Prognostic significance of the labeling index in non-Hodgkin human malignant lymphomas

Optimal conditions for immunohistochemical determination of the in vitro DNA synthesis labelling index with bromodeoxyuridine in head and neck cancer

The in vitro DNA synthesis labelling index was assessed immunohistochemically in 24 freshly obtained specimens of head and neck cancer using bromodeoxyuridine (BrdUrd) as the DNA precursor to determine the influence of BrdUrd concentration on labelling index (LI). Initially, tumour fragments were incubated in varying concentrations of BrdUrd from 2 to 100 microM for 2 h, and BrdUrd was detected with an anti-BrdUrd monoclonal antibody using immunoperoxidase labelling. There was a dose-response gradient with mean LI varying from 1.6% at 2 microM BrdUrd to 8.8% at 100 microM. The concentration-response gradient best fit a quadratic model when LI was plotted against log BrdUrd concentration (r = 0.65, P less than 0.0001). Eleven additional tumours were then studied to determine whether LI increased for BrdUrd concentrations above 100 microM. The mean LI at 125 microM and at 150 microM in these 11 tumours did not differ from the value at 100 microM, suggesting a plateau at this level. The gradient effect accounted for 17% of the variance in LI, while 60% of the variance was explained by between tumour differences. Within individual tumours, three response patterns were observed: (i) LI rose at a constant rate to the highest concentration tested (n = 8), (ii) the LI plateaued or declined at high BrdUrd concentrations (n = 6); and (iii) there was a biphasic slope slope in which the rate of rise in the LI increased at the higher BrdUrd concentrations (n = 2). The data show that BrdUrd concentration is an important variable in the immunohistochemical assessment of the in vitro LI in head and neck cancer.

Determination of proliferative fractions detected by immunohistochemistry with the monoclonal antibodies to bromodeoxyuridine and Ki-67 in malignant lymphomas

The stainability of proliferating cells with monoclonal antibodies to both bromodeoxyuridine (BrdU) and Ki-67 were compared in 22 malignant lymphomas and six related conditions. A significant correlation was observed (r = 0.78) between the positivities of proliferating cells determined using these two monoclonal antibodies. The growth fractions determined with the antibodies were usually related to the histologic classification, but labelling index was more varied in diffuse large cell type lymphoma. BrdU labelling was well correlated with the Working Formulation, and more useful as a prognostic indicator. On the other hand, Ki-67 was useful for broad recognition of cell proliferative ability.

Validation of a mathematical procedure for computer analysis of flow cytometric DNA data in human tumors

The determination of tritiated thymidine labeling index and the percentage of cells with S phase DNA content was performed on cell suspensions obtained from 69 patients with non-Hodgkin's lymphoma. The distributions of cells in the cell cycle by computer analysis of flow cytometric data were obtained by two mathematical procedures: the widely adopted Fried model and a new one proposed by Bruni et al. A significant agreement was observed by checking the Spearman index (rs) between the percentages of cells in the different cell cycle phases (G0/1, rs = 0.76; S, rs = 0.60; and G2 + M, rs = 0.43; p less than 0.001) determined by the two procedures. Similarly, a good correlation was observed between the labeling index (LI) and the S phase values obtained by the Fried (rs = 0.45, p less than 0.001) and Bruni (rs = 0.69, p less than 0.001) models, but with a higher agreement for the latter one. The S phase by the Bruni model was also superior in predicting LI: in fact, by employing the S cutoff value of 12%, a better agreement between low LI and low S phase or high LI and high S phase was observed with the Bruni procedure (90%) than with the Fried model (72%). Finally, the analysis of the prognostic significance of the different kinetic variables confirmed the prognostic relevance of LI at any time; the S phase percentage as determined by Bruni et al. was discriminant of survival only at shorter times, and no prognostic significance could be ascribed to S phase according to the Fried procedure.

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.

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.