Karly A. Jacobsen

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Studies of cell population dynamics and microenvironmental organization of B lymphopoiesis in the bone marrow of normal mice and in various genetically modified states have shown that cell loss, involving processes of apoptosis and macrophage-mediated cell deletion, is a prominent feature of the primary genesis of B lymphocytes. Balanced against the(More)
Cell adhesion molecules (CAMs) play a key role in interactions between stromal and hematopoietic cells in bone marrow (BM) and in cell traffic through vascular endothelium. To examine the identity of CAMs involved in these processes in mouse BM, we have investigated the in vivo expression of vascular cell adhesion molecule-1 (VCAM-1) and its(More)
B lymphocyte precursor cells expressing B220 glycoprotein have been examined in mouse bone marrow (BM) by the in vivo binding of monoclonal antibody (mAb) 14.8 visualized by light and electron microscope radio autography. Young mice were injected intravenously with 125I-labeled mAb 14.8 and then perfused to remove unbound antibody. Quantitative analysis of(More)
The vast majority of lymphocytes generated daily in the chicken bursa of Fabricius do not emigrate to the periphery but die in situ. Apoptotic cells in the bursa can be readily detected by the presence of fragmented DNA and by the large numbers of condensed cellular nuclei observed by electron microscopy. Consequently, most newly generated lymphocytes die(More)
Mice homozygous for the scid (severe combined immunodeficiency) mutation are generally unable to produce B lymphocytes, a condition attributed to defective rearrangement of immunoglobulin genes in precursor B cells. Some early B-lineage cells are present in the bone marrow (BM), however. In scid mice, we defined three subsets of early progenitor B cells(More)
Transgenic mice expressing the c-myc proto-oncogene under the control of the Ig heavy chain enhancer (E mu-myc) all eventually develop clonal pre-B- or B-cell tumors. The preneoplastic period is characterized by increased polyclonal proliferation of pro-B and pre-B cells in the bone marrow (BM) associated with a reduced number of B cells, suggesting a high(More)
The localization of early B-lymphocyte precursor cells in the bone marrow of young mice has been studied during recovery from sublethal whole body gamma-irradiation (150 rad). Initial studies by double immunofluorescence labeling of the B-lineage-associated cell surface glycoprotein, B220, and of mu heavy chains in bone marrow cell suspensions, demonstrated(More)
Immunoglobulin gene rearrangement in the chicken has evolved not to generate antibody diversity per se but to generate an immunoglobulin variable region which can be diversified by subsequent somatic gene conversion events. While the molecular mechanism of V(D)J recombination in chickens cannot be distinguished from that seen in other species, the way in(More)
B lymphocyte precursor cells in mouse bone marrow develop in close association with stromal cells which provide essential growth signals. To identify molecules that may normally play a role in this interaction we have examined the in vivo binding of a new monoclonal antibody (mAb) (KMI6) that recognizes a determinant on a bone marrow stromal cell line(More)