Search

A higher percentage of apoptotic cells (apoptotic index or AI) is consistently found in bone marrow (BM) biopsies compared to BM aspirates of patients with myelodysplastic syndrome (MDS). Most studies have only investigated the low-density fraction (LDF) mononuclear cells from BM aspirates following density separation for AI determination. In the present study, both LDF and high-density fraction (HDF) cells for AI were examined by electron microscopy (EM) in 10 MDS patients and 4 healthy donors. Matched BM biopsies were subjected to AI detection by in situ end labeling (ISEL) of fragmented DNA. The results indicate that in LDF and HDF cells, AI is consistently higher in MDS patients (8.5% vs 1.5%, respectively; P = .039) compared to healthy donors (27% vs 4%, respectively; P = .004). The BM biopsy AI was also higher in MDS patients than in healthy donors (3+ vs 0+, respectively; P = .036). In addition, in MDS patients, more apoptotic cells were found in HDF cells than in LDF cells (27% vs 8.5%, respectively;P = .0001). All stages of maturation, ranging from blasts to terminally mature cells belonging to all 3 lineages, were represented in the dying cells in both compartments. Using EM, typical Pelger-Huett–type cells appeared to be apoptotic granulocytes. Both LDF and HDF cells should be examined for an accurate estimation of apoptotic cells because AI would be underestimated if only the LDF cells were studied. Ultrastructural studies consistently show a higher AI in BM biopsies compared to BM aspirates despite the correction factor of HDF cells provided by AI. This may represent the actual extant state, which could conceivably be due to a higher concentration of proapoptotic signals in the biopsies.

Our previous studies using in situ end labeling (ISEL) of fragmented DNA revealed extensive apoptotic cell death in the bone marrows (BM) of patients with myelodysplastic syndromes (MDS) involving both stromal and hematopoietic cells. In the present report we show greater synthesis of interleukin-1 beta (IL-1 beta) in 4 hour cultures of density separated BM aspirate mononuclear (BMAM) cells from MDS patients as compared to the cultures of normal BM from healthy donors or lymphoma patients (1.7 +/- 0.37 pg/10(5) cells, n = 29 v 0.42 +/- 0.24 pg/10(5) cells, n = 11, respectively, P = .049). Further, these amounts of IL-1 beta in MDS showed a significant correlation with the extent of apoptosis detected by ISEL in corresponding plastic embedded BM biopsies (r = .480, n = 30, P = .007). In contrast normal BMs did not show any correlation between the two (r = .091, n = 12, P = .779). No significant correlation was found between the amounts of IL-1 beta and % S-phase cells (labeling index; LI%) in MDS determined in BM biopsies using immunohistochemistry following in vivo infusions of iodo- and/or bromodeoxyuridine. Neither anti-IL-1 beta antibody nor IL-1 receptor antagonist blocked the apoptotic death of BMAM cells in 4 hour cultures (n = 5) determined by ISEL (apoptotic index; AI%), although the latter led to a dose-dependent accumulation of active IL-1 beta in the culture supernatants. On the other hand, a specific tetrapetide-aldehyde inhibitor of ICE significantly retarded the apoptotic death of BMAM cells at 1 mumol/L in 5/6 MDS cases studied (AI% = 2.99 +/- 0.30 in controls v 1.58 +/- 0.40 with ICE-inhibitor, P = .05) and also reduced the levels of active IL-1 beta synthesized (5.59 +/- 2.63 v 2.24 +/- 0.93 pg/10(6) cells, respectively). In normal cells, neither IL-1 blockers nor the ICE inhibitor showed any effect on the marginal increase in apoptosis observed in 4 hour cultures. Our data thus suggest a possible involvement of an ICE-like protease in the intramedullary apoptotic cell death in the BMs of MDS patients.

Cell-cycle kinetics were measured in situ after infusions of iododeoxyuridine and/or bormodeoxyuridine in 50 patients with myelodysplastic syndromes (MDS) and the median labeling index in bone marrow (BM) biopsy samples was 28.6%. Unfortunately, 26 of 50 patients showed that > or = 75% of hematopoietic cells of all three lineages were undergoing programmed cell death (PCD) in their biopsy samples as shown by the in situ end labeling (ISEL) technique. Ten patients had 1/3 and eight had 2/3 ISEL+ cells. Stromal cells were frequently ISEL+ and often S-phase cells were also found to be simultaneously ISEL+. Nucleosomal DNA fragments as a ladder in agarose gel were present in BM aspirates of four patients who showed high ISEL and were absent in two who had no ISEL staining in biopsy samples, but only when DNA was extracted after a 4-hour in vitro incubation in complete medium. Therefore, laddering data confirmed the ISEL findings that the majority of hematopoietic cells in MDS are in early stages of PCD. We conclude that extensive intramedullary cell death may explain the paradox of pancytopenia despite hypercellular marrows in MDS patients. Investigating approaches that protect against PCD in some MDS subsets would be of interest.

Huet first observed an abnormal hyposegmented neutrophil granulocyte in 1928, and a year later Pelger reported an additional case. Such a cell later became known as Pelger-Huet anomaly. In 1932 Huet pointed out its hereditary and systemic character.[1][1] The Pelger-Huet anomaly is a familial