The pattern of cell growth in reticulum cell sarcoma and lymphosarcoma

Prognostic significance of the S-phase fraction of light-chain-restricted cytoplasmic immunoglobulin (cIg) positive plasma cells in patients with newly diagnosed multiple myeloma enrolled on Eastern Cooperative Oncology Group treatment trial E9486

The bone marrow plasma cell labeling index (PCLI) as measured by bromodeoxyuridine uptake is a well-established independent prognostic factor for patients with newly diagnosed multiple myeloma, but the test is not easily done in most laboratories. The purpose of this study was to determine if the proliferative activity (% S-phase) as determined by two-color flow cytometry for cytoplasmic immunoglobulin (cIg) light chain and DNA content also had prognostic significance. As part of Eastern Cooperative Oncology Group clinical trial E9486, 500 patients had successful performance of the bone marrow PCLI. Of 349 patients who had flow cIg and DNA content cytometry, 210 had adequate data to reliably calculate S-phase %. Patients with low % S-phase fraction (<2%) had a significant overall survival advantage over patients high % S-phase fraction (>/=2%), median survivals 4.1 vs. 2.9 years (P = 0.032). Measurement of the S-phase % by flow cytometry gives significant prognostic information in patients with newly diagnosed myeloma. However, in multivariate analysis, S-phase % did not add prognostic information when PCLI was in the model. S-phase % added prognostic information only when all cases with flow measurement of S-phase % were included, and when PCLI was excluded from the model. Discriminating a population of only cIg positive cells proved difficult in patients with a low percentage of bone marrow plasma cells. Methodology to measure S-phase % in patients with a low percent plasma cells is needed before this technique can be used for diagnosis and prognosis in myeloma.

DNA flow cytometry of follicular non-Hodgkin's lymphoma

S-phase fraction, an index of cellular proliferation, and DNA ploidy were measured by DNA flow cytometry in a retrospective study of lymph node biopsy specimens from 83 cases (before treatment) of follicular non-Hodgkin's lymphoma, Working Formulation categories B and C. The correlations between these measures and survival, clinical stage, symptoms and histopathological factors were investigated. Aneuploidy was rare (n = 16) and had no effect on length of survival or transformation to high grade lymphoma. The overall mean S-phase fraction was 3.6%; for the whole series increasing S-phase fraction was associated with decreased survival. A high S-phase fraction (more than 5%) in initial biopsy specimens was also associated with an increased risk of subsequent high grade transformation at relapse. There was no difference between the survival or proliferative activity of tumours composed of mainly small cleaved cells compared with those composed of mixed small and large cells. There was no difference in survival or proliferative activity between tumours showing a pure follicular growth pattern and those with a mixed follicular and diffuse growth pattern. Multifactorial analysis showed that an S-phase fraction of more than 5% and B symptoms were the most important factors determining survival in these follicular non-Hodgkin's lymphomas.

The prognostic value of Ki67 immunostaining in non-Hodgkin's lymphoma

The monoclonal antibody Ki67 recognizes an antigen expressed in all phases of the cell cycle except Go. It has been used in 141 biopsies from 138 patients with non-Hodgkin's lymphoma to identify proliferating cells in histological sections. A Ki67 index (the number of Ki67 positive tumour cells divided by the sum of Ki67 positive and negative tumour cells) has been derived by counting 1000 cells in each case. A correction for the presence of non-tumour cells has been incorporated by counting non-tumour cells in serial sections stained with a panel of other antibodies. A very strong correlation between a low Ki67 index (less than 20 per cent) and low grade histology and a high Ki67 index (greater than 20 per cent) and high grade histology was found (Chi2 = 98.0). Ninety-one patients could be analysed for survival and those with low grade lymphoma (n = 38) who had a relatively high Ki67 index (greater than 5 per cent) had a worse survival than those with an index of less than 5 per cent (p less than 0.05). In contrast, there was a trend for those patients with high grade disease with a very high Ki67 index (greater than 80 per cent) to have a better survival than those with a lower index (less than 80 per cent). The patients with high grade disease who achieved complete remission or good partial remission and had a Ki67 index of less than 80 per cent were more likely to relapse than those with an index of greater than 80 per cent (p less than 0.04). These findings could not be explained by the effect of other prognostic factors such as age, stage, or serum albumin. While the use of Ki67 immunostaining has potential drawbacks, it appears to be a simple and reproducible method of determining a tumour proliferative index which provides relevant clinical data.

What is known about tumour proliferation rates to choose between accelerated fractionation or hyperfractionation?

Repopulation of surviving clonogenic tumour cells during fractionated radiotherapy is one of the crucial factors determining cure probability in radiotherapy. Clinical and experimental data suggest that repopulation rates vary considerably between different tumours but may be similar to the cell production rates in the untreated tumour. For those tumours which repopulate fast, such as squamous cell carcinomas, bladder cancer and colorectal carcinomas, accelerated fractionation may be indicated.

Growth fractions in malignant non-Hodgkin's lymphomas (NHL) as determined in situ with the monoclonal antibody Ki-67

The proportion of proliferating cells in malignant non-Hodgkin's lymphomas (NHL) was determined in situ by immunostaining with the monoclonal antibody Ki-67, which reacts with a nuclear antigen that is present only in proliferating cells. A highly significant correlation could be demonstrated between the proportion of Ki-67 positive cells and the classification into high and low-grade NHL according to the Kiel classification. 93.8 per cent of high-grade and 88.5 per cent of low-grade malignancies were correctly allocated to these groups using the percentage of Ki-67 positive cells as discriminant parameter. On the basis of the medians, the degree of proliferation also paralleled the succession of entities within the Kiel classification. Within most of these different entities, however, the ranges of Ki-67 positive cells varied considerably, indicating that the growth fractions within these groups are rather heterogeneous. Thus it might be useful to determine the growth fraction of each individual case of NHL, because this might be of prognostic value.

Cytophotometric measurements of the DNA in Hodgkin lymphomas and non-Hodgkin lymphomas

In smear preparation of lymph nodes excised from 36 patients with a malignant lymphoma the DNA content was estimated in different tumor cells following Feulgen staining by means of quantitative cytophotometric measurements. The tumors investigated included 11 Hodgkin lymphomas and various types of Non-Hodgkin lymphomas (altogether 25). Whereas the small lymphoid cells found in Hodgkin lymphomas show a diploid DNA content with a wide scattering, in the large mononuclear reticular cells (Hodgkin cells) as well as in Sternberg's giant cells only aneuploid DNA values are seen lying in the hyperdiploid, hypertetraploid and hyperoctoploid regions. DNA stemlines are found in the aneuploid regions, but in some cases they are missing. This indicates that we are dealing with malignant tumor cells. In Non-Hodgkin lymphomas with a low grade of malignancy (centrocytic-centroblastic lymphoma, centrocytic lymphoma, CLL) an aneuploid DNA content is found particularly in the large cells (centroblasts, lymphoblasts) with or without a DNA stemline. These cells must be considered as primary malignant tumor cells. In the immunoblastic lymphoma of high malignancy only aneuploid tumor cells are present showing a particularly intense DNA content in the large immunoblasts, whereas a DNA stemline is usually missing. The range of aneuploid values, the number of polyploid tumor cells and the presence or absence of a DNA stemline are important criterions in determining the degree of malignancy. By means of cytophotometric measurements of the DNA content in the tumor cells of malignant lymphomas it is possible to assertain the degree of malignancy and to establish an objective prognosis.

Pyrimidine and purine activities in non-Hodgkin's lymphoma. Correlation with histological status and survival

The levels of the purine catabolic enzymes, adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP), together with the pyrimidine activities, thymidine phosphorylase (TP) and thymidine kinase isozymes (TK) have been determined for cells obtained from solid lymphoid tissue of 38 patients with non-Hodgkin's lymphoma (NHL) and 14 individuals exhibiting benign reactive lymphoid hyperplasia. Within each NHL histological group subtyped according to the Rappaport classification, and in the reactive hyperplasia group, there was considerable variation in these activities. However, higher levels of TK and TP activities occurred in cells of the histologically unfavourable prognostic NHL groups compared with those of favourable histology or reactive hyperplasia. There was an inverse relationship between survival and elevated TK isozyme 1 and TP levels, which was independent of histological classification and clinical staging. These results indicate that, in addition to morphology, estimations of TK and TP of involved lymphoma cells in NHL is of clinical relevance.

Production of a mouse monoclonal antibody reactive with a human nuclear antigen associated with cell proliferation

The production of a mouse monoclonal antibody, Ki-67, is described. The Ki-67 antibody recognized a nuclear antigen present in proliferating cells, but absent in resting cells. Immunostainings with Ki-67 revealed nuclear reactivity in cells of germinal centres of cortical follicles, cortical thymocytes, neck cells of gastrointestinal mucosa, undifferentiated spermatogonia and cells of a number of human cell lines. The Ki-67 antibody did not react with cells known to be in a resting stage, such as lymphocytes, monocytes, parietal cells and Paneth's cells of gastrointestinal mucosa, hepatocytes, renal cells, mature sperm cells, brain cells, etc. Expression of the antigen recognized by Ki-67 could be induced in peripheral blood lymphocytes after stimulation with phytohaemagglutinin, whereas it disappeared from HL-60 cells stimulated with phorbol esters to differentiate into mature macrophages in a resting stage. These findings suggest that Ki-67 is directed against a nuclear antigen associated with cell proliferation. A first series of immunostainings of tumour biopsies indicated that Ki-67 may be a potent tool for easy and quick evaluation of the proportion of proliferating cells in a tumour.

Clinical relevance of markers of cell proliferation in human lymphoid malignancies: a concise review

The major advances being made in the understanding of the biology of human lymphoid malignancies have shown these to be a heterogenous group of tumours with respect to a variety of biological markers. The cell proliferative rate, an important determinant of tumor aggressiveness and response to therapy, is one of the biological phenomena currently being investigated in the lymphoid malignancies, particularly in the non-Hodgkin's lymphomas. In this paper we describe the techniques used in the analysis of cell proliferation in the lymphoid malignancies, and review the patterns of cell proliferation found in the various types of these tumours and the clinical relevance of these findings. We indicate that differences in cell proliferative rate are an important determinant of the response of non-Hodgkin's lymphomas to current therapeutic modalities and may explain the paradox that a significant number of reputed unfavorable tumors are now curable. Finally, we suggest that inherent differences in the proliferative rate of the neoplastic cell(s) of the so-called favorable histological types of non-Hodgkin's lymphomas may determine histologic progression as well as therapeutic responsiveness.

Percentage of cells in the S phase of the cell cycle in human lymphoma determined by flow cytometry

The percentage of cells with S phase DNA content (S cells) was determined by flow cytometry in cell suspensions obtained from 27 patients with non-Hodgkin's lymphomas. DNA was measured in ethanol-fixed cells stained with propidium iodide after RNase treatment. Cells from 17 samples were also exposed to [3H]-thymidine and labeling indices were determined. An excellent linear correlation was observed between the percentage of S cells calculated by flow cytometry and the labeling index (r = 0.95). To determine the relationship between the percentage of S cells and the clinical behavior of the tumors, the survival of the 27 patients was analyzed. None of the patients was undergoing antineoplastic therapy at the time of the study. The patients were separated into 2 groups according to the percentage of S cells calculated by flow cytometry: those with less than 5% S cells and those with higher than 5% S cells. Clinical follow-up ranged from 5 to 20 months. While 7 of 12 patients with tumors containing more than 5% S cells have died of lymphoma (median survival, 9 months), there has been only one death from lymphoma among 15 patients with tumors containing less than 5% S cells. The difference in survival between these two groups is statistically significant (P = 0.01).

Proliferation kinetics of malignant non-Hodgkin's lymphomas related to histopathology of lymph node biopsies

Since lymphomas of high and low malignancy have been differentiated by the Kiel-classification, the cell kinetics of malignant lymphomas have become an interesting subject. In 20 non-Hodgkin's lymphomas we have determined the initial labelling index, the mitosis index, the proliferation rate and the durations of DNA-synthesis and mitosis. The kinetic variables have been estimated by using an in vitro-incubation of fresh biopsies and double-labelling with radioactive DNA-precursors. in 8 lymphomas of low malignancy we found an initial labelling index of 7.8%, a mitosis index of 0.3% and a potential tumour doubling time of 100.2 h for a cell production rate without regard to cell loss. On the other hand, lymphomas of high malignancy showed a labelling index of 16.7%, a mitosis index of 0.7% and a potential tumour doubling time of 40.5 h. All these values could be differentiated with high statistical confidence. DNA-synthesis time and mitosis time of both lymphoma groups did not show any significant differences. From these findings we obtained confirmation of the cyto-morphological principles used in classifying lymphomas.

Tritiated thymidine labeling index of benign and malignant human breast epithelium

38 specimens of benign breast tissue from young women and 92 primary breast carcinomas were evaluated for tritiated thymidine ([3H]TdR) labeling index (TLI) by in vitro pulse labeling. The TLI on nonneoplastic, terminal breast ducts was significantly higher during the latter half than during the first half of the menstrual cycle (P less than 0.001), and a geometric mean TLI of 1.5 during the latter half of the cycle is consistent with approximately 47% turnover of these cells during the menstrual cycle. Ducts of fibroadenomas showed similar menstrual variation TLI. The range of TLI observed in the carcinomas was 0.04-18.6, arithmetic mean 3.7, geometric mean 2.1. The TLI of carcinomas was not significantly correlated with size of the tumor, but tended to be higher in women less than 50 yr old than in women older than 50 yr (P less than 0.05), and in the presence of two or more metastatic axillary lymph nodes than when fewer than two nodes were involved (P less than 0.02).