Cytochemical characterization of mouse L1210 leukemia

Cell-death assessment by fluorescent and nonfluorescent cytosolic and nuclear staining techniques

Apoptosis, a genetically programmed cellular event leads to biochemical and morphological changes in cells. Alterations in DNA caused by several factors affect nucleus and ultimately the entire cell leading to compromised function of the organ and organism. DNA, a master regulator of the cellular events, is an important biomolecule with regards to cell growth, cell death, cell migration and cell differentiation. It is therefore imperative to develop the staining techniques that may lead to visualize the changes in nucleus where DNA is housed, to comprehend the cellular pathophysiology. Over the years a number of nuclear staining techniques such as propidium iodide, Hoechst-33342, 4', 6-diamidino-2-phenylindole (DAPI), Acridine orange-Ethidium bromide staining, among others have been developed to assess the changes in DNA. Some nonnuclear staining techniques such as Annexin-V staining, which although does not stain DNA, but helps to identify the events that result from DNA alteration and leads to initiation of apoptotic cell death. In this review, we have briefly discussed some of the most commonly used fluorescent and nonfluorescent staining techniques that identify apoptotic changes in cell, DNA and the nucleus. These techniques help in differentiating several cellular and nuclear phenotypes that result from DNA damage and have been identified as specific to necrosis or early and late apoptosis as well as scores of other nuclear deformities occurring inside the cells.

Lectins detect changes of the glycosylation status of plasma membrane constituents during late apoptosis

BACKGROUND

Mechanisms governing the normal resolution processes of inflammation are poorly understood, yet their elucidation may lead to a greater understanding of the pathogenesis of chronic inflammation. The removal of apoptotic cell material and their potentially histotoxic contents is a prerequisite of resolution. Engulfment by macrophages is an important disposal route, and changes in the apoptotic cells that are associated with their recognition by macrophages are the subject of this report.

METHODS

Apoptosis and necrosis in primary cells and cell lines were induced by various stimuli. The binding profile of 23 different lectins for vital, apoptotic, and necrotic cells were analyzed by flow cytometry.

RESULTS

We observed that lectins were able to attach to the cell surfaces of vital and dying cells. Some lectins exhibited membrane destructive properties and, consecutively, changed the morphology of the cells as detected by flow cytometry. Other lectins did not show differences in their binding to viable and apoptotic cells. Those lectins were, therefore, not used for analyses of surface changes. The lectins Griffonia simplificolia II (GSL II), Narcissus pseudonarcissus (NPn), and Ulex europaeus I (UEA I) showed no cytotoxic activity and bound preferentially to dying cells. Primary and secondary necrotic cells displayed an equal staining intensity, which was substantially higher than for apoptotic cells. The binding of GSL II, NPn, and UEA to dying cells increased in a time-dependent manner and was delayed to AxV positivity and the decrease in the mitochondrial membrane potential of apoptotic cells. The kinetic of the lectin staining correlated with the increase in subG1-DNA. GSL II, NPn, and UEA are specific for N-acetylglucosamine, mannose, and fucose, respectively.

CONCLUSION

According to their binding specificity, we conclude that N-acetylglucosamine-, mannose-, and fucose-containing epitopes are increasingly exposed on cells undergoing apoptosis.

Lectinocytochemical detection of apoptotic murine leukemia L1210 cells

BACKGROUND

Various cytomorphologic and biochemical markers of apoptosis are found in different compartments (plasma membrane, cytoplasm, nucleus, and mitochondria) of target cells. Although the plasma membrane is an easily accessible cellular compartment, relatively little is known about its changes during apoptosis. We investigated whether specific changes in the expression of plasma membrane glycoproteins take place during apoptosis and whether these changes could be used for a quantitative estimation of apoptosis.

METHODS

Lectin cytochemical study of normal and apoptotic murine leukemia cells of the L1210 line was done. Horseradish peroxidase-labeled Laburnum anagyroides bark agglutinin, Phaseolus vulgaris agglutinin, Pisum sativum lectin (PSL), Ricinus communis agglutinin (RCA-120; 120 kDa), Solanum tuberosum agglutinin, Triticum vulgaris lectin (wheat germ agglutinin), Viscum album agglutinin, Canavalia ensiformis lectin (concanavalin A), and Helix pomatia lectin were used to compare specific glycoprotein expressions in normal and apoptotic murine leukemia cells of the L1210 line sensitive (L1210) and resistant (L1210R) to apoptosis induction by cisplatin.

RESULTS

The data demonstrated significantly increased binding of alpha-D-mannose-specific PSL lectin (P<0.01) and beta-D-galactose-specific RCA-120 lectin (P<0.001) by the apoptotic cells of the L1210 and L1210R lines in comparison with the intact cells. That binding was shown to be specific because it was blocked by the corresponding inhibitory sugars.

CONCLUSIONS

Lectins specific to alpha-D-mannose (PSL) and beta-D-galactose (RCA-120) can be used to distinguish between native and apoptotic murine leukemia L1210 cells and to quantitatively estimate apoptosis in a population of these cells.

Populations of thymocytes and peripheral blood leucocytes in leukaemia-bearing mice treated with G-CSF

The influence of granulocyle-colony stimulating factor (G-CSF) on thymocyte subsets and peripheral blood leucocytes in leukaemia L1210-bearing mice was evaluated. Leukaemia-bearing mice have a markedly reduced L3T4+Lyt2+ thymocyte subpopulation. We observed "correction" of relative values of thymocyte subpopulations induced by treatment of mice with a G-CSF preparation. The suggestion is presented that this could result from liberation of lymphocyte T precursor cells from the bone marrow and increased homing of them into the thymus. The direct or indirect influence of G-CSF on the L3T4+Lyt2+ subpopulation of thymocytes is discussed.

Successful adoptive immunotherapy of minimal residual disease after chemoradiotherapy and transplantation of bone marrow purged of leukaemia with mafosfamide

The effectiveness of adoptive immunotherapy in eliminating minimal residual disease in tumour-bearing mice after bone marrow transplantation was tested. This model mimics the human clinical condition when autologous bone marrow was purged ex vivo of leukaemia with mafosfamide or was not purged, and stored in liquid nitrogen before transplantation. Animals with minimal residual disease were prepared with marrow-ablative but leukaemia-noncurative doses of cyclophosphamide (CY) and total body irradiation followed by bone marrow transplantation. The next day after transplantation the recipients were injected with splenocytes immunized against the leukaemia cells (Imm-SPL) or monoclonal antibody (mAb). All the control mice died from leukaemia relapse, but 51% of purged bone marrow recipients, which received Imm-SPL, were cured. In similar conditions mAb did not exert a therapeutic effect. Imm-SPL were not able to eradicate minimal residual disease in the recipients of nonpurged bone marrow. Thus, in an animal model, we demonstrated that purging of bone marrow before grafting seems to be indispensable for successful adoptive immunotherapy of minimal residual disease (MRD) after autologous bone marrow transplantation.