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Biomedical subjects

D N Hart

Publications and source records attributed to D N Hart.

At least 109 records · Page 6Linked to original sources
PubMed1991

Busulphan/cyclophosphamide conditioning for bone marrow transplantation may lead to failure of hair regrowth.

Following the introduction of bulsulphan and cyclophosphamide (BUCY) conditioning in our unit in 1987, a number of patients noted incomplete scalp hair regrowth following bone marrow transplantation (BMT). Between August 1987 and May 1989, 22 patients had undergone allogeneic or autologous BMT in our unit and we recalled for detailed assessment the 14 who were alive and well at least 6 months post grafting. Six patients had experienced incomplete hair regrowth of varying severity 7-27 months following BMT. All those affected had received BUCY conditioning and the four most severely affected were allogeneic BMT recipients. No patient had received any post-BMT chemotherapy or radiation. None of the patients had evidence of graft-versus-host disease. No laboratory test abnormalities distinguished the affected from the unaffected patients. Despite the relatively small number of patients, our results suggest that BUCY has caused permanent damage to the hair follicles of the affected patients. Prolonged alopecia may markedly impair the quality of life for long-term survivors of BMT and this unexpected complication also has significant medicolegal implications.

Adolescent↗
PubMed1990

Cerebrospinal fluid B2-microglobulin levels in meningeal involvement by malignancy.

Cerebrospinal fluid (CSF) and serum B2-microglobulin (B2m) levels were measured prospectively in 63 patients with hematological malignancies and 14 patients with solid tumours to evaluate the correlation between elevated levels and malignant infiltration of meninges. Serial CSF B2-m levels were also measured in 18 patients who received prophylactic intrathecal cytotoxic treatment. CSF B2-m levels were significantly higher in patients with central nervous system (CNS) involvement than in those without (p less than 0.001). A CSF B2-m level greater than 1.80 mg/L was closely associated with CNS disease (specificity 96%, sensitivity 76%) and CNS infiltration was also likely when the CSF B2-m level exceeded a simultaneously drawn serum level (specificity 98%, sensitivity 46%). Intrathecal methotrexate prophylaxis resulted in a consistent and significant rise in CSF B2-m levels with an average increase of 96% during a course of intrathecal injections. These results suggest that CSF B2-m levels may not be helpful for predicting early CNS relapse in these patients. However the CSF B2-m level and the corresponding serum B2-m level is a useful adjunct to the cytological diagnosis of CNS involvement by malignancy at presentation. Its value in predicting early CNS relapse and documenting response to CNS treatment requires further clarification.

Adolescent↗
PubMed1990

Interstitial dendritic cells.

Interstitial dendritic cells (IDC) were first identified in the interstitium of non-lymphoid organs as leucocytes which stained intensely with anti-MHC class II antibodies. These cells have been identified in several species including man, and can be distinguished from tissue macrophages by their immunological phenotype and cytochemical and functional characteristics. IDC appear to be closely related to lymphoid dendritic cells (DC), and have the capacity to bind antigen and stimulate T lymphocyte responses. It seems probable that they represent a stage of nonlymphoid dendritic cell differentiation necessary for antigen surveillance, similar to the Langerhans cell of the skin. Exposure to antigen appears to induce migration of these cells into adjacent lymphatics and subsequent localization in the interfollicular areas of lymph node, where the DC present processed antigen to activate a primary T cell response. The IDC has been identified as the passenger leucocyte within organ allografts which contributes substantially to graft immunogenicity, so that eradication of donor organ IDC improves organ graft survival.

Animals↗
PubMed1990

Anti-leucocyte common (CD45) antibodies inhibit dendritic cell stimulation of CD4 and CD8 T-lymphocyte proliferation.

Dendritic cells (DC) act as primary antigen-presenting cells and probably initiate T-cell responses via the formation of DC-T-cell clusters. Both DC and T cells express members of the leucocyte common (CD45) family of molecules as major cell membrane proteins. The possibility that the leucocyte common antigens (LCA) play a functional role in the cellular events of a primary T-cell response was tested, by examining the effect of CD45 antibodies on the T-cell proliferative response induced by stimulating with allogeneic DC in the mixed leucocyte reaction (MLR). The presence of individual CD45 monoclonal antibodies during the MLR inhibited T-cell proliferation only weakly, but a mixture of monoclonal antibodies against different epitopes of the LCA had a more profound inhibitory effect. The effect of the CD45 antibodies was maximal during the first 24 hr and preincubation experiments indicated that the major blocking effect occurred at the T-cell level, although some inhibition after preincubation with DC was noted. Purified allogeneic CD8 T-cell responses were more susceptible to inhibition than purified CD4 cell responses, but no difference in the inhibition of the CD45RA (CMRF-11) or CD45RO (UCHL1) LCA-positive T-cell subsets was observed. The presence of CD45 antibodies did not inhibit DC-T-cell clustering but reduced cluster stability, suggesting that certain epitopes of the LCA may be involved in the process of cell adhesion.

Antibodies↗
PubMed1990

CD45 molecule cross-linking inhibits natural killer cell-mediated lysis independently of lytic triggering.

The fact that certain CD45 [anti-leucocyte common antigen (LCA)] monoclonal antibodies (mAb) inhibit natural killer (NK) cell non-major histocompatibility complex (MHC)-restricted cytolysis led to the suggestion that these mAb block a 'trigger' for NK cell lytic activity. However, the discovery that the intracytoplasmic portion of the leucocyte common molecule has protein tyrosine phosphatase activity raises the possibility that the mAb initiate a direct inhibitory signal, independent of the triggering apparatus. To clarify this, we have tested the ability of CD45 antibodies to trigger NK cells and redirect cytotoxicity against mAb-producing hybridoma cells and autologous monocytes, an approach which has identified other cytotoxic trigger molecules. Peripheral blood NK cells failed to kill the CD45 antibody-producing hybridomas, although a CD3 antibody expressing hybridoma was susceptible to cytotoxic T-cell lysis. Furthermore, the CD45 mAb CMRF-12 + 26, 13.3 and HuLyM4 did not redirect lysis of autologous monocytes by NK cells, whereas the isotype-matched CD16 mAb did so. Bivalent CD45 antibody was necessary to block NK lysis of K562, as F(ab')2 but not F(ab') fragments of CMRF-12 + 26 antibody inhibited killing. Capping of the LCA appeared to correlate with the ability of the CD45 mAb to block killing, suggesting that cross-linking of LCA molecular isoforms on the NK cell surface is required for CD45 mAb to inhibit non-MHC-restricted cytolysis.

Animals↗
PubMed1989

Sequential half-body irradiation in lymphomatoid granulomatosis. Report of a case and an immunohistologic study.

A case is presented of a man with ulcerating skin nodules who was diagnosed by histologic and immunohistologic analysis of skin biopsy specimens as having lymphomatoid granulomatosis (LYG). Phenotypic studies showed the majority of the infiltrating cells to be activated CD4+ T-lymphocytes. The disease followed a rapidly progressive course and did not respond to treatment with cytotoxic chemotherapy. The patient developed life-threatening systemic symptoms and involvement of both upper and lower respiratory tracts. After treatment with sequential half-body irradiation he has been in complete remission for 3.5 years.

Adult↗
PubMed1989

An activation antigen on a subpopulation of B lymphocytes identified by the monoclonal antibody CMRF-17.

The identification of membrane molecules expressed on subpopulations of B lymphocytes is of potential significance because these molecules may be candidates for regulating the activation, proliferation and differentiation of B cells. A new monoclonal antibody, CMRF-17, which reacts with a subpopulation of tonsil B lymphocytes has been produced. The antibody did not react with T lymphocytes in tonsil or peripheral blood nor most peripheral blood B lymphocytes but did label erythrocytes and some platelets. In tonsil, the germinal centre cells, cells in the interfollicular region and endothelial cells were positive, but mantle zone B cells were negative. Double labelling experiments showed that CMRF-17 reacted with activated tonsillar lymphocytes. The antigen recognized by CMRF-17 was heat stable, resistant to treatment with proteolytic enzymes and neuraminidase and was shown to be a carbohydrate determinant on one or more glycolipids. These characteristics of the antigen recognized by CMRF-17 and its pattern of reactivity distinguish this antibody from other monoclonal antibodies recognizing B-cell activation markers. It was notable that of the B-lymphoid malignancies tested to date, including those of probable follicular origin, few stained with CMRF-17.

Antibodies, Monoclonal↗
PubMed1989

Human dendritic cells stimulate allogeneic T cells in the absence of IL-1.

Dendritic cells (DC), which express high-density HLA class II molecules, stimulate strong primary allogeneic T-cell responses via an interaction of the T-cell receptor with major histocompatibility complex (MHC) antigens (signal 1). It is not yet clear whether they also provide a second stimulus to the responding T cell in the form of the cytokine interleukin-1 (IL-1). To clarify this point, the ability of purified human tonsil DC to produce IL-1 and to stimulate allogeneic T cells was tested. No intracellular IL-1 alpha or beta was identified in DC comparable to that readily demonstrated in monocytes, and IL-1 release from lipopolysaccharide (LPS)-stimulated DC was not detected in either a biological assay for IL-1 or an ELISA assay for IL-1 beta. Furthermore, strong stimulation of allogeneic T lymphocytes by DC in the mixed leucocyte reaction (MLR) was noted to occur in the absence of IL-1 production, and this stimulation was not inhibited by polyclonal antisera to IL-1 alpha and IL-1 beta, which were known to inhibit IL-1-mediated thymocyte proliferation. Other HLA-class II-positive cell populations, namely peripheral blood monocytes and B cells, purified by methods which avoided DC contamination, were unable to stimulate allogeneic T cells with or without supplementary IL-1. We conclude that DC are very effective stimulators of T lymphocytes and that IL-1 is not required as a second signal for allogeneic T-cell responses.

Antibodies, Monoclonal↗
PubMed1989

Inhibition of non-MHC-restricted cytotoxicity by CD45 but not CD3 monoclonal antibodies in patients with large granular lymphoproliferative disease.

Nine patients with a lymphoproliferative disorder characterized by a persistent expansion of large granular lymphocytes (LGL) and an increased proportion of cells labelling with natural killer (NK) and T cell markers were identified. The six patients with an expansion of alpha beta CD3/TcR positive cells were shown to have rearranged T cell receptor (TcR) genes whereas three patients whose LGL lacked CD3/alpha beta TcR on the surface had no beta TcR rearrangement detected. Eight of the nine patients were shown to exhibit non-MHC-restricted cytotoxic activity against K562; this activity was inhibited by CD45 and CD45-associated monoclonal antibodies known to inhibit normal non-MHC-restricted cytotoxicity but not specific MHC-restricted cytotoxic T cell activity. In contrast, the CD3 monoclonal antibody OKT3 did not inhibit but redirected LGL non-MHC-restricted cytotoxicity against K562. Following modulation of the CD3 molecule, the LGL were still capable of cytolysis of K562 targets, but additional OKT3 could no longer redirect cytolysis. The data indicate that the CD3/TcR complex on the LGL clones in patients with large granular lymphoproliferative disease is not the receptor for antigen on K562 cells, although it retains functional capabilities. Thus the CD3/TcR positive subset appears to have bipotential cytotoxic characteristics involving additional unique receptors for non-MHC-restricted cytotoxicity.

Adult↗
PubMed1989

Nodular sclerosing, mixed cellularity and lymphocyte-depleted variants of Hodgkin's disease are probable dendritic cell malignancies.

The normal counterpart of the Reed-Sternberg cell and its mononuclear variant, collectively referred to as Hodgkin's cells (HC), remains controversial. The possibility that HC are malignant dendritic cells was tested by using a panel of 38 monoclonal antibodies to phenotype the cells from 16 cases of Hodgkin's disease (HD), excluding lymphocyte-predominant HD, and the Hodgkin's cell line L428. The results were then compared with the known phenotype of human dendritic cells. HC stained strongly for HLA Class I and Class II antigens. The leucocyte common antigen was weakly expressed in most cases. Expression of T and B cell markers was unusual, with the exception of the CD40 antigen which was found on a majority of HC. HC commonly expressed the CD11a, CR4 (CD11c), CD15, CD18 and a number of activation antigens but did not stain with a variety of macrophage-specific antibodies. The antigenic phenotype of L428 and the HC of case material were similar. This immunocytological analysis failed to support a lymphocyte or macrophage origin for HC. Instead the antigenic phenotype of the Reed-Sternberg cell and its mononuclear variant more closely resembles that of dendritic cells than of any other haemopoietic cell normally resident in lymph nodes.

Antibodies, Monoclonal↗
PubMed1988

Isolation and characterization of human tonsil dendritic cells.

Human dendritic cells were isolated from tonsils by density gradient separation followed by FACS IV sorting with mAbs to remove contaminating cell populations. The resulting dendritic cell population consisted of large cells with plentiful basophilic cytoplasm, lacking in granules but containing a prominent Golgi apparatus and numerous mitochondria. The cell membrane was irregular, and marked cell protrusions were obvious when stained with anti-HLA class II reagents. Their nuclei were irregular and often indented with a visible nucleolus. These cells were not phagocytic and stimulated autologous and allogeneic lymphocytes more effectively than other tonsil cell types in MLR. Phenotypic analysis of these cells confirmed that they expressed the leucocyte common antigen and stained strongly for HLA-class II antigens. Tonsil dendritic cells also coexpressed the LFA-1 alpha and LFA-1 beta chains but did not stain with a wide variety of anti-monocyte or anti-macrophage antibodies. The cells also lacked Fc and complement receptors and failed to stain with CD1 antibodies. Extensive testing with mAbs revealed only a few positive reactions, and these were consistent with reports of these antibodies staining interdigitating cells in tissue sections. This established that tonsil dendritic cells belong to the unique haemopoietic cell lineage of dendritic cells. No cytoplasmic staining of IL-1 alpha or IL-1 beta was demonstrated, although these lymphokines were readily detected in activated monocytes.

Antibodies, Monoclonal↗
PubMed1988

Characterization of interstitial dendritic cells in human liver.

Sensitive immunofluorescence and immunoperoxidase techniques were used to test an extensive range of monoclonal antibodies for reactivity with Kupffer cells and interstitial dendritic cells (DCs) in cryostat-cut sections of human liver. Leucocytes with a dendritic cell morphology were identified with CD45 (antileucocyte common) reagents in portal tracts, predominantly around bile ducts, and these cells stained strongly for the HLA-DP, DQ, and DR antigens. Kupffer cells stained less intensely with anti-class-II reagents, particularly anti-HLA-DQ. The interstitial DCs expressed the LFA-1 antigen but failed to stain with CD11b, CD11c, and the defined T and B cell CD antibodies; nor did they stain with antibodies to FcR1, FcR11, FcRIII, or the C3b receptor. Of the myeloid monoclonal antibodies available from the 3rd Leucocyte Differentiation Antigen Workshop, only Y2/131, Ki-M7, Ki-M8, and a minority of CD14 antibodies stained DCs, whereas Kupffer cells showed a wider reactivity with antimacrophage antibodies including those of workshop groups 11, 15, 16, and other unique antibodies. A 2nd probable DC population was identified in the liver capsule that had a similar phenotype to portal interstitial DCs. Although some minor phenotypic differences between liver portal DCs and the phenotypes of Langerhans cells and isolated tonsil DCs were noted, our results support the view that there is a unique hemopoietic lineage of DCs. The presence of DCs, which stimulate strong allogeneic T cell responses, in the portal triads is consistent with the fact that the histologic changes of graft-versus-host disease seen in bone marrow transplantation and the lymphocytic infiltrate in a rejecting liver allograft occur predominantly in the periportal region.

Antibodies, Monoclonal↗
PubMed1988

The tissue distribution of the 3 alpha-fucosyl-N-acetyl lactosamine determinant recognized by the CD15 monoclonal antibodies CMRF-7 and 27.

Two monoclonal antibodies, CMRF-7 and 27, which react with cells of the granulocytic series, were obtained from hybridomas cloned from separate fusions. Biochemical studies indicate that both antibodies are of the CD15 group and react with the antigenic determinant 3 alpha-fucosyl-N-acetyl lactosamine (hapten X) expressed on some glycolipids and several different granulocyte glycoproteins with a wide range of molecular weights. The antigen was found on some promyelocytes and more differentiated granulocytes, including neutrophils and some eosinophils, but not basophils. Monocytes, lymphocytes, and erythrocytes were negative for CMRF-7 but neuraminidase treatment revealed "cryptic" sites on monocytes and some lymphoid cells. The antibody CMRF-7 reacted with the majority of acute myeloid leukemia blasts in the FAB categories M2-M5 but less frequently with M1 blasts and was positive with only 5/43 acute lymphoid leukemias. Immunoperoxidase staining of other normal human tissues indicates that this determinant is found on a range of epithelial cells in skin, the gastrointestinal tract and the genitourinary system. In addition some parts of the central nervous tissue and some endocrine organs stained with these antibodies.

Antibodies, Monoclonal↗
PubMed1988

Hairy cell leukemia cells are relatively NK-insensitive targets.

The hypothesis that interferon alpha (IFN alpha) has its beneficial effects in hairy cell leukemia by activating natural killer cells against hairy cells was examined. Leukemic cells from patients with hairy cell leukemia were tested for their susceptibility to lysis by fresh and IFN alpha activated peripheral blood mononuclear (PBMC) cells from normal donors. All hairy cells tested were relatively insensitive to cytolysis by PBMC and IFN alpha activated PBMC. The low levels of 51Cr release obtained with a few donors was due to lysis of leukemic cells, not residual normal cells, and was mediated by a natural killer cell (T cell receptor independent) mechanism. Chronic lymphatic leukemic cells before and after treatment with phorbol ester were also resistant to cytolysis. Hairy cells were not susceptible to lymphokine activated killer (LAK) cells but were sensitive to lysis by antibody and complement. The insensitivity to cell mediated cytolysis against hairy cells was shown by cold target inhibition to be a lack of target recognition by NK cells.

Antibodies, Monoclonal↗
PubMed1988

HLA-DR-positive leucocyte subpopulations in human skin include dendritic cells, macrophages, and CD7-negative T cells.

The immunophenotypes of the HLA-DR-positive leucocyte populations in normal human skin were studied using an extensive panel of monoclonal antibodies, which included antibodies from the Third International Leucocyte Differentiation Antigen Workshop (3rd LDAW). Langerhans' cells (LC) in the epidermis stained with antibodies from CD15c, Groups 10, 12a, 12b and 15, of the myeloid panel and from CD39 of the B-cell panel. However, LC did not react with CD14 antibodies or 63D3, which are frequently used to stain tissue macrophages. In addition to epidermal LC (26 cells/linear mm) a significant population of CD1a-positive cells was identified in the papillary dermis (7 cells/linear mm of overlying epidermis). The dermal HLA-DR-positive leucocytes consisted of three cell populations. The most numerous cell type stained with antibodies to monocytes/macrophages. There were fewer, though substantial, numbers of T lymphocytes (mainly CD7-negative) and the least numerous was the population of CD1a-positive cells. The CD1a-positive cells and the population of dermal cells that stain with monocyte/macrophage markers are both potential antigen-presenting cells for the skin-associated immune system.

Adult↗
PubMed1987

Functional analysis of a clonal expansion of Leu 11 positive NK active lymphoid cells.

A female patient with an unusual lymphoproliferative disease associated with marked neutropenia has been observed for 36 months. The expanded cell population consists of large lymphocytes, many of which contain large azurophilic granules with acid phosphatase activity. These cells were T3, T8, T11 and Leu 11 positive but lacked the M1, T10, IL-2 receptor and HLA.DR antigens. The majority of these cells (60-70%) were also Leu 7 (HNK-1) positive. Strong natural killer (NK) activity was found in both the Leu 7 positive and negative cell populations. This cytotoxic activity was inhibited by monoclonal antibodies known to inhibit NK activity but was unaffected by antibodies which block T cell and T/NK cell cytotoxicity. Further functional analysis indicated that these cells suppressed normal T cell responses to mitogens, MLC responses and PWM induced B cell immunoglobulin synthesis. No effect on bone marrow progenitor cell growth was demonstrated. Antibody dependent cellular cytotoxic (ADCC) activity was barely detectable despite the presence of the Leu 11 antigen. Southern blot DNA analysis demonstrated clonal rearrangement of the T cell receptor beta gene thereby confirming that this variant of T gamma lymphoproliferative disease was a neoplastic condition.

Adult↗
PubMed1987

Monoclonal antibody purified beta 2-microglobulin: heterogeneity revealed by radioimmunoassay.

A monoclonal antibody, CMRF1, to human beta 2-microglobulin (beta 2m) was used to purify antigen to develop an in-house beta 2m radioimmunoassay. This immunoadsorption purified material was used to prepare a rabbit anti-beta 2m serum and was radiolabelled for the radioimmunoassay. The assay compared favourably with a widely used commercial radioimmunoassay but the immunological potency of the in-house standard was lower than that of the commercial reagent. This potency difference was not accounted for by antigenic denaturation. Subsequent two-dimensional gel electrophoresis revealed a second 12,000 dalton protein with a higher isoelectric point than beta 2m in the immunoadsorption purified material, which was also present, although in lesser amounts, in the commercial product. The different relative content of the additional 12,000 dalton protein appeared to explain the immunological potency difference between the in-house and the commercial standard. These results strengthen suggestions that there may be some heterogeneity or polymorphism in human beta 2m.

Antibodies, Monoclonal↗