Increased cell apoptosis in bone marrow trephine biopsies and immunomagnetically isolated myeloid progenitor cells in patients with chronic idiopathic neutropenia.

The frequency of apoptotic cells in bone marrow trephine biopsies and cytospins of immunomagnetically isolated myeloid progenitor cells was determined in 39 patients with chronic idiopathic neutropenia (CIN) and 12 hematologically normal individuals using the in situ end-labeling (ISEL) apoptosis detection method. We found that 66.7% of the patients but none of the normal controls displayed apoptotic cells equal to or higher than 5% of the total mononuclear cells in bone marrow biopsies (p<0.01). In the double stain, we also found that the proportion of apoptotic CD15(+) myeloid precursor cells did not differ significantly between patients and control subjects, while the proportion of apoptotic CD34(+) hemopoietic cells could not be estimated with accuracy because of the presence of CD34(+) endothelial cells. Significantly increased apoptosis was noted in cytospins of immunomagnetically isolated patient CD34(+) and CD34(+)/CD33(+) cells but not CD34(-)/CD33(+) cells, compared to the controls ( p<0.001, p<0.02 and p>0.05, respectively). These findings confirm and extend our previous observations in flow-cytometric studies of apoptosis in CIN, indicating that increased apoptosis in CIN bone marrow concerns mainly the CD34(+) and CD34(+)/CD33(+) progenitor cell compartments. We conclude that the accelerated apoptosis in these compartments may account for the impaired neutrophil production in CIN patients.

Morphologically defined myeloid cell compartments, lymphocyte subpopulations, and histological findings of bone marrow in patients with nonimmune chronic idiopathic neutropenia of adults.

This report describes the morphologically defined myeloid cell compartments, lymphocyte subpopulations, and histological findings of bone marrow in 38 patients with nonimmune chronic idiopathic neutropenia of adults (NI-CINA) and in 14 controls. We found that patients had a striking shift to the left of the granulocytic series due to both an increased proportion of proliferating cells and a reduced proportion of maturating cells compared with controls (P<0.001 and P<0.001, respectively). Individual proportions of these cells strongly correlated with the number of circulating neutrophils (r = -0.462, P < 0.01 and r = 0.495, P<0.01, respectively). However, in the great majority of patients (78.9%), no significant changes in marrow cellularity or the myeloid to erythroid cell ratio could be demonstrated. Patients also had increased proportions of CD19+B cells, CD20+B cells, and plasma cells with polytypic expression relative to controls (P < 0.02, P< 0.01, and P< 0.001, respectively). Individual values of plasma cells were inversely correlated with the number of blood neutrophils (r=-0.414, P<0.01). Dispersed bcl-2+lymphocytic aggregates without germinal centers were seen in about one-third of the patients. T cells and natural killer (NK) cells did not show any significant change. Patients had increased proportions of CD57+, CD16+, and HLA-DR+ cells and, in a few cases, increased proportions of histiocytes and eosinophils. CD45RO+ cells were reduced only in patients with pronounced neutropenia. Expression of p53 protein has not been detected in any cell population. With the exception of some megaloblastoid features of erythroid lineage seen in two patients and the presence of some micromegacaryocytes seen in two others, no significant morphological abnormalities were noted. All of these findings are consistent with our previously reported suggestion for the possible existence of an underlying low-grade chronic inflammatory process in NI-CINA patients, which may be involved in the pathogenesis of neutropenia in the affected subjects.