several applications of flow cytometry can currently be applied to the study of cancer, including the detection of tumour cell DNA aneuploidy, the analysis of tumour cell proliferation and the immunophenotyping of leukemias. Although standardized flow cytometry protocols for these applications are scanty, the clinical value has been clearly established. The presence of DNA aneuploidy and a high proportion of S-phase tumour cells have been associated with tumour malignancy and a poor prognosis. The immunophenotype of leukaemia is of great help both for the diagnosis and classification of chronic lymphoproliferative disorders and acute leukaemias, especially in acute lymphoblastic leukemia cases and the M0, M3-variant, M6 and M7 acute myeloblastic leukaemia subtypes. In addition, it allows the identification of relatively rare leukemia cases such as the biphenotypic and the Nk-cell lineage leukemias. The development of flow cytometry is continuously bringing new applications into the clinical laboratory in the area of cancer diagnosis.

Which proliferation markers for routine immunohistology? A comparison of five antibodies

AIMS

To determine the best of five antibodies for immunohistochemical assessment of growth fraction in formalin fixed, paraffin wax embedded tissues.

METHODS

Sections from 100 recent, and 17 ten year old or over wax embedded blocks of normal and malignant tissues were immunostained with monoclonal Ki67, polyclonal Ki67, PC10, MIB1, and JC1. The antibodies were evaluated for specificity of nuclear versus cytoplasmic staining, cleanliness of background, and compared with the expected pattern of staining in normal tissues, defined immunohistochemically by monoclonal Ki67 antibody in frozen tissues or by tritiated thymidine uptake.

RESULTS

No marker was ideal, but best results were obtained with MIB1 and polyclonal Ki67, followed by JC1, PC10, and monoclonal Ki67.

CONCLUSIONS

For routine use, MIB1 or polyclonal Ki67 are the best proliferation markers in conventional histological preparations. The other markers tested cannot be recommended.

Prognostic value of flow cytometric deoxyribonucleic acid index in endometrial carcinoma: comparison with other clinical-pathologic parameters

OBJECTIVE

The aims of the current study were to verify the impact of flow cytometric deoxyribonucleic acid index on clinical outcome in endometrial carcinoma and to assess whether its value is independent from the other clinical-pathologic features.

STUDY DESIGN

In a prospective series 74 cases of endometrial carcinoma with surgery performed at our institution were studied. Flow cytometry was performed on fresh tumor samples. The median follow-up period was 31 months (range 8 to 52). Disease-free survival and actuarial survival were the end points of the study.

RESULTS

Among the 74 patients (53 with diploid and 21 with aneuploid tumors) there were 14 recurrences and 10 deaths caused by the disease. The recurrence rate was 7.5% for the diploid and 47.6% for the aneuploid tumors (p < 0.001). Mortality was 3.8% for diploid and 38% for aneuploid cases (p < 0.001). Disease-free survival was 89.1% in the former group and 36.3% in the latter. Actuarial survival (Kaplan-Meier method) was 94.7% and 49.5%, respectively. Deoxyribonucleic acid index, stage (International Federation of Gynecology and Obstetrics), and grade of differentiation were significantly correlated with survival, whereas age, depth of myometrial invasion, and histologic type were not. In a multivariate analysis (Cox proportional hazards) deoxyribonucleic acid index was the strongest independent predictor of clinical outcome, followed by International Federation of Gynecology and Obstetrics stage, whereas grade of differentiation yielded no independent prognostic information.

CONCLUSIONS

The flow cytometric deoxyribonucleic acid index is an important independent prognosticator, and its determination should be included in the standard management of endometrial cancer.

Analysis of DNA aneuploidy and c-myc oncoprotein content of canine plasma cell tumors using flow cytometry

To derive a method for determining malignant potential of plasma cell tumors, a retrospective analysis of the DNA ploidy and relative p62c-myc oncoprotein content using bivariate flow cytometry was performed on 23 formalin-fixed, paraffin-embedded tissues from 23 dogs. The samples included one tissue each from 17 males and six females 2 to 16 years of age (mean = 7.5 years). Twelve breeds were represented, including three Cocker Spaniels, three Golden Retrievers, and five of mixed breed. Ten of the samples were histologically classified as malignant-plasma cell tumors, and ten specimens were classified as benign. Three samples of plasmacytic inflammation, from two Cocker Spaniels and one Shih Tsu, were included as controls. The ploidy and relative c-myc content data obtained were compared with the histologic grade. A significant difference in ploidy was found between benign and malignant tumors (P < or = 0.05). Five of nine malignant plasma cell tumors were aneuploid; the remainder were diploid (4/9) or tetraploid (1/9). Only one of the benign plasmacytomas was aneuploid (1/10), whereas six were diploid (6/10), and three were tetraploid (3/10). All of the controls were diploid (3/32). When relative amounts of p62c-myc from malignant and benign tumors were compared by flow cytometry, a greater significant difference was established (P < or = 0.01) than bu using aneuploidy alone. Relative values of p62c-myc content ranged from 219 to 553 units in 8/10 malignant plasma cell tumors and from 86 to 392 units in 3/10 benign plasmacytomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of a monoclonal antibody (IND.64) identifying a cell cycle-associated antigen using spleen cells from nude mice bearing Ichikawa tumour

Using spleen cells from athymic nude mice grafted with Ichikawa tumour, we have generated the monoclonal antibody IND.64, which detects a proliferation-associated nuclear antigen. Immunoblotting analysis with IND.64 showed a double band with apparent molecular weights of 395 and 345 kD. In normal human tissues, the antigen detected by IND.64 was expressed only by the nuclei of proliferating cells, such as germinal centre cells of reactive lymph nodes, cortical thymocytes, the basal layer of the skin, and proliferative compartments of the stomach, small intestine, and colon. IND.64 did not react with cells known to be non-proliferative or to show only a low turnover, such as cells of the kidney, liver, smooth muscle, cardiac muscle, and brain. The expression of this antigen during the cell cycle was determined using two approaches: IND.64 immunostaining of synchronized adult bovine aortic endothelial cells and flow cytometric analysis of double-labelled PHA-stimulated peripheral mononuclear blood leucocytes with a DNA marker and IND.64. The antigen recognized by IND.64 was found to appear in the late G1 phase, and persisted in phases S, G2, and M, but was absent in the G0 and early G1 phases. IND.64 was further investigated in different tumour types to evaluate the correlation between the percentage of IND.64-positive cells (IND.64 index) and the histological grade. In non-Hodgkin's lymphomas, an excellent correlation was found between the percentage of IND.64-positive cells and the cytomorphological grade. In nodular sclerosis and mixed cellularity Hodgkin's disease, a high number of Reed-Sternberg cells were positive with IND.64. The non-lymphoid neoplasms investigated showed a variable percentage of positive cells. IND.64 appears to be a promising tissue marker to complement the evaluation of prognosis in human cancer.

Flow cytometry of oesophageal mucosal biopsies; epidermal growth factor receptor, and CD15

Flow cytometry may be used to examine the properties of single or isolated cells. We have shown that it is possible to disaggregate and label oesophageal epithelial cells for two surface markers, CD15 and epidermal growth factor receptor. We have previously demonstrated these markers in oesophageal squamous cells using immunoperoxidase techniques. These labelled disaggregated cells could then be measured by flow cytometry.

DNA ploidy in squamous oesophageal carcinoma

The role of DNA ploidy in the management of oesophageal carcinoma is unclear. Most studies have employed flow cytometry (FC) for DNA analysis but some have used image analysis (IA) of tissue sections. In this study aneuploidy rates in stage IIa squamous tumours were determined by both FC and IA of cell suspensions and results were compared with outcome in two patient subgroups. Group 1 (n = 15) were patients who died from tumour recurrence within 1 year of surgery while Group 2 (n = 21) were patients who survived tumour free for at least 1 year. Aneuploidy rates differed significantly between techniques; 29 of 36 tumours (81%) were aneuploid by IA compared with 19 of 34 (56%) by FC (P < 0.05). Aneuploidy rates differed significantly between groups 1 and 2 as determined by FC (79%) versus 40%) (P < 0.05) but not by IA (93% versus 71%) (P = ns). Euploid status was a good prognostic indicator; 6 of 7 (86%) patients with euploid tumours by IA and 12 of 15 (80%) by FC (P < 0.05) survived more than 1 year. The sensitivity and specificity of euploidy was 93% and 28.6% for IA compared with 78.6% and 60% for FC. Since 33 (92%) of these tumours exhibited a marked peritumoral desmoplastic or chronic inflammatory reaction IA, being more sensitive to subtle nuclear change, may be a more appropriate technique than FC for evaluation of the role of ploidy in such tumours.

Flow-cytometric analysis of growth-regulatory peptides and their receptors in Barrett's oesophagus and oesophageal adenocarcinoma

The conventional assessment of the premalignant potential of Barrett's oesophagus is unsatisfactory. However, it has recently been shown that abnormalities of growth-regulatory peptides and their receptors may be important in the pathogenesis of this condition. In an attempt to improve the diagnostic and prognostic criteria we have studied 21 consecutive patients with Barrett's oesophagus and 7 others with adenocarcinoma of the oesophagus. In each patient biopsy specimens were taken from the columnarlined oesophagus or the adenocarcinoma and from the gastric cardiac mucosa for routine histologic evaluation. Immediately adjacent specimens were taken from both the Barrett's mucosa or adenocarcinoma and from the gastric mucosa for flow-cytometric study. The latter samples were disaggregated and labelled with antibodies to epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R). The flow cytometer selected cells labelled with each antibody and expressed them as a percentage of the total number of disaggregated cells (average, 5500 cells). Epidermal growth factor receptors were expressed in a greater number of cells from Barrett's mucosa, with the intestinal type or those with dysplasia, than in gastric cardiac mucosa (p less than 0.05). All seven adenocarcinoma had many more cells expressing EGF, TGF-alpha, and EGF-R than normal gastric mucosa (p less than 0.01). We conclude that flow-cytometric evaluation of EGF-R can help in the understanding of the pathogenesis of Barrett's oesophagus.

Cellular glutathione (GSH) and glutathione S-transferase (GST) activity in human ovarian tumor biopsies following exposure to alkylating agents

In vitro studies have suggested that elevated levels of the thiol glutathione (GSH) may be associated with acquired alkylating agent resistance, but there is currently little data on the relationship between elevated GSH and glutathione S-transferase levels and clinical alkylating agent resistance. In this study, GSH and glutathione S-transferase levels have been determined in 23 human ovarian tumor samples obtained prior to the onset of combination chemotherapy, and in 23 samples obtained after the development of acquired chemoresistance. GSH levels were 10-fold greater in human ovarian tumor cells obtained after alkylating agent resistance developed, than in biopsy samples obtained prior to treatment. No significant changes in the expression of total glutathione S-transferases were seen in relation to prior drug exposure.

A comparative study of proliferation indices and ploidy in dysplastic naevi and malignant melanomas using flow cytometry

Cell proliferation indices and DNA content have been determined in 18 intradermal naevi, 40 dysplastic naevi and 16 superficial malignant melanomas (less than 0.76 mm depth of invasion) using flow cytometry. In this study, proliferation indices of intradermal naevi and dysplastic naevi were not significantly different from each other. Abnormalities of DNA ploidy were not identified in the intradermal naevi or dysplastic naevi; whereas three of the malignant melanomas were aneuploid. In addition, cellular proliferation was increased within the group of malignant melanomas, in comparison with the naevi. This study has found no evidence to indicate that sporadic dysplastic naevi were more likely than intradermal naevi to transform to malignant melanoma, when objective criteria were employed. However, dysplastic naevi could be distinguished from some early malignant melanomas by absence of aneuploidy and by low cell proliferation indices.

Histopathological evaluation of oesophageal carcinoma: the significance of venous invasion

Follow-up data on 115 patients who had undergone surgical resection for oesophageal carcinoma were analysed. Histological sections were reviewed for tumour classification, grading and staging, and special stains were used to detect venous invasion. The effect of various factors on survival was statistically analysed using Cox's proportional hazards regression model. In this multivariate analysis lymph node metastasis was the most important variable in the assessment of survival (improvement chi 2 = 7.43, P = 0.006). Venous invasion, which was demonstrated with a frequency of 76.5 per cent (mostly intramural) was the second most important prognostic factor (improvement chi 2 = 2.86, P = 0.09). The relative risk for the presence of both variables was rather modest (3.09).

Determination of proliferating fractions in malignant melanomas by anti-PCNA/cyclin monoclonal antibody

An immunohistochemical study of melanocytic tumours using 19A2, a monoclonal antibody against proliferating cell nuclear antigen (PCNA/cyclin), was performed on tissues routinely processed with formalin fixation and paraffin embedding. In normal skin, keratinocytes of the suprabasal region in epidermis, the papillae and outer root sheath of hair follicles and the basal cells lining the lobules of sebaceous glands were stained in the nucleus. Other skin components, including basal and follicular melanocytes, did not demonstrate nuclear labelling. In addition, expression of PCNA/cyclin in keratinocytes was higher in sun-exposed skin compared with unexposed skin. In melanocytic lesions, PCNA/cyclin positive tumour cells increased in number and staining intensity according to the following progression: common melanocytic naevi; dysplastic naevi; primary melanomas; and metastatic melanomas. Expression of PCNA/cyclin, therefore, provides a useful marker for proliferation and tumour progression in skin.

Monoclonal antibody Ki-67: its use in histopathology

Monoclonal antibody Ki-67 is a reliable and easy means of accurately assessing the growth fraction of human neoplasms. Although the number of long-term follow-up studies is limited, it does appear to provide valuable prognostic information particularly in lymphoproliferative disease. Since the estimation of growth fraction is only one factor influencing tumour behaviour it would be naive to believe that measurement of this parameter alone, no matter how accurately, would provide the clinician with definitive prognostic information for all tumours. The antibody is also of use in research, providing a means of measuring proliferative activity in a variety of conditions besides malignancy, and may prove of value in monitoring tumour response to established and trial therapies.

Correlation between in vitro tetraploidy in skin fibroblasts and development of sporadic colorectal carcinomas

In vitro tetraploidy (IVT) in skin fibroblasts cultures measured by flow cytometry was compared with histological type and degree of dysplasia in 22 patients with adenomas of the colon and rectum. Furthermore, IVT was compared with stage and differentiation in 36 patients with carcinoma of the colon and rectum. In vitro tetraploidy in skin fibroblasts was correlated to type as well as dysplasia in adenomas and differentiation in carcinomas but was not correlated to Dukes' stage in carcinomas. Skin fibroblast genetic instability, expressed as increased IVT (IVT+), has been reported to reflect a genetic predisposition to colorectal cancer in the hereditary nonpolyposis colorectal cancer syndrome. Because IVT+, which appears to be associated with the progression of adenomas to carcinomas, also is found in many of the non-syndrome colorectal cancers, we suggest that development of colorectal cancer is considerably influenced by the constitutive genetic instability of the autosomal dominant colorectal cancer syndromes.

Immunoproliferative small intestinal disease: a study of 13 cases with alpha heavy-chain disease

The pathology of 13 cases of immunoproliferative small intestinal disease (IPSID) associated with alpha-heavy-chain disease--one an apparent non-secretor and another with localized infiltration--is described. Four cases exhibited immunohistological light-chain monotypia. In one of these, evolution of a light-chain negative cell population was observed over a 7-year period. In the intestine, centrocyte-like cells produced lympho-epithelial lesions in 11 cases and enlarged lymphoid follicles in three. In lymph nodes, perifollicular infiltration was observed in 11 cases and abnormal follicles in six. Of three patients with high-grade lymphoma at presentation, one died untreated at 2 months, and two are alive at 34 and 91 months. Of 10 patients with low-grade disease at presentation, two died--one at 76 months, the other after transforming to high-grade lymphoma at 73 months. Eight patients with low-grade disease are alive, an average of 67 months after presentation. Four of five conservatively treated low-grade cases (including three in remission) showed evidence of monoclonality at presentation (light-chain monotypia in two and gene rearrangement in two), while two of the five exhibited DNA aneuploidy. It is concluded that IPSID with alpha-heavy-chain disease is neoplastic in all its stages and is a variant of mucosa-associated lymphoma. The role of centrocyte-like cells and the response to conservative therapy are discussed.

Ploidy of smooth muscle tumours: retrospective image analysis study of formalin fixed, paraffin wax embedded tissue

The feasibility of using an image analyser, the CAS 100, to assess the ploidy of smooth muscle tumours on formalin fixed paraffin wax embedded tissue was assessed. Various different methods of assessment were compared. A paraffin wax block of 15 leiomyomata and 13 leiomyosarcomata yielded serial sections of 3 microns, 5 microns, and 7 microns and a cytospin preparation (from a 50 micron section). Sections and cytospin preparations were stained with Feulgen and quantified using the CAS 100. The suitability of lymphocytes, previously suggested to be unsuitable as control cells in tissue sections due to the compact nature of their DNA, was assessed in sections and cytospin preparations and compared with endothelial cells, the standard alternative, on the same slide. Despite having a mean nuclear area of only 18.5 microns 2 in sections lymphocytes had a similar diploid peak--that is, 4.1 pg--to endothelial cells (mean nuclear area 39 microns 2). A comparison of 3 microns, 5 microns, and 7 microns sections showed 5 microns to be the optimal thickness. Cytospin preparations yielded histograms of superior quality than those from tissue sections. All 15 leiomyomata had a 5C exceeding rate of less than 0.3%. Ten of 11 histologically malignant tumours had a 5C exceeding rate of more than 5% (mean 14%) in sections and cytospins. Two leiomyosarcomata that had arisen in the lower gastrointestinal tract had a mitotic rate of less than or equal to 1/10 per high power fields and yielded histograms similar to those of the leiomyomata. It is concluded that formalin fixed, paraffin wax embedded tissue can be used for DNA quantification by image analysis; that tissue sections yield poorer results than cytospin preparations; that lymphocytes are reliable control cells in cytospin preparations; and that a population of cell greater than 5C is seen in 90% of leiomyosarcomata.

Cytophotometry in tumor pathology. A critical review of methods and applications, and some results of DNA analysis

In tumor pathology the quantitation of cellular substances can be of diagnostic value. Microscope cytophotometry and digital image analysis and, on the other hand, flow cytometry are supplementary methods for measuring, each with a typical spectrum of application. The methods are predominantly used for DNA analysis: Static and image cytophotometry are applicable to cytologic and histologic slides preferably for identifying stem lines in tumors of heterogenous morphology and in merely circumscribed lesions (e.g., precancerous lesions). On the other hand, sampling errors due to preselection, and the often low number of cells actually measured, may preclude the possibility of exact cell cycle analysis. This is, in fact, an important additional option of flow cytometry resulting from the high resolution of DNA histograms, which is explained by the large number of cells that can be measured in a short period. Sampling errors in flow cytometry may result from the preparation of single cell suspensions which in certain tumor entities may suppress a varying amount of particularly fragile cells or nuclei. The prognostic significance of DNA ploidy, stem line heterogeneity and S-phase fraction is clearly described in quite a number of tumor entities. Independent of its prognostic value, the cytometric identification of stem lines might be particularly useful in the follow-up of tumor patients, where it may indicate the effectivity of systemic therapy. The development of therapeutic concepts is aptly supported by flow cytometric cell cycle analysis which helps to assess the in vitro effect of combined cytostatics on the proliferative process. Moreover, multiparameter analysis of biopsy samples may provide greater accuracy in characterising individual tumor stem lines and may furthermore help to develop improved protocols for the therapy of solid tumors.

Comparison of flow cytometry and retrospectively applied static cytometry on lymphoid tissue

Twenty cases of non-Hodgkin's malignant lymphoma were examined using both flow cytometry (FCM) and static cytometry (SCM) DNA analysis to detect aneuploidic cell populations. FCM was performed on fresh cell suspensions whilst SCM was performed retrospectively on formalin-fixed, paraffin-embedded samples of the same tissue. A total of 34 aneuploidic cell lines were detected by FCM compared to a total of 41 detected by SCM. Of the 20 cases 14 showed DNA indexes within 10% of each other for each method, indicating a reasonable degree of comparability between the two methods. Of the 6 cases which did not show comparable DNA indexes, 2 displayed similar cell lines for both methods, but the major abnormal cell populations were of different ploidy by SCM as compared to FCM. A qualitative comparison is thus possible between these two cases. The results suggest that retrospectively applied SCM ploidy analysis of lymphoid tissue is comparable to FCM on fresh tissue samples and can thus be used in retrospective studies of both prognostic and diagnostic significance.

DNA in human glioblastomas. A flow-fluorescence cytometrical examination of 96 tumors

The Flow-Fluorescence Cytometric Method (FCM) was applied to investigate the DNA content and the ploidy outlines of each of 96 glioblastomas. No specific DNA pattern was detected, possibly because of the tangle morphology of these variable tumors. Due to their capricious growth the DNA distribution proved to fluctuate greatly. Thus, the series, arranged according to increased PI (proliferation index) values, exhibited a wide spread within a total range from 7.1-97.15% (mean 39.3%) PI. A threefold subdivision of main types (I-III) appears to be of practical use for clinical prognostic assessment: "diploid" tumors with a PI range up to 10% (N = 7) are followed by "abnormal" chiefly tetra- and hyper-tetraploid tumors up to PI values about 30% (N = 21). The third category includes cases showing excessive "aneuploidy" combined more and more with polyploidy and valid stemlines, up to the PI maximum of about 97 rel.% (N = 68). Thus, in 89 tumors clear pathological changes of DNA content can be decoded; of these 68 (76.4%) express a considerable aneuploidy and polyploidy respectively.

Flow cytometric detection of multifocal DNA aneuploid cell populations in mastectomy specimens containing a primary breast carcinoma

DNA flow cytometry was used to study the presence of DNA aneuploid cell populations in macroscopically normal glandular tissue in mastectomy specimens from 30 patients with breast cancer. In the 13 patients with a DNA diploid primary tumor, no DNA aneuploidy could be found in any of the 39 distant specimens assessed. However, DNA aneuploid cell populations were demonstrated in four of the 17 (23%) patients with a primary DNA aneuploid carcinoma and in seven out of 54 (13%) distant tissue samples (P = 0.02). In all cases the DNA index of the DNA aneuploid cells found in the distant samples was identical to that of the primary tumor. The replicate aneuploid DNA indices and histologic controls taken in parallel very strongly suggest that these distant DNA aneuploid cell populations are metastases.

DNA in chordomas of the clivus Blumenbachi

Chordomas of the clivus are frequently denoted as malignant, mainly because of their propensity to recur, their crucial location and the fatal clinical course. Although microscopical examination commonly reveals pleomorphism, particularly of cells and nuclei, the histological assessment of malignancy is not always appropriate. The measurement of DNA could provide important information for a classification of their biological behavior (grading). Our examination of a chondroid chordoma revealed a typical diploid DNA curve within a "benign" 4C range concordant to the favorable course of this variant. Our second examination of a "typical" chordoma showed a wide pleomorphism of cell nuclei and moderate proliferation activity within a "low grade" scale. This pointed to a coming (fatal) recurrence 3.5 years after the first surgery. The third chordoma we examined presented an extraordinary 4C aneuploidy with hypertetraploid subpopulations and an increased number of bi- or poly-nucleated tumor cells with prominent nucleoli and some more mitotic figures. In 5 recurrences the DNA pattern remained principally unchanged.

Prognostic value of nucleolar organizer regions and ploidy values in advanced colorectal cancer

The prognostic value of nucleolar organizer regions and ploidy status in patients with Dukes' C colorectal cancer was determined. In addition, nucleolar organizer regions and ploidy status were compared with the established prognostic indices age, sex, tumour location and degree of histological differentiation. Fifty-one patients (27 men, 24 women) aged 35-81 years (median 64.8 years) were studied. Five years after presentation, 16 patients were alive and well. Survivors had significantly lower nucleolar organizer region counts (median value and range) in primary tumours 12 (8-15) and lymph node metastases 11 (8-15) than non-survivors 17 (14-25) and 18 (13-25) respectively (P less than 0.05). Fewer survivors had aneuploid tumours than non-survivors: four survivors compared with 17 non-survivors. In a regression analysis model, nucleolar organizer regions were the most important individual variable for predicting survival (chi2 = 15, P less than 0.01) while ploidy values (chi2 = 6, P less than 0.2) were equivalent to histological differentiation.

Ploidy as a prognostic indicator in oesophageal squamous carcinoma and its relationship to various histological criteria

One hundred surgically resected squamous cell carcinomas of the oesophagus were studied retrospectively to assess the significance of DNA aneuploidy as determined by flow cytometry using paraffin-embedded tissue. DNA aneuploidy was not an independent prognostic indicator but was found to be associated with tumour necrosis and host/tumour interface fibrosis. When tumours confined to submucosa or muscle wall were assessed, diploid tumours had a poorer survival rate than DNA aneuploid tumours. Other histological variables studied were tumour differentiation, depth of infiltration, glandular and small cell differentiation, lymphatic and vascular spread and host inflammatory response. These failed to show any significant association with ploidy.

Abnormal DNA content in liver-cell dysplasia: a flow cytometric study

To clarify the true nature of liver-cell dysplasia (LCD), a flow cytometric study has been performed. The DNA content of hepatocytes from 26 cases of cirrhosis with diffuse areas of LCD was investigated and compared to that of hepatocytes from 21 control patients with non-neoplastic and neoplastic liver conditions. Flow cytometric analysis was performed on propidium-stained nuclei from archival paraffin-embedded material. Analysis was directed to assessment of diploid as well as non-diploid peaks by calculation of DNA index (DI), using normal hepatocytes present in each sample as individual and specific references. Since only samples containing at least 10,000 nuclei were considered suitable for analysis, 4 of the 26 LCD cases were discarded. Eight of 22 LCD cases had an abnormal DNA content compared with 0/11 non-neoplastic cases (p less than 0.05) and 8/10 hepatocellular carcinomas (p less than 0.05). Non-neoplastic control cases displayed uniformly diploid stemlines whereas hepatocellular carcinomas had in 8/10 cases bimodal or trimodal populations. Thus, LCD is a heterogeneous lesion in terms of ploidy, and the abnormal DNA content observed in some cases supports its pre-neoplastic nature.