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G Janossy

Publications and source records attributed to G Janossy.

At least 145 records · Page 8Linked to original sources
PubMed1987

What kind of morphologically recognizable haemopoietic cells do we inject when doing foetal liver infusion in man?

There is no agreement, how to define the age of the embryo/foetus. From the 15th (fertilization) week onwards the whole foetal liver contains some 10(9) free haemopoietic cells. Before, and up to the 30th-34th weeks, the liver is the main site of haemopoiesis. The differential of embryonic smears (up to wk 9) differs from that of foetal ones. The first invasion of circulating primitive erythroblasts seeding in the liver (early 5th wk) is accompanied by the appearance of a lot of sinusoidal macrophages. Definitive erythropoiesis expands during the 6th-7th wks. Granulocytic representation peaks at 15-16 wks. Megakaryocytes are small and have few nuclei/nuclear lobes. Five to 8, or even more per cent of single haemopoietic cells were lymphoid-like cells in the 5th-6th wk liver smear. These cells precede the development of any lymphoid structure in the foetus. Ordinary lymphocytes amount to less than 2% between 10 and 18 wks, and reached 3% at wk 24. Percentage of dyserythropoietic nuclei in smears has been used to decide whether the injected cells could be regarded as 'physiological' cells. Ten out of 11 apparently healthy foetuses, delivered by hysterectomy/hysterotomy for maternal interest, aged 10 1/2 to 20 1/2 weeks, had mean 4.5% liver dyserythropoiesis. Extremely high dyserythropoiesis was associated with multilineage, instead of overwhelmingly erythroid haemopoiesis.

Cell Differentiation↗
PubMed1987

Elimination of T cells from human peripheral blood and bone marrow using a cocktail of three anti-T cell immunotoxins.

Four anti-T cell monoclonal antibodies were coupled to ricin-A and tested for their ability to kill T cells in peripheral blood and bone marrow using a clonogenic assay to quantify T cell survival. The immunotoxins (IT) prepared from RFT11 (CD2) and WT1 (CD7) antibodies were the most toxic to peripheral blood T cells. The immunotoxin prepared from RFT1 (CD5) was the next most efficient toxin and the immunotoxin prepared from RFT8 (CD8) was the least toxic. When these reagents were applied to peripheral blood cells at 3 x 10(-8) M the number of T cell colonies was reduced by an average of 95%, 94%, 84% and 50%, respectively. Peripheral blood T cells from different donors showed marked variability in their sensitivity to ITs. However, a cocktail of three ITs prepared from RFT11, WT1 and RFT1 gave superior and consistent killing (mean 99.9%; range 99.8-100%) of peripheral blood T cells from six donors. When this cocktail was applied to bone marrow cells from six donors, an average of 99.6% (range 99.5-99.8%) of the T cells were killed. Under the same conditions there was little or no reduction in the number of normal haematopoietic progenitors (CFU-GM, CFU-GEMM, CFU-Meg and BFU-E).

Antibodies, Monoclonal↗
PubMed1987

Monoclonal antibodies to human immunodeficiency virus: their relation to the patterns of lymph node changes in persistent generalized lymphadenopathy and AIDS.

Recently there has been much interest in using immunohistology with monoclonal antibodies (MABs) against different cells of the immune system in lymph nodes (LNs) of patients with HIV infection. The panel of these MABs is becoming increasingly extensive. In this study we report on our finding that by using a limited number of properly chosen MABs, diagnostically and prognostically relevant parameters can be acquired. One hundred and twenty-one LN biopsy specimens from patients with HIV infection were reviewed and classified according to our expanded working classification and a fifth main type of LN lesion, the small lymphocyte follicular type, was added to our earlier classification. We propose that this new type represents a transitional form between the mixed follicular type and the follicular depleted type. In the follicular type of LN lesion there is no marked change in the number of CD4 cells within the follicles and in the extrafollicular parenchyma. The reaction against the major core proteins of HIV is always positive and the number of proliferating cells is very high. The positivity is weaker in the earlier cases and stronger in the older ones. The follicular dendritic cell (FDC) network shows degenerative changes. In the hypervascular follicular type the reaction pattern with these selected MABs is very similar to the one in the follicular type. In the mixed type there are hyperplastic follicles and regressively transformed follicles in the same node. The hyperplastic follicles show a pattern similar to those in the follicular type. However, the reaction with MABs against core proteins of HIV is often markedly stronger. The number of proliferating cells is decreased markedly. Some follicles show extensive FDC network destruction. CD4 cells within the follicles and in the extrafollicular parenchyma are decreased. The regressively transformed follicles contain very few proliferating cells and the reaction with MABs against core proteins is variable, being strong in some follicles and weak in others. The small lymphocyte type contains follicles consisting mainly of small lymphocytes. These lymphocytes are of the same phenotype as those in the primary follicles. In contrast to these, however, the numbers of CD4 and Leu 7+ cells are much decreased. The reaction with MABs to core proteins is weak and limited to the germinal centres (GCs). The number of proliferating cells is strongly diminished. The FDC network, however, is well developed in most follicles. In the follicular depleted LNs there are no follicles; however, in some LNs remnants of FDC can be seen.

AIDS-Related Complex↗
PubMed1987

CD5-positive B cells after T cell depleted bone marrow transplantation.

CD5 is an antigen normally found on T cells and on a minority subpopulation of B cells in fetal spleen and tonsil and on the majority of cells in B-chronic lymphocytic leukaemia. Recent reports described the occurrence of large numbers of CD5-positive B cells in the peripheral blood after bone marrow transplantation (BMT). We examined the peripheral blood for CD5-positive B cells in 21 patients who underwent allogeneic BMT for leukaemia with marrow first depleted of T cells using anti-T monoclonal antibodies and complement mediated lysis. Twenty-six samples were obtained from patients 24-644 days after BMT and examined for the existence of blood-borne CD5-positive B cells by immunofluorescence analysis microscopically and by flow cytometry. The number of CD5-positive B cells was consistently lower than 2%. The absence of CD5-positive B cells in this series may be due to the method of T cell depletion of the marrow or to methodological differences in the analysis of the cells.

Adolescent↗
PubMed1987

Enrichment of human marrow T-cell precursors by complement-dependent cytotoxicity with monoclonal antibodies and Percoll Gradient centrifugation.

Attempts to enrich and characterize human marrow T-cell precursors have been performed using discontinuous Percoll gradient centrifugation, phenotypic analysis of cells with monoclonal antibodies (Mabs), and T-cell colony-forming capacity. Marrow cells were extensively depleted of T cells and separated into seven fractions. The depletion was performed with the following Mabs: CD6 (MBG6 or RFT12) + CD8 (RFT8), CD2 (D66) + CD8 (RFT8), and CD6 (RFT12) + CD8 (RFT8) + CD7 (RFT2). A peak of cells with the capacity to differentiate into mature CD2+CD4+ T-cell agar colonies (TL-CFU) was obtained in a fraction with a density 1.063 less than d less than 1.069 g/ml. This peak was associated with the presence of cells expressing RFB1 and OKT10, two markers shared by hemopoietic precursors. Cells in this fraction were negative for CD3, CD4, CD1, CD8, and CD2 antigens. Their treatment by complement-dependent cytotoxicity with the CD7 Mab resulted in a loss of T-cell colony-forming capacity together with a reduction of T10-, RFB1-, and My10-positive cells.

Antibodies, Monoclonal↗
PubMed1987

Rearrangement of immunoglobulin and T cell antigen receptor genes in acute myeloid leukemia with lymphoid-associated markers.

Ten cases of adult acute myeloid leukemia (AML) displaying lymphoid-associated markers CD7 and/or terminal deoxynucleotidyl transferase (TdT) have been investigated for rearrangement of immunoglobulin and T cell antigen receptor beta and gamma genes. Two of six TdT+ cases had clonally rearranged Ig genes, whereas six of eight CD7+ AMLs, including three that were TdT+, had a germ line configuration of both immunoglobulin and T cell receptor beta and gamma genes. A single case of CD7+ TdT- AML had clonal rearrangement of all three genes. These results indicate that expression of TdT and/or CD7 is not accompanied by gene rearrangement in most cases of adult AML. A minority of cases, displaying lymphoid-associated phenotypic markers and accompanying gene rearrangement, may represent a distinct subgroup of AML that arises from a rare, primitive stem cell, possessing extensive multilineage potential.

Adult↗
PubMed1986

Prevention of graft failure by an anti-HLFA-1 monoclonal antibody in HLA-mismatched bone-marrow transplantation.

Seven patients with immunodeficiencies (Wiskott-Aldrich syndrome, combined immunodeficiency, and osteopetrosis) were given a mouse monoclonal antibody against the alpha subunit of human leucocyte functional antigen (HLFA-1; CD18) to facilitate the engraftment of mismatched haploidentical related-donor bone marrow. Other conditioning included busulphan, cyclophosphamide, and antilymphocyte globulin. To prevent graft-versus-host disease the bone-marrow T cells were depleted with sheep erythrocyte rosetting and cyclosporin therapy was given. HLFA-1 antibody injections were well tolerated without side-effects except slight, transient fever (38-40 degrees) after the first injection. Engraftment was rapid in all seven patients. The regenerating leucocytes were of donor origin in all cases, and two patients have a mixed chimera. Two patients died from infections. The others are alive and well 60-395 days after transplantation. In a historical control group given the same treatment without anti-HLFA-1 infusion, only one of seven transplants partially engrafted; only two patients remain alive with autologous reconstitution but with uncorrected immunodeficiency.

Antibodies, Monoclonal↗
PubMed1986

Separate ontogeny of two macrophage-like accessory cell populations in the human fetus.

Human macrophage-like accessory cells were analyzed as they emerge in the absence of extrinsic antigens during fetal development. Monoclonal antibodies to monocytes/macrophages were used in combination with antibodies to HLA class II molecules. In the yolk sac and mesenchyme sampled at wk 4 to 6 of fertilization age, cells with dendritic morphology formed two populations distinguishable by phenotypic criteria: type i (majority) carried both macrophage-associated (RFD7+) and monocyte-associated markers (UCHM1+) but no detectable HLA-DR antigen, and type ii (minority) constitutively expressed class II (HLA-DR and -DP) but no RFD7 and UCHM1. The emergence of this heterogeneity preceded the formation of both thymus and bone marrow. During additional development, type i and type ii cells seeded to different microenvironments and underwent some additional phenotypic changes. Cells of type i, the RFD7+ population with high lysosomal (acid phosphatase) activity, were seen in the thymic cortex, marginal zone of lymph nodes, splenic red pulp, and in the midst of erythropoietic activity within the bone marrow. These cells were UCHM1- and class II-. Cells of type ii formed the population of HLA-DR+, RFD7- interdigitating cells, early inhabitants of T cell areas in the developing thymic medulla, lymph nodes, spleen, and tonsil. The Type ii cells that had already settled in their nichès expressed not only HLA-DR and -DP but also HLA-DQ, and another class II antigen identified by the antibody RFD1, which shows the restricted tissue distribution of HLA-DQ, but is governed by genes that are outside of and telomeric to the HLA-DQ region (or HLA-DR). Finally, subpopulations of macrophages (RFD7+, acid phosphatase-positive) in the fetal gastrointestinal and hepatic systems were HLA-DR+; the latter appear to include precursors of Kupffer cells in the developing liver.

Acid Phosphatase↗
PubMed1986

Human leukocyte function-associated antigens on lympho-hemopoietic precursor cells.

The expression of human leukocyte function-associated antigens (HLFA, equivalents of murine LFA-1) was studied on early lympho-hemopoietic cells in infant thymus and normal bone marrow by double immunofluorescence methods, cell sorting and colony-forming assays. Monoclonal antibodies MHM-24 recognizing the alpha chain (180 kDa) and 60.3 and 60.1 identifying the beta chain (95 kDa) were used. The vast majority of thymocytes including large terminal deoxynucleotidyl transferase (TdT)-positive blast cells are HLFA positive. On the other hand, most B cell precursors in the bone marrow, identified by the expression of nuclear TdT, do not show surface HLFA which appears at the pre-B cell stage (cytoplasmic mu positive, surface Ig negative). Cell sorting experiments revealed an enrichment of early myeloid cells (myeloblasts and colony-forming unit cells) in the HLFA-negative fraction. Erythroid cells appeared to be completely negative from the burst-forming unit erythrocyte stage onwards. Anti-HLFA-antibodies, capable of blocking T cell and natural killer function, may have therapeutic potential without interfering with precursor cell development in man.

Antibodies, Monoclonal↗
PubMed1986

Myasthenia gravis: immunohistological heterogeneity in microenvironmental organization of hyperplastic and neoplastic thymuses suggesting different mechanisms of tolerance breakdown.

Four samples of thymoma obtained from patients affected by myasthenia gravis have been immunohistologically analysed on cryostat sections using a panel of antisera and monoclonal antibodies specific for antigens which define different stages of intrathymic lymphocyte differentiation and antigens specific for different types of thymic epithelial cells (cortical, medullary). When the thymoma samples were compared to age-matched normal thymuses and hyperplastic thymuses obtained from patients with myasthenia gravis some evident microenvironmental differences could be demonstrated using these reagents. In all the thymoma samples in fact the neoplastic lobules appeared as grossly enlarged cortical-type areas, formed by accumulations of T lymphocytes exhibiting the cortical immature phenotype (TdT+, T6+, etc.) within a network of putatively neoplastic epithelial cells characterized by cortical phenotype as defined by reactivity with various monoclonal antibodies (RFD4-, MR3+). These 'cortical' epithelia showed some abnormal features such as lack or irregular distribution of HLA-DR and enhanced keratin expression. Small areas of 'medullary' differentiation could be observed in 3/4 thymoma samples. In thymic hyperplasia, on the other hand, the cortical areas appeared somewhat compressed (but comparable to those observed in normal age-matched samples) by enlarged medullary areas. The expansion of medullary areas was due to the infiltration of 'peripheral' lymphoid tissue intruding through the extraparenchymal zone and forming organized B and T areas. These observations are discussed in the light of the clinical heterogeneity observed in myasthenia gravis.

Adolescent↗
PubMed1986

Graft rejection following HLA matched T-lymphocyte depleted bone marrow transplantation.

Bone marrow graft rejection following HLA-matched bone marrow transplantation (BMT) for leukaemia has been a rare problem. However, with the introduction of T-lymphocyte depleted BMT, graft rejection is recognized as a new complication. At the Royal Free Hospital (RFH) in London T-depletion is achieved using two monoclonal antibodies with complement mediated lysis. The methodology was extended to other centres and in total 56 patients have received T-depleted, HLA matched BMT. Twelve of 56 patients have had graft rejection. At the RFH three of 41 (7%) patients have had rejection whereas at collaborating centres nine of 15 (60%) patients have had rejection. We have investigated these rejections in order to identify factor(s) responsible. Rejection was not restricted by patient or donor characteristics, nor disease status. Patient management, chemotherapy conditioning, efficiency of T-depletion, graft versus host disease (GvHD), and infection post BMT, were not consistently implicated. The major difference between the RFH and all other centres was in the radiotherapy (RT) conditioning: The RFH prescribed a single fraction of 7.5 Gy total body irradiation (TBI) whilst collaborating centres gave 10 or 12 Gy fractionated TBI. We conclude that the different incidence of rejection (7% v. 60%) relates primarily to the RT conditioning although the mechanisms(s) of rejection remain unknown. We conclude that where T-depleted BMT is used, compensation by more intensive RT conditioning is required in order to avert graft rejection.

Adolescent↗
PubMed1986

Platelet-derived growth factor stimulates growth of highly enriched multipotent haemopoietic progenitors.

Platelet-derived growth factor (PDGF) has been shown to stimulate growth of normal and malignant fibroblasts, glial cells and smooth muscle cells. A growth promoting effect on human haemopoietic precursors has also been described, but the interpretation of this haemopoietic proliferative response to PDGF has been hampered by the lack of purity of the target population. In this study we show that PDGF promotes growth of early bone marrow haemopoietic progenitors depleted of either monocytes or T lymphocytes which are known to influence haemopoiesis. Moreover, the action of PDGF is even increased on a highly enriched BI-3C5 early bone marrow population. BI-3C5 is a novel monoclonal antibody which recognizes an antigen present on all multilineage colony-forming cells (CFU-mix) (Tindle et al. 1985). BI-3C5 positively and negatively sorted fractions were obtained by fluorescence activated cell sorting (FACS) and PDGF was found to stimulate growth of CFU-mix in the BI-3C5-positive fraction (consisting of only 4-6% of the marrow population), the effect being more marked than that on unsorted bone marrow. The results suggest that the product of the cellular proto-oncogene c-sis (the putative structural gene for the beta chain of PDGF) may play a regulatory role in the in vivo proliferation of multipotent haemopoietic progenitors.

Adult↗
PubMed1986

Standardization of T-cell depletion in HLA matched bone marrow transplantation.

The IBM 2991 Blood Cell Processor has been used to isolate a mononuclear cell (MNC) fraction from the marrow of 31 allogeneic donors. The MNC fraction was then incubated with a combination of two murine monoclonal antibodies MBG6 (CD6) and RFT8 (CD8) followed by two rounds of treatment with rabbit complement resulting in a marrow inoculum significantly reduced in the number of T-lymphocytes. We report here new specifications for the use of Ficoll-Metrizoate, the method used to calculate T-lymphocyte depletion and the details of our attempts to improve T-depletion. Following marrow transplantation with this T-depleted fraction, 29 patients are evaluable for engraftment, one patient failed to engraft and one died too early for evaluation. Twenty-two had no acute graft-versus-host disease (aGvHD), at a minimum of 60 d, six had grade I acute GvHD and one grade III. No correlation was found between the absolute number of MNC infused and time to engraftment, nor any relationship between the number of residual viable T-lymphocytes in the infused marrow and the incidence of GvHD, but the patient with the most severe aGvHD also had the highest number of T-lymphocytes infused.

Antibodies, Monoclonal↗
PubMed1986

Discrimination of human macrophages and dendritic cells by means of monoclonal antibodies.

Two monoclonal antibodies (MoAb), RFD1 and RFD7, have been used to investigate whether human macrophages and dendritic cells represent phenotypically distinct cell types. RFD7 recognizes a 77 kd antigen, and is specific for acid phosphatase positive tissue macrophages, while RFD1 recognizes a unique Class II antigen, which is associated with dendritic cells. With immunohistological/cytological methods it was found that neither of these reagents reacted with granulocytes, monocytes, or lymphocytes, with the exception that a small proportion (less than 20%) of B cells were stained with RFD1. In tissues, RFD7 reacted with mature macrophages only and did not stain Langerhans cells in the skin or the interdigitating (dendritic) cells of the T-cell zones of lymphoid tissue and the thymic medulla. Conversely, RFD1 appeared specific for the interdigitating (dendritic) cells and did not react with macrophage populations identified morphologically, geographically, and histochemically in any tissue studied. When peripheral blood monocytes (RFD1-, RFD7-) were matured in vitro, two distinct populations of RFD1+ RFD7- and RFD7+ RFD1- cells emerged. It is concluded that in normal tissues these two reagents identify phenotypic differences between macrophages and dendritic cells that may have functional significance.

Antibodies, Monoclonal↗