Heterochromatin condensation in central and peripheral nuclear regions of maturing lymphocytes in the peripheral blood of patients suffering from B chronic lymphocytic leukemia – a cytochemical study

Abstract

The present study was undertaken to provide complementary information on heterochromatin condensation in central and peripheral nuclear regions during maturation of human leukemic lymphocytes using simple image processing and DNA image densitometry at the single cell level. Such approach indicated that the heterochromatin condensation in perinucleolar and extranucleolar "gene rich" central nucleolar regions preceded that in the "gene poor" nuclear periphery at the nuclear membrane. Thus, the maturation of lymphocytes was accompanied by a marked increase of the heterochromatin condensation at the nuclear membrane that reflected the maturity of these cells. In addition, in contrary to the nuclear size, no substantial differences of the heterochromatin condensation in central and peripheral nuclear regions were noted between untreated and treated patients with cytostatic therapy at the time of taking samples for the present study. On the other hand, the larger heterochromatin condensation in central nuclear regions occasionally persisted in small mature lymphocytes of all studied patients. Such phenomenon might represent the return to the cell cycle or a further type of maturation asynchrony that in leukemic cells is not exceptional. Keywords: heterochromatin, central and peripheral nuclear regions, maturing human leukemic lymphocytesIt is generally known that the maturation of blood cells is characterized by an increasing chromatin condensation and a decreasing nuclear size [1]. Moreover, according to numerous studies it seems to be apparent that condensed chromatin -heterochromatin -is a morphological manifestation of genetic silencing and terminal differentiation [2 ,3 ,4]. However, the information on the heterochromatin condensation state in central and peripheral nuclear regions in maturing cells is very limited or missing [5 6]. It should be mentioned that central nuclear regions possess gene rich chromosomal territories and gene poor chromosomal territories are in the nuclear periphery at the nuclear membrane [2,7,8,9]. The present study was undertaken to provide complementary information on the heterochromatin in various nuclear regions of human leukemic lymphocytes during their maturation. These cells represent a very convenient model for such study because they are present in a satisfactory number in the peripheral blood of patients suffering from B-cell chronic lymphocytic leukemia. In addition, the morphology of lymphocytes is well known and immature proliferating and mature resting or terminal stages of these cells are easily identified [1,10,11]. The chromatin structure was visualized using a simple cytochemical procedure for DNA and the state of the heterochromatin condensation was determined by computer assisted image densitometry in situ at the single cell level.The results clearly indicated that the maturation of lymphocytes was accompanied by a marked increase of the heterochromatin density -condensation -in nuclear peripheral regions at the nuclear membrane. Thus, the increased heterochromatin c...

The Heterochromatin Condensation State in Peripheral “Gene Poor” and Central “Gene Rich” Nuclear Regions of Less Differentiated and Mature Human Leukemic Cells: A Mini-Review with Additional Original Observations

“…From the methodical point of view, the heterochromatin condensation state in single cell nucleus may be easily visualized in situ by a simple image processing or by the computer assisted optical image densitometry [5,6]. Such approaches facilitate to see clearly how the heterochromatin condensation state in central and peripheral nuclear regions differs between proliferating and not-proliferating cells and develops in differentiating or maturing cells (Figure 1).…”

“…It is possible to measure the heterochromatin density in digital images of stained cells by the polychrome procedure after the conversion of captured color images to gray scale using the red channel (NIH Image Program, Scion for Windows, Scion Corp., USA). The polychrome May-Grünwald -Giemsa-Romanowsky staining procedure is useful not only for the cell identification including differentiation and maturation stages but also for .the heterochromatin density measurements [1,[4][5][6]20]. The calculated arbitrary density units facilitate to estimate the ratio of the mean heterochromatin condensation state in central to peripheral nuclear regions (Figure 1).…”

“…The calculated arbitrary density units facilitate to estimate the ratio of the mean heterochromatin condensation state in central to peripheral nuclear regions (Figure 1). Such ratio appeared to be very useful for comparative studies of various cell lineages including their differentiation and maturation stages [5,6].…”

“…condensation state in individual cells using arbitrary density units [5,6] (Figure 1). It is possible to measure the heterochromatin density in digital images of stained cells by the polychrome procedure after the conversion of captured color images to gray scale using the red channel (NIH Image Program, Scion for Windows, Scion Corp., USA).…”

“…On the other hand, the heterochromatin condensation state was less studied although it appeared to be different in both "gene rich" and "gene poor" nuclear regions [5,6]. Numerous studies also demonstrated that the heterochromatin reflects the presence of silent genes [7][8][9][10][11].…”