An apoptosis differentiation programme in human polymorphonuclear leucocytes.

Human PMNs (polymorphonuclear leucocytes or neutrophils) are essential to the innate immune response against bacterial pathogens and are a key part of the acute inflammatory response. Although progress has been made, the molecular basis for termination of inflammation during bacterial infection in humans is largely undefined. To that end, we used genomics strategies to gain new insight into processes that facilitate resolution of neutrophil-mediated inflammation and bacterial infection. On the basis of a series of recent studies, we propose that global changes in PMN gene expression after phagocytosis comprise an apoptosis differentiation programme, which represents the final stage of transcription-regulated PMN maturation. Our studies indicate that the apoptosis differentiation programme regulates multiple post-phagocytic processes in human neutrophils, such as cell fate and proinflammatory activity, and is modulated by PMN-derived reactive oxygen species. Collectively, these studies establish a global model of host cell-pathogen interaction, which provides fundamental insight into the resolution of infection in humans.

The transient appearance of small blastoid cells in the marrow after bone marrow transplantation.

Of 14 patients who underwent allogeneic or syngeneic bone marrow transplantation, 6 had a transient appearance of small blastoid cells in the bone marrow after transplantation. Most of these patients (11) had leukemia, although 3 had severe aplastic anemia. The cells were 8-18 micron in diameter and had scant cytoplasm and dense nuclei with smooth, homogeneous chromatin. They often had distinct nuclear clefts. These cells constituted 4.0-21.3% of the total number of bone marrow cells. They were not reactive with peroxidase, alpha-naphtyl butylate esterase, naphthol AS-D chloroacetate esterase, or periodic acid-Schiff stains. Immunocytochemical analysis revealed that the small blastoid cells expressed terminal deoxynucleotidyl transferase, Ia-like, CD19, and CD10 antigens and cytoplasmic mu heavy chains, indicating a precursor B-cell phenotype. CD20 antigen was not expressed on these cells. The data suggest that cytoplasmic mu may be expressed earlier than CD20 antigen in the differentiation of B-cell lineage. The morphologic, cytochemical, and immunophenotypic characteristics did not distinguish these nonneoplastic cells distinctly from leukemic lymphoblastic cells. The increase of small blastoid cells was a transient and self-limited phenomenon, in contrast to that of neoplastic blasts. These cells should be recognized as a common component of the bone marrow of marrow transplant recipients. The significance and role of these cells in immune recovery and hematopoiesis remain uncertain.