Immunocytochemical evaluation of the percentage of proliferating cells in pathological bone marrow and peripheral blood samples with the Ki-67 and anti-bromo-deoxyuridine monoclonal antibodies

BrdU incorporation in multiparameter flow cytometry: A new cell cycle assessment approach in multiple myeloma

BACKGROUND

Mutiple myeloma (MM) is a neoplasia characterized by the accumulation of malignant plasma cells (PC) in the bone marrow. Although proliferation markers have been studied in MM, none of the current staging systems include them. Moreover, approaches used to analyze proliferation do not separate MM cells (MMCs) from normal PC.

METHODS

In this study, we combined multiparameter flow cytometry and BrdU incorporation or Ki67 staining to analyze MM cell proliferation in 44 monoclonal gammopathy of undetermined significance (MGUS), 153 newly diagnosed MM patients and 69 MM patients at relapse. The prognostic value of proliferation assessment was analyzed in 60 newly diagnosed patients treated with high-dose chemotherapy supported by autologous hematopoietic stem cell transplantation.

RESULTS

The median number of proliferating malignant PC significantly increases during MM disease progression. MM patients with a percentage of proliferating MMCs greater than 1.42% using BrdU/DAPI or greater than 1.1% using ki67/DAPI, are associated with a significantly shorter event free survival compared with patients with a lower percentage of proliferating MMCs.

CONCLUSIONS

Combination of flow cytometry with BrdU or ki67/DAPI staining could become a standard for the determination of MM cell proliferation. Furthermore, in the context of new effective myeloma treatment options, assessment of MM cell proliferation may be valuable, in clinical trials, to identify novel agents that could significantly affect the small proliferative compartment of MM cells. © 2018 International Clinical Cytometry Society.

Histology and immunohistology of bone marrow biopsy in multiple myeloma

B5-fixed/paraffin-embedded Jamshidi needle biopsies from 125 multiple myeloma patients were reviewed according to both morphological and immunohistological criteria. At microscopic examination, the following parameters were evaluated: i) grade of malignancy (low = 56; intermediate = 50; high = 19); ii) growth pattern (interstitial +/- sheets/nodules = 90; nodular = 13; packed marrow = 18; sarcomatous = 4); III) histological stage (I = 64; II = 35; III = 26). Comparison of the findings in trephine biopsies and aspirates showed that in 30% of the cases the latter led to an underestimation of the tumor burden. Immunohistochemical determination of Ig easily allowed: i) differential diagnosis from exuberant reactive plasmacytosis; ii) recognition and counting of neoplastic plasma cells; iii) detection of minimal residual disease after treatment. Immunohistochemistry also confirmed phenotypic aberration of neoplastic plasma cells, showing positivity for CD45, EMA, and cytokeratins in 14%, 59%, and 25% of the cases, respectively. Furthermore, it displayed expression of the P-glycoprotein in 4/8 resistant cases. These findings underline that routinely processed Jamshidi needle biopsies can be of great value in the study of patients with multiple myeloma.

Plasma cell growth fraction using Ki-67 antigen expression identifies a subgroup of multiple myeloma patients displaying short survival within the ISS stage I

The current most powerful prognostic model in Multiple Myeloma (MM) combines beta-2 microglobulin (b2m) with albumin, corresponding to the International Staging System (ISS). However, the prognosis of patients within the ISS stage I (high albumin and low b2m) may vary. Ki-67 is a nuclear protein associated with cell proliferation. We retrospectively evaluated the percentage of bone marrow plasma cells expressing Ki-67 antigen (Ki-67 index) in a series of 174 untreated MM patients at diagnosis. Median survival was 51, 41 and 20 months respectively, and median Ki-67 index was 3.0%, 6.1% and 6.5% in ISS stages I, II, and III respectively. Independently of ISS, Ki-67 index > or =4% was highly predictive of adverse prognosis. Ki-67 index correlated with markers of intrinsic malignancy and with markers of tumour burden. Within ISS stage I, median survival was of 31 months (RR of death 2.65) in patients with Ki-67 index > or =4%. Eventually, the combination of Ki-67 with b2m produced an efficient prognostic model, which appeared most effective in our series when compared with b2m and KI-67 with chromosome 13 deletion models. In this series, we demonstrated that a proliferation marker provides clear-cut additional survival prognostic information to b2m into the ISS model.

Aberrant morphology, proliferation, and apoptosis of B-cell chronic lymphocytic leukemia cells

B-cell chronic lymphocytic leukemia (CLL) has been traditionally described as a disease characterized by an accumulation of quiescent small lymphocytes with decreased susceptibility to apoptotic cell death. However, small numbers of "atypical" lymphocytes and prolymphocytes (PL) are frequently observed in the bone marrow (BM) of patients with CLL. In this study, we examined BM biopsy and aspirate specimens obtained from seven patients with atypical CLL. Using a double labeling (Ki-67+/CD20+) immunohistochemical method, we found that an appreciable number of the atypical CLL cells expressed the proliferation-associated protein Ki-67. Because CLL is characterized by a slow change in the peripheral blood (PB) lymphocyte count, we reasoned that a subpopulation of CLL cells probably undergoes spontaneous apoptosis. Using Western blot analysis, we observed expression of procaspase-9, procaspase-10, and poly(ADP-ribose) polymerase by the neoplastic cells in all seven cases of CLL, and procaspase-3 and procaspase-8 expression in six neoplasms. We also detected cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase in four and five CLL cases, respectively. To determine whether CLL cells undergo spontaneous apoptosis, we performed the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay using BM biopsy specimens. We found TUNEL-positive lymphocytes in areas infiltrated by CLL. In summary, our data show that subpopulations of B-lymphocytes are proliferating or undergoing spontaneous apoptotic cell death in patients with atypical CLL.

Ki-67 Proliferation Index

The nuclear protein Ki-67 is a proliferation index, as it is expressed only by dividing cells. In this study, we investigated the clinical significance of Ki-67 determination on bone marrow biopsies of 35 patients with newly diagnosed multiple myeloma (MM). We examined the correlation of Ki-67 with other MM proliferation-related factors: interleukin-6 (IL-6), IL-10, bone marrow infiltration by plasma cells, serum lactate dehydrogenase (LDH), and beta 2 microglobulin (b2M). Ki-67 expression was also correlated with the survival rate of the patients. The results showed that Ki-67 expression increases with increasing stage of disease according to Durie-Salmon (classification stage III vs. I and II, p < 0.001). Furthermore, infiltration, IL-6, LDH, and b2M increase significantly with advancing stage of disease (p < 0.004). All parameters studied were significantly higher in patients versus controls. Ki-67 correlated with IL-6 (r: 0.422, p < 0.01), LDH (r: 0.437, p < 0.01), and b2M (r: 0.478, p < 0.004). There was a marked difference in survival between patients with MM with Ki-67 greater than 8% and patients with Ki-67 less than 8%, in favor of the latter (p < 0.07). We conclude that Ki-67 determination during routine pathological analysis of bone marrow in newly diagnosed MM could provide useful information about the proliferative activity and prognosis of the disease.

Cyclin D1 and E2F-1 immunoreactivity in bone marrow biopsy specimens of multiple myeloma: relationship to proliferative activity, cytogenetic abnormalities and DNA ploidy

Cyclin D1, encoded by the CCND1 gene, is immunohistochemically detectable in up to one-third of cases of multiple myeloma (MM). To examine the mechanism of cyclin D1 overexpression, we compared cyclin D1 immunoreactivity with the results of conventional cytogenetics to determine if the t(11;14)(q13;q32) or other abnormalities of 11q11-14 explained cyclin D1 overexpression. Karyotypic abnormalities were found in 45 out of 67 (67%) MM cases; the t(11;14) was present in seven cases (10%). Additional 11q11-14 abnormalities were not identified. The t(11;14) correlated with cyclin D1 upregulation in low to intermediately proliferative MM, but was not present in highly proliferative tumours (assessed using bromodeoxyuridine labelling index). Cyclin D1 indirectly activates the transcription factor E2F-1. In the bone marrow biopsy specimens of MM cases, E2F-1 was concurrently expressed with cyclin D1 (P = 0.001), indicating that cyclin D1 is functional. However, as neither E2F-1 nor cyclin D1 expression correlated with proliferative activity, the speculation that t(11;14) upregulates the CCND1 gene to induce higher proliferation and possibly more aggressive disease is not supported. We conclude that in low to intermediately proliferative MM cases, cyclin D1 is probably upregulated by t(11;14), but an alternative mechanism is more probable in highly proliferative MM.

Hepatic regeneration in humans with various liver disease as assessed by Ki-67 staining of formalin-fixed paraffin-embedded liver tissue

The ability to document nuclear proliferation in the liver is essential to our understanding of hepatic regeneration and hepatocellular carcinoma. While numerous tests are available to provide such information in experimental animals, few can be applied to patients with liver disease. Ki-67 is a proliferating nuclear antigen present in replicating cells. Recent data indicates that staining for Ki-67 reflects nuclear proliferation in these tissues. To date, the technique has had only limited application to human liver tissues in formalin-fixed paraffin embedded tissue. In the present study, we documented Ki-67 staining in archival liver tissue from patients with mild chronic hepatitis, severe chronic hepatitis, inactive cirrhosis, hepatocellular carcinoma, and in normal livers. We found that Ki-67 staining was increased in patients with mild chronic hepatitis (labelling index 29 +/- 25), severe chronic hepatitis (labelling index 41 +/- 40), and hepatocellular carcinoma (labelling index 71 +/- 61), when compared to patients with inactive cirrhosis, (labelling index 1.4 +/- 3.1), and normal livers (labelling index 2.5 +/- 3.2). In conclusion, Ki-67 maybe useful tool to assess hepatocyte proliferation in formalin-fixed paraffin-embedded human liver tissue.

The correlation of Ki-67 staining indices with tumour doubling times in regrowing non-functioning pituitary adenomas

In order to improve our ability to predict the regrowth of nonfunctioning pituitary adenomas, we tried to assess the correlation between growth fractions with Ki-67 and PCNA (proliferating cell nuclear antigen) and tumour doubling times in regrowing tumours, and also to find out any difference of growth fractions between the regrowing and the cured cases. In 33 patients with non-functioning pituitary adenomas, 14 cases including 11 with cavernous sinus invasion showed residual tumour on MRI after the operation (regrowing group) and 19 cases had no tumour regrowth on MRI within 5 years after the operation (cured group). Immunocytochemical studies were done with monoclonal antibodies (anti-PCNA, anti-Ki-67: MIB-1). The growth fraction of each tumour was estimated by calculating the ratio of the positive nuclei to the total number of tumour cells with the aid of an image analyser (Mac SCOPE). The tumour doubling times were estimated from serial CT or MRI with the aid of the image analyser (NIH image). Ki-67 staining indices ranged from 0.2% to 1.5% (n = 14, 0.86 +/- 0.10%; mean +/- SEM) in the regrowing group, and from 0.1% to 0.5% (n = 19, 0.23 +/- 0.03%) in the cured group. PCNA staining indices of the regrowing group ranged from 0.6% to 24% (n = 14, 3.7 +/- 1.6%). In the regrowing group, the tumour doubling times ranged from 200 to 2550 days (930 +/- 180 days), and showed a significant inverse correlation with Ki-67 staining indices, but no correlation with PCNA staining indices. The regrowing group showed a significantly higher Ki-67 staining index (n = 14, 0.86 +/- 0.10%) than the cured group (n = 19, 0.23 +/- 0.03%) (p < 0.01). These results indicate that immunocytochemical studies using MIB-1 may be better than those with PCNA for the prediction of regrowth in non-functioning pituitary adenomas. Immunocytochemical study with MIB-1 could lead to the accurate prediction of the rapid regrowing lesions in non-functioning adenomas.

Assessment of cell proliferation in normal and pathological bone marrow biopsies: a study using double sequential immunophenotyping on paraffin sections

The proliferative activity of the haematopoietic and plasma cells in bone marrow was evaluated under normal and neoplastic conditions, by means of a sequential double immunostaining technique, using monoclonal antibody MIB-1 recognizing the cell proliferation-associated nuclear antigen Ki-67, and antibodies against glycophorin-C, myeloperoxidase, factor VIII-related antigen, and immunoglobulin light chains. Fifty-eight B5 fixed, paraffin-embedded bone marrow biopsies were analysed, including 11 normal controls. 10 cases of myelodysplasia, 14 cases of chronic myeloproliferative disorder, eight cases of acute non-lymphoid leukaemia, and 15 cases of myeloma. In normal marrows, the highest proliferative activity was noticed in the erythroid cells (75% to 95%; mean 90%), in comparison with myeloid precursors (15% to 80%; mean 38%), and megakaryocytes (10% to 20%; mean 14%): no Ki-67 positive plasma cells were found. In all investigated haematological disorders, the expression of MIB-1 by erythroid cells was similar to that observed in controls. Similarly, the percentage of MIB-1 + myeloid precursors in chronic myeloproliferative disorders and myelodysplasia largely overlapped the values observed in normals, and comparable values were also found in the blast cells from acute non-lymphoid leukaemia type M1 and M2. These findings suggest that the evaluation of either erythroid or myeloid proliferative activity is of little value in the differential diagnosis between these myeloproliferative disorders. By contrast, the obvious increase of Ki-67 expression of megakaryocytes in chronic myeloproliferative disorders, with labelling also of micro-megakaryocytes, might sustain the diagnosis in controversial cases. Since cases of mature myeloma showed less than 2% of Ki-67 positive cells, evaluation of proliferative activity is of no value in the differential diagnosis with reactive plasmacytosis. The sequential double immunophenotyping for Ki-67 antigen and for haematopoietic cell lineage-associated markers can be applied in a consistent manner to routine bone marrow biopsies to evaluate proliferating cells in normal and neoplastic conditions.

Assessment of proliferative activity in leukaemic bone marrow using the monoclonal antibody Ki-67

AIMS

To investigate proliferative activity in leukaemic and lymphomatous bone marrow infiltrates and to assess the feasibility of transport of specimens among institutions.

METHODS

Proliferative activity in bone marrow trephine cryosections from 99 patients with non-Hodgkin's lymphoma (NHL), 23 patients with acute myeloid leukaemia (AML), 11 with acute lymphoblastic leukaemia (ALL), and two with acute undifferentiated leukaemia (AUL) was investigated. Infiltration was seen in 52 out of 99 cases of NHL on bone marrow cryosections. A score was devised to assess pathological infiltrates in bone marrow trephine cryosections using the monoclonal antibody Ki-67. This method of scoring gave a measure of non-erythroid proliferative activity.

RESULTS

Mean Ki-67 positivity in bone marrow infiltrates in 31 low grade B cell lymphomas (Kiel classification) was 0.3% before and 4.7% after treatment, 16.4% in seven high grade B cell lymphomas, and 17.8% in 12 peripheral T cell lymphomas. In 48 cases of NHL, bone marrow cryosections had not been infiltrated, and in all but one case the percentage of Ki-67 positive cells in normal marrow was less than 3%; the remaining case showed coexistent myelodysplasia and 8% bone marrow Ki-67 positivity. In eight cases of common ALL at diagnosis, the mean Ki-67 positivity in marrow cryosections was 24.9%, significantly higher than the 2.4% Ki-67 positivity seen in AML (p < 0.05). One of the two cases of common ALL with less than 1% Ki-67 positivity was refractory to treatment.

CONCLUSIONS

Proliferative activity of erythroid elements in the bone marrow varies greatly. Immunostaining of bone marrow cryosections using Ki-67 permits accurate assessment of non-erythroid proliferative activity in lymphomas and leukaemia. High grade B cell lymphomas and peripheral T cell lymphomas invading the marrow have very similar mean proliferative activities. Such levels of proliferation are of the same order as those seen in common ALL, but much higher than those seen in AML.

Hydrochloric acid denaturation of colorectal tumour tissue infiltrated with bromodeoxyuridine

The thymidine analogue, bromodeoxyuridine, is substituted into DNA during DNA synthesis and can be used to identify those cells which have passed through the S-phase of the cell cycle. Incorporated bromodeoxyuridine can be detected using anti-bromodeoxyuridine monoclonal antibodies which bind to the exposed bromodeoxyuridine in single-stranded DNA after a suitable denaturation step. Hydrochloric acid is the most commonly employed denaturation agent in bromodeoxyuridine monoclonal antibody methodologies. This preliminary study was to validate the hydrochloric acid denaturation step for colorectal tumour tissue infiltrated in vivo with bromodeoxyuridine. Standard immunohistochemistry and flow cytometric techniques using Bu20a were employed across a range of hydrochloric acid concentrations. Although high labelling indices were achieved using acid concentrations of 0.10 M HCl, the optimal hydrochloric acid concentration was not the same in all tumours. Sensitivity of DNA to hydrochloric acid denaturation should be carefully considered in bromodeoxyuridine methodologies using the monoclonal antibody Bu20a.

Expression of Ki-67 nuclear antigen in B and T cell lymphoproliferative disorders

AIMS

To determine whether the proliferation rates of tumour cells may relate to prognosis and reflect disease activity.

METHODS

Blood mononuclear cells from 155 patients with B cell (n = 120) or T cell (n = 35) chronic lymphoproliferative disorders were tested with the monoclonal antibody Ki-67 by indirect immunoperoxidase or immunoalkaline phosphatase techniques. B cell diseases included chronic lymphocytic leukaemia (CLL), CLL in prolymphocytic transformation (CLL/PL), prolymphocytic leukaemia (B-PLL) and non-Hodgkin's lymphoma (B-NHL) in leukaemic phase. The T cell diseases comprised large granular lymphocyte (LGL) leukaemia, T-PLL, and T-NHL.

RESULTS

These showed significantly higher proportions of Ki-67 positive cells in T cell (11.2%) than in B cell (2.9%) disorders (p < 0.001). The highest values were found in NHL of both B and T cell types, particularly when low grade disease transformed to high grade. The lowest percentages of Ki-67 positive cells were found in CLL (1.4%) and LGL leukaemia (1.7%); intermediate values were seen in B PLL (3.3%) and T PLL (5.8%).

CONCLUSIONS

There is a positive correlation between prognosis and proliferation rates in chronic B and T cell lymphoproliferative disorders. Estimation of Ki-67 in circulating leukaemic cells could be used to determine prognosis in low grade malignancies.

The assessment of cellular proliferation by immunohistochemistry: a review of currently available methods and their applications

Immunohistochemical methods using antibodies to cell cycle-related antigens may be used as a means of assessing various aspects of proliferation in tissue, and have the important advantage of preserving the spatial orientation of proliferating cells in histological sections. Currently, the most widely available antibodies for this purpose are antibodies to bromodeoxyuridine (BrdU), Ki67 and antibodies to proliferating cell nuclear antigen (PCNA). BrdU is a thymidine analogue incorporated during the S phase of the cell cycle, which can be introduced by 'in vitro' incubation, and monoclonal antibodies are available to display its localization. Ki67 demonstrates a nuclear antigen expressed in all phases of the cell cycle, except G0 and early G1, but can only be applied to frozen tissue. PCNA is a nuclear antigen which is essential for DNA synthesis, two commercially available antibodies to PCNA work in paraffin-embedded tissue, but may have different staining characteristics under different conditions of fixation. The main advantages and disadvantages of these different techniques are discussed, together with their main applications to date.

Cell proliferation in childhood acute leukemia. Comparison of Ki-67 and proliferating cell nuclear antigen immunocytochemical and DNA flow cytometric analysis

The proliferative activity of bone marrow leukemia cells was determined by DNA flow cytometric (FCM) analysis and labeling index (LI) of Ki-67 monoclonal antibodies and proliferating cell nuclear antigen (PCNA) autoantibodies in 73 children with acute leukemia. LI of Ki-67 varied greatly from patient to patient (range, 0.4% to 42.2%; mean, 18.8%) and differed significantly between acute lymphoblastic leukemia (ALL) and acute nonlymphoblastic leukemia (ANLL). In ALL, the Ki-67 LI showed a positive correlation with the S-phase fraction (SPF) determined by DNA FCM analysis, whereas, in ANLL, there was a discrepancy between the Ki-67 LI and SPF. In contrast, LI of PCNA varied less among the patients (range, 57.2% to 100%; mean, 90.3%), and the value was always higher than that of the Ki-67 LI in individual patients. A significant relationship between PCNA LI and the percentage of blast cells was found in peripheral blood leukocytes from patients with leukemia. These results suggest that the Ki-67 LI reflects differences in the proliferative activity depending on the subtype of the disease and that the PCNA LI is useful as a marker of proliferating cells.

The biological and clinical significance of the KI-67 growth fraction in multiple myeloma

We tested the significance of the Ki-67 plasma cell growth fraction in 49 bone marrow samples from 42 patients with multiple myeloma (MM). As a new approach to study myeloma cell proliferation, strong positivity of the CD38 antigen as plasma cell related feature was simultaneously evaluated with nuclear Ki-67 expression in a flow cytometric double immunofluorescence assay. Mean Ki-67 values were significantly higher in MM at relapse (22.4 per cent +/- 10.4) as compared with MM at diagnosis (11.9 per cent +/- 8.4, p less than 0.005) and plateau-phase (10.0 per cent +/- 5.5, p less than 0.001), respectively. Serial observations in six patients confirmed this change in cell kinetic behaviour during the course of the disease. Elevated Ki-67 values correlated significantly with stage III (versus stage I, p less than 0.05), beta-2-microglobulin serum levels greater than 6 (p less than 0.001), plasmablastic morphology (p less than 0.001), and diploid myeloma cell DNA-content (p less than 0.005). No correlation was found between Ki-67 and immunoglobulin isotypes as well as immunophenotypic features (expression of CD10, CD33, and CD56) of myeloma cells. Clinically, six of seven patients with Ki-67 greater than 14 per cent at diagnosis had an unfavourable course (primary resistant disease or early relapse), and three of four patients with elevated Ki-67 values at plateau-phase relapsed within 3 months. Our results demonstrate the usefulness of Ki-67 in determining proliferative activity in MM and emphasize its value in the evaluation of the risk profile of MM patients.

Relevance of Ki-67 expression in the classification of non-Hodgkin's lymphomas: a morphometric and double-immunostaining study

The proliferation of reactive and neoplastic cells was retrospectively assessed in 92 cases of non-Hodgkin's lymphoma by morphometry using a double-immunoenzymatic technique including surface markers and the monoclonal antibody Ki-67. The findings were compared with the histological diagnosis. The overall Ki-67 positivity is not always a good measure of the corresponding corrected values and therefore we recommend that a correction should be made for the total number of complementary lymphocytes in the tumour. Taking the macrophages and the Ki-67 positivity of the reactive cells into account does not generally add any information. There was no difference in reactive cell content between follicular (counted within follicles) and diffuse lymphomas within the tumour areas. The value of the group mean for low-grade follicular (nodular) lymphomas was significantly higher than that of diffuse low-grade lymphomas, but not significantly different from that of intermediate-grade lymphomas. High-grade lymphomas exhibited significantly greater Ki-67 positivity than those of intermediate grade. In 76% of the cases there was significant agreement between malignancy grade (low/intermediate malignant versus high malignant) at 45% corrected Ki-67 counts.

Nuclear and DNA-binding proteins in human brain tumors

Nuclear proteins obtained from human brain tumor cell lines by differential salt extraction were subjected to high-resolution two-dimensional electrophoresis. Several hundred spots were detectable in the low salt (0.4 M NaCl) extract using silver staining. These patterns exhibited remarkable differences between the different cell lines we analyzed. A less complex pattern occurred when nuclei were subsequently treated with high salt (2.5 M NaCl/5 M urea). We compared the electropherograms from various human glioblastoma cell lines and found them very similar and even a high degree of similarity occurs between glioblastomas and other human tumor cell lines. Beside these more general observations we detected several proteins at least enriched in human glioblastomas which were totally absent in low grade astrocytomas and nonglial tumors. They could be separated from the bulk of nonspecific proteins by simple modifications of the isoelectric focusing conditions. From these results we conclude that nuclear proteins obtained by sequential salt extraction and separated by two-dimensional techniques may provide tumor specific proteins suitable for antibody production.

Prognostic significance of the proportion of Ki-67-positive cells in adult T-cell leukemia

The authors examined peripheral blood samples from patients with adult T-cell leukemia (ATL) using the monoclonal antibody Ki-67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki-67-positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P less than 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki-67-positive cells and the length of survival (P less than 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki-67 (0.01 less than P less than 0.02). Thus, Ki-67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.

Ki-67 and bromodeoxyuridine labeling of human choroidal melanoma cells

Understanding tumor growth patterns has implications for prognosis as well as for response and susceptibility to treatment. The antibody Ki-67 was used as a marker of cycling cells and bromodeoxyuridine (BrdUrd) was used as a marker of proliferating cells to characterize the cycling and proliferative rates of cells from human choroidal melanoma. The BrdUrd labeling indices varied from 0-1.1% and the Ki-67 labeling indices ranged from 0-3.0.3%. Linear regression modeling showed good correlation defined by the equation: Ki-67 index = 0.237 + 1.63 x BrdUrd labeling index with r = 0.919. Correlations between these indices and clinical and histologic parameters were not significant.

Determination of proliferative activities in human brain tumor specimens: a comparison of three methods

Proliferative activities were determined in 72 human brain tumors, including 20 metastatic carcinomas, 41 gliomas, 8 meningiomas and 3 hematological tumors. Immunocytochemical techniques included labeling with monoclonal antibody (mAb) to bromodeoxyuridine (BrdU) which identifies S phase cells after previous in vitro BrdU incubation and paraffin embedding of fixed tissue specimens, and with mAb Ki-67 which reacts, in frozen sections, with a nuclear antigen expressed by all proliferating cells. BrdU labeling index (LI), Ki-67 LI and mitotic index (MI) correlated well with histological malignancy. Among the three proliferation indices, Ki-67 LI and BrdU LI were highly significantly correlated. With the exception of hematological malignancies, hyperbaric oxygenation of in vitro BrdU labeling did not significantly increase BrdU LI or depth of BrdU penetration into tissue. This study indicates that in vitro BrdU labeling is a useful alternative to Ki-67 immunolabeling of human brain tumor specimens. By such determination of tumor proliferation, it might be possible to design a more adequate postoperative therapy tailored to patients individually.

Modalities of synthesis of Ki67 antigen during the stimulation of lymphocytes

The antibody Ki67 is currently used to evaluate the proliferative fraction of solid tumors and some hematological malignancies. We have used phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes as a model to study the entry of quiescent cells into cell cycle and to follow their progress to the next cycle. Flow cytometric analysis of lymphocyte samples stained with the antibody Ki67 and a DNA marker has allowed us to follow the expression of Ki67 antigen (Ki67 Ag) as a function of the position of the cells in the cell cycle. The use of drugs blocking the stimulated lymphocytes in different phases of the cell cycle permitted us to demonstrate that Ki67 Ag expression started from the beginning of the first S phase. The level of Ki67 Ag increased during S phase until mitosis, when its expression was maximal. After division, the cells in G1 phase showed a decrease in Ki67 Ag expression (possibly corresponding to degradation) until they reentered S phase, when the level of Ki67 Ag increased again. The results confirm that the expression of Ki67 Ag is related to the proliferative state of the cells and suggest that it may be used to determine the proliferative cell fraction in hematopoietic tissues.

Application of the monoclonal antibody Ki-67 on prostate biopsies to assess the fraction of human prostatic carcinoma

The feasibility of using the monoclonal antibody Ki-67 as a proliferation marker in human prostatic carcinoma was studied on aspiration and core biopsy specimens obtained from 50 patients suspected of having prostate cancer. In 32 prostatic adenocarcinomas the Ki-67 index varied from 0.3 to 13.3% (mean 4.3) in cytological smears and from 0.8 to 17.8% (mean 5.1) in frozen sections from histological core biopsies. No significant correlation between the percentage of cells positive for Ki-67 and the histological tumor differentiation could be established. In 18 patients with benign prostatic hyperplasia the Ki-67 index varied from 0 to 3.0% (mean 1.2) and from 0 to 3.8% (mean 1.4) in cytological and histological material, respectively. The differences in the observed Ki-67 index between benign and malignant prostatic tissues are of statistical (p less than 0.001) and of clinical significance. Nine patients who underwent endocrine treatment or radiotherapy entered a followup protocol in which the Ki-67 staining procedure was applied to periodically obtained cytological aspiration biopsies. During month 1 after the start of therapy a statistically significant (p less than 0.05) decrease in the Ki-67 index to 58% of the initial values was found, while at 2 and 3 months the proliferative fraction showed a further decrease to 27 and 7%, respectively. As a marker, the monoclonal antibody Ki-67 was shown to provide a reliable method to estimate the proliferative cell fraction of human prostate cancer.

Aberrant Ki-67 expression in normal bone marrow revealed by multiparameter flow cytometric analysis

Ki-67 is a commercially available monoclonal antibody that reacts with a nuclear antigen detectable in proliferating cells only. Since its first description, it has been widely used as a "universal" proliferation marker and few groups have questioned the validity of the initially described reactivity, although this was tested only on very restricted experimental models. We wanted to check its reactivity on normal bone marrow (BM) samples using a multiparameter flow cytometric analysis. Although we were able to reproduce the findings of Ki-67 positivity on cultured and stimulated cells, we could not detect any convincing Ki-67 positivity on nuclei of normal BM samples. These samples all had a noticeable proliferating compartment as evidenced by their DNA content. These data are in contrast with the data we obtained starting from stressed marrows and marrows cultured in the presence of hematopoietic growth factors, where we found a marked Ki-67 positivity. This discrepancy suggests that bone marrow cells, growing and proliferating under steady-state conditions and guided by natural control mechanisms, may lose their Ki-67 expression upon exiting the progenitor compartment and entering the differentiating compartment.

Sinus histiocytosis with massive lymphadenopathy: immunological, cytogenetic and molecular studies

We describe a case of "sinus histiocytosis with massive lymphadenopathy" (SHML) studied by immunohistochemical, cytogenetic and molecular analysis. The immunophenotyping showed that the lymph node histiocytes were strongly positive for the S-100 protein and MoAb LeuM3, OKM5, KP1 and DRC-1; a portion of these cells was also positive for OKT6 and Leu3A, suggesting a possible relationship with the veiled cells, which represent an intermediate step in the pathway from the Langerhans cell to the interdigitating reticulum cell. Cytogenetic analysis showed a normal prevalent clone and a small hypodiploid clone and the molecular study showed no detectable involvement of the c-fms proto-oncogene, which is related to monocyte/macrophages. Unfortunately all these data do not seem sufficient to define the benign or neoplastic nature of the disease. Further investigations, immunophenotypical, cytogenetic and molecular, are needed to elucidate the pathogenesis of the disease, especially for more aggressive cases or for cases with unfavorable evolution.

Simultaneous flow cytometric analysis of surface markers and nuclear Ki-67 antigen in leukemia and lymphoma

The monoclonal antibody Ki-67 identifies an antigen present during the late G1, S, G2, and M phases of the cell cycle, whereas resting cells do not express this antigen. Immunostaining with Ki-67 provides a simple method with which to determine the growth fraction of a malignant cell population without requiring a laborious procedure or use of radioactive materials. Thus far, detection of Ki-67-positive cells by flow cytometry was limited because of nuclear location of the antigen. In this study, periodate-lysine-paraformaldehyde (PLP) fixation of cells in suspension, labeling with Ki-67, and the subsequent flow cytometric analysis of the tumor growth fraction is described. Fixation with PLP at -10 degrees C for 15 min rendered the plasma membrane permeable without destroying cell surface antigens. Thus double immunofluorescence studies using both a surface marker and Ki-67 could be performed. This offers the additional advantage of being able to define the phenotype of proliferating cells. This method was applied to determine the growth fraction in peripheral blood and bone marrow samples of patients with leukemia and non-Hodgkin's lymphoma. The results of Ki-67 studies in 91 patients are shown. A wide variability of individual Ki-67 values was observed within each entity. Use of this flow cytometric procedure substantially facilitates the quantification of proliferating cells in pathological blood and bone marrow samples.

Histological and immunohistological analysis of human lymphomas

Morphological and immunological characteristics of lymphoproliferative diseases are reviewed. In particular, a basic distinction is made between non-Hodgkin's lymphomas and Hodgkin's disease. As to the non-Hodgkin's lymphomas, emphasis is given to the problems of classification, technical approach, histogenesis, and prognosis. The authors adopt a version of the Kiel Classification modified to take account of new knowledge regarding T-cell lymphomas. The value of immunophenotyping in making an accurate distinction between the various categories is stressed; immunocytochemical detection of the growth fraction is also discussed and then proposed as a new prognostic tool. Finally, the criteria for differential diagnosis between non-Hodgkin's lymphomas, malignant histiocytosis, non-lymphoid large cell tumors, and atypical immune reactions are outlined.