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T W LeBien

Publications and source records attributed to T W LeBien.

14 recordsLinked to original sources
PubMed1991

Development of a bone marrow culture for maintenance and growth of normal human B cell precursors.

The absence of long term bone marrow cultures for studying the growth and differentiation of human B cell precursors (BCP) has placed restrictions on the ability to analyze the early stages of human B cell ontogeny. We now describe a bone marrow-derived adherent cell microenvironment that maintains human BCP for several weeks in vitro. The adherent cells are maintained in a serum-free tissue culture medium, and consist of a predominant population of CD10+ fibroblast-like cells and a minor population of CD10+/nonspecific esterase+ macrophages. Adherent cell cultures seeded with fresh or cryopreserved fetal bone marrow, or purified CD10+/surface IgM- cells, provide a supportive microenvironment for lymphoid cells with a predominant phenotype of CD10+/CD19+/HLA-DR+/surface IgM-. Supplementation of the adherent cell cultures with human IL-7 induces active growth of BCP during the first 14 to 21 days of culture. However, the expansion of these cells does not continue past 21 days, and the cultures undergo a steady decline in BCP. Analysis of adherent cell conditioned medium revealed the presence of an unidentified soluble factor (or factors) that acts in concert with IL-7 to promote the growth of CD10+/surface IgM- cells. This culture system will be useful in elucidating the patterns of gene expression and growth factor requirements that characterize normal human B cell ontogeny, and perturbations of normal B cell ontogeny that lead to immunodeficiency and leukemia.

Antigens, CD↗
PubMed1991

Expression of interleukin-4 receptors on early human B-lineage cells.

Interleukin-4 (IL-4) regulates multiple stages of the antigen-dependent phase of B-cell development. However, its precise role in regulating B lymphopoiesis in bone marrow is not as well defined. We examined whether surface IgM- normal and leukemic human B-cell precursors (BCP) expressed IL-4 receptors using biotinylated IL-4. Constitutive expression of IL-4 receptors was detected on both normal and leukemic BCP. A higher percentage of normal BCP (82% +/- 15%) expressed IL-4 receptors compared with leukemic BCP (44% +/- 8%). Using mean fluorescent intensity as an indicator of receptor level on the IL-4 receptor positive cells, normal (91 +/- 41) and leukemic (44 +/- 37) BCP expressed comparable numbers of receptors. IL-4 induced the expression of CD23 on 30% of the leukemic BCP cases examined. IL-4 induced CD23 on surface IgM+ fetal bone marrow lymphoid cells but not on the surface IgM- normal BCP, despite the presence of detectable receptors on the surface IgM- cells. IL-4 did not stimulate proliferation of normal BCP, nor could it enhance the effect of recombinant IL-7 or low molecular weight B-cell growth factor. However, IL-4 increased the expression of surface IgM and surface Ig kappa on in vitro differentiated pre-B cells. Our collective results identify no role for IL-4 in the proliferation of normal or leukemic BCP, but identify a role in the enhancement of surface Ig expression during pre-B to B-cell differentiation.

B-Lymphocytes↗
PubMed1991

Biochemical and histochemical characterization of a murine tubular antigen.

Cellular components of the developing fetal nephron express certain cell surface antigens at discrete stages of nephron development. To further evaluate the expression of antigens by tubular epithelium, a rat monoclonal antibody (BL26) was developed against murine fetal kidney. BL26 identified a differentiation antigen expressed by epithelial cells of the ureteric bud and late S-body in developing nephrons and by endothelium, mesangium, and distal tubular epithelium in mature nephrons. The polypeptide identified by BL26 was shown to be synthesized by fetal kidney and renal adenocarcinoma cells. The polypeptide contained no detectable carbohydrate modifications but was found in two isoforms, an acylated (26,000-Da) form and a nonacylated (24,000-Da) form. The murine antigen recognized by BL26 and the human CD9 moiety, an acylated polypeptide with a tissue distribution similar to that of the BL26 antigen, comigrated in polyacrylamide gels. We speculate that expression of the BL26 antigen and CD9 reflects processes relating to the activation of epithelial cells.

Animals↗
PubMed1991

Autologous bone marrow transplantation for progressive non-Hodgkin's lymphoma: clinical impact of immunophenotype and in vitro purging.

From 1983 to 1989 we performed a prospective trial of 70 consecutive, in vitro purged autologous bone marrow transplants (BMT) for patients with progressive non-Hodgkin's lymphoma. Forty-nine patients had responsive disease at the time of transplantation while 21 others had refractory high risk lymphoma. Forty-two patients with B-lineage lymphoma received autologous marrow purged in vitro with monoclonal antibody (anti CD9, CD10, CD24) plus complement, 12 with T-lineage lymphoma received monoclonal antibody immunotoxins (anti CD5, CD7-ricin conjugates) along with 4-hydroperoxycyclophosphamide purging and 16 received unpurged marrow. All received cyclophosphamide, 57 with fractionated total body irradiation, and 13 with BCNU and cytarabine. Hematologic engraftment was prompt and unaffected by phenotype (B vs. T) or by in vitro purging used (B vs. T vs. none) although nine of 16 non-relapse deaths were related to poor graft function. Fifty-one patients (73%) were alive in complete remission (CR) 1 month following transplantation while 15 patients (12 with initially refractory disease) had persistent disease. Subsequently, 41 +/- 18% (by Kaplan-Meier estimate; +/- 95% confidence limits) of those who achieved CR remained relapse free 1-6.4 (median 3) years post-BMT. Neither risk group, purging, nor immunophenotype predicted subsequent post-transplant relapse. Among those 51 who achieved CR, 13 of 43 (27 +/- 14%) with responsive disease survive disease free while three of eight (38 +/- 34%) refractory patients survive disease free (p = 0.96). Overall, 24 patients survive, 16 in continuous complete remission 1-6.5 years following transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Analysis of immunoglobulin and T-cell receptor gene rearrangements in human fetal bone marrow B lineage cells.

Fetal bone marrow B lineage cells representing multiple stages of B cell development were isolated by two-color cell sorting and analyzed for immunoglobulin H and T-cell receptor (TCR) gamma and delta gene rearrangements. Analysis of CD10+/surface mu- cells using a JH probe revealed a high frequency of rearrangements; some of these rearrangements used the 3' D region gene DQ52. Analysis of CD10+/surface mu- cells revealed no detectable TCR-gamma or -delta rearrangements, nor were TCR-delta rearrangements detected in CD10+/surface mu+ cells, despite the limited repertoire of these genes. These observations are surprising given the high frequency of TCR delta/gamma rearrangements in B cell precursor acute lymphoblastic leukemia, and identify a potential difference in patterns of gene rearrangement that distinguish normal and leukemic B cell precursors.

B-Lymphocytes↗
PubMed1990

Differentiation of normal human pre-B cells in vitro.

The differentiation of surface Ig- pre-B cells into surface Ig+ B cells is a critical transition in mammalian B cell ontogeny. Elucidation of the growth factor requirements and differentiative potential of human pre-B cells has been hampered by the absence of a reproducible culture system that supports differentiation. Fluorescence-activated cell sorting and magnetic bead depletion were used to purify fetal bone marrow CD10+/surface mu- cells, which contain 60-70% cytoplasmic mu+ pre-B cells. CD10+/surface mu- cells cultured for 2 d were observed to differentiate into surface mu+ cells. Analysis by Southern blotting provided direct evidence that rearrangement of kappa light chain genes occurs in culture, and flow cytometric analysis revealed the appearance of surface Ig+ B cells expressing mu/kappa or mu/lambda. Unexpectedly, the kappa/lambda ratio in differentiated cells was the inverse of what is normally observed in adult peripheral blood. Differentiation occurs in the absence of exogenous growth factors or cytokines, suggesting that a stimulus-independent differentiative inertia might characterize pre-B cells in vivo. Future use of this model will facilitate our understanding of normal and abnormal human pre-B cell differentiation.

Antigens, Differentiation↗
PubMed1990

Multiparameter flow cytometric analysis of human fetal bone marrow B cells.

Maturation of adult human bone marrow (BM) B cells is accompanied by the sequential acquisition and loss of characteristic cell surface antigens (Loken et al., Blood 70:1316). Little is known about these changes in fetal BM B cells. In order to compare fetal with adult B cell development, we performed three-color, flow cytometric analyses of cell surface antigens, as well as nuclear TdT staining, on lymphoid cells from fetal BM. Mononuclear cells isolated from fetal BM (18-22 weeks) were stained with combinations of antibodies against CD3, CD10, CD19, CD20, CD21, CD22, CD34, CD45, PCA-1, IgM, and HLA-DR. Analysis of six separate fetal BM specimens indicated that combinations of cell surface antigens were expressed on analogous populations in fetal and adult BM. Consistent with adult BM, greater than 95% of TdT+ cells within the CD10+ population were CD34+, whereas less than 5% were CD34-. This CD10+/CD34+/TdT+ population constituted 30-40% of the total B cell compartment, compared with 10% in adults. Quantitative changes in CD45 expression on fetal BM B cells defined three clear populations, as has been observed in adults. In striking contrast to adult BM, greater than 95% of CD19+ and greater than 95% of surface IgM+ cells were CD10+, indicating that CD10 is a pan-B cell antigen in fetal BM. Virtually no mature B cells expressing CD21, CD22, or PCA-1 were detected in fetal BM. Our results indicate a preponderance of immature phenotypes exist in the fetal BM B cell compartment. These immature cells can be grouped into three distinct populations, and probably correspond to expanded populations found less frequently in adult BM. This striking increase in the earliest identifiable stages of B cell ontogeny is consistent with an active expansion of cells destined to constitute the humoral immune system during fetal development.

Antigens, CD↗
PubMed1990

Analysis of expression and function of CD40 on normal and leukemic human B cell precursors.

CD40 was originally identified on circulating and tonsillar human B cells, and anti-CD40 monoclonal antibodies (MoAb) are known to deliver a progression signal to activated B cells. However, the expression and function of CD40 on human B cell precursors (BCP) have not been examined in detail. Two new anti-CD40 MoAb were produced and shown to recognize an epitope indistinguishable from the anti-CD40 antibody G28-5. CD40 was readily detected on normal and leukemic BCP by flow cytometry, and cell surface expression was upregulated by phorbol ester. Despite the ability of normal and leukemic BCP to respond to phorbol ester (PMA) and/or low molecular weight B cell growth factor (L-BCGF), anti-CD40 exerted no stimulatory action and could not enhance the response of these cells to PMA, L-BCGF, or both. Cross-linking anti-CD40 MoAb with rabbit anti-mouse Ig also failed to induce a proliferative response in normal BCP. We conclude that anti-CD40 does not exert demonstrable agonistic effects on normal and leukemic human BCP. Our results suggest that signal delivery through CD40 and/or subsequent intracellular signal processing may require accessory molecules not expressed in BCP, or CD40 may subserve a different function for BCP.

Antibodies, Monoclonal↗
PubMed1979

Childhood leukemia-lymphoma. Heterogeneity of phenotypes and prognoses.

Results are reported on 724 children and adolescents with acute leukemia-lymphoma. One hundred patients had immunologic marker analysis that defined the major phenotypic groups, i.e., T-cell, B-cell (Burkitt), myeloid, and the most frequent form, non-T, non-T "common" or "undifferentiated" acute leukemia. Pre-T, pre-B, and "null" leukemias are included in the latter group. Response to therapy and survival was best in non-T, non-B acute lymphocytic leukemia, intermediate in T-cell disease, and worst in B-cell (Burkitt) disease. Additional factors resulting in decreased survival include elevated peripheral leukocyte count, presence of enlarged nodes, less depression of hemoglobin and platelets, and age greater than 7 years (all associated with 'lymphomatous" disease). Other factors resulting in decreased survival include age under 3 years and depression of serum immunoglobulins. Definition of the heterogeneity of childhood leukemia-lymphoma dictates differing forms of therapy for the various types of these diseases.

Adolescent↗