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Biomedical subjects

W Knapp

Publications and source records attributed to W Knapp.

At least 163 records · Page 9Linked to original sources

Analysis of CD3-antibody-mediated inhibition of T-cell activation.

In this study the influence of a non-mitogenic anti-CD3 antibody on accessory cell-dependent antigen and mitogen-induced T-lymphocyte proliferation has been investigated. The antibody was found to completely inhibit PHA, Con A, PWM, and tetanus toxoid stimulation, with no effect on the proliferation induced by the calcium ionophore A23187. VIT3 completely abrogated the production of IL-2 by lectin-stimulated T cells. It had no effect, however, on the IL-2-dependent proliferation of preactivated T-cell blasts. In addition, the antibody was able to elevate free cytoplasmic Ca2+ levels within minutes after the addition to T cells. Detailed time kinetic analyses revealed that the time interval critical for inhibition was significantly dependent on the interaction between T cells and accessory cells. Under standard conditions, in the presence of 10% non-T cells as accessory cells 50% inhibition was still achieved when VIT3 was added to PHA-stimulated T cells as late as 8 hr after the onset of culture. Delayed addition or a decrease in the number of added accessory cells significantly prolonged this time period. Lectin-stimulated T cells can thus obviously be inhibited via CD3 as long as they have not received all signals including those delivered by accessory cells. Although the underlying mechanisms are not clear so far, the observation that VIT3 at the same time triggers an early cytoplasmic Ca2+ response might indicate that it thereby actively interferes with antigen and lectin-initiated activation processes.

Antibodies, Monoclonal↗

Class II antigens in Hashimoto thyroiditis. I. Synthesis and expression of HLA-DR and HLA-DQ by thyroid epithelial cells.

Aberrant expression of HLA-DR antigens on epithelial cells is seen in various organ-specific autoimmune disorders including Hashimoto thyroiditis (HT). Expression of HLA-DQ has so far not been demonstrated on these cells. We report here that thyroid epithelial cells (TEC) in HT, in addition to the known aberrant expression of HLA-DR, coexpress HLA-DQ antigens. Furthermore we provide evidence that class II antigens are synthesized by TEC themselves by demonstration of intracellular HLA-DR gamma-chain. These findings support the theory that TEC may be able to present (auto)antigens in vivo thus perhaps contributing to the perpetuation of thyroid destruction. As expression of class II antigens on TEC was never observed in non- or weakly infiltrated areas, we propose that infiltration by T cells is necessary to induce this aberrant expression of class II antigens.

Epithelium↗

Myeloid progenitor cells in the peripheral blood of patients with hairy cell leukemia and other "leukemic" lymphoproliferative disorders.

We assayed granulocyte-macrophage committed progenitor cells (CFU-GM), erythroid committed progenitor cells (BFU-E) and pluripotent hemopoietic progenitor cells (CFU-MIX) in the peripheral blood of patients with hairy cell leukemia (HCL), acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL). In 8 HCL patients retaining their spleens, the number of circulating CFU-GM, BFU-E and CFU-MIX were under the lower limits of normal controls in 6, 6 and 5 cases, respectively, and were in the lower normal ranges in the remaining cases. Six splenectomized HCL patients had generally more circulating progenitor cells than their nonsplenectomized counterparts. In the peripheral blood of 2 patients with ALL and 3 patients with CLL, progenitor cells of all types were markedly increased compared to their respective values in the blood of control subjects. Hairy cells from 2 HCL patients failed to inhibit CFU-GM, BFU-E and CFU-MIX derived colony growth from control peripheral blood mononuclear cells. In 3 HCL patients previously low circulating progenitor cells did not rise 5-7 months after RC-alpha 2-IFN treatment despite normalization of peripheral blood counts. Our results suggest that a reduction of the committed and pluripotent progenitor cell compartment might be at least in part responsible for the pancytopenia in the majority of patients with HCL.

Adult↗

Growth fraction of tumour cells and infiltration density with natural killer-like (HNK1+) cells in non-Hodgkin lymphomas.

Two markers for cells in the growth fraction, the T9 antigen (i.e. the transferrin receptor) and the T10 antigen were investigated in frozen tissue sections of 105 non-Hodgkin lymphomas (NHL). The results were correlated with the histological subtype and the pattern of tumour infiltration by reactive cells. Special attention was directed to the density of natural killer (NK)-like cells using the anti-HNK1 (Leu7) antibody since the transferrin receptor (tfr) or other growth-associated membrane structures may serve as target for NK cells. Our study confirms a relationship between number of tumour cells with the T9 marker and tissue infiltration by HNK1+ cells in NHL of low (chronic lymphocytic leukaemia, hairy-cell leukaemia, immunocytic lymphoma, centroblastic-centrocytic lymphoma) and intermediate (centrocytic and centroblastic lymphoma) but not in NHL of high malignant grade (immunoblastic and lymphoblastic lymphoma). Comparable results were obtained with the T10 antigen although the correlation was less close. The percentage of cells in the growth fraction, defined by the expression of the T9 and T10 marker, corresponded with prognostically unfavourable subgroups with the remarkable exception of follicular NHL of centroblastic-centrocytic type. This lymphoma showed high numbers of cells with the T9 and the T10 marker in a microenvironment resembling normal germinal centres in many aspects.

Antigens, Surface↗

[Clinical value of various classifications in adults with AML].

111 adults with acute myeloid leukemia were classified according to the morphological, immunological and cytogenetic features of their leukemic cells. A comparison was made between the clinical parameters on prognosis of these subgroups. Hemoglobin was the only parameter among all six FAB-subgroups to show a statistical significant difference. Other differences found applied to a few subgroups only. Again, immunologically or cytogenetically characterized subgroups did not show significant differences in clinical parameters or prognosis. Patients with pseudodiploid or hyperdiploid karyotype had a lower remission rate than the remainder. However, a cluster analysis in which all three classifications together with the clinical parameters were considered was best able to characterize groups with different prognosis.

Adolescent↗

[Lineage infidelity of leukemia cells].

We phenotyped 548 blast populations from patients with acute de novo leukemia with a panel of 27 monoclonal antibodies and an antiserum against the enzyme terminal deoxynucleotidyl-transferase (TdT). In 56 cases (10,2%) we found a marker profile consisting of both myeloid and lymphoid characteristics (biphenotypic) leukemia = interlineage infidelity). In 49 out of the 56 cases the blast populations were clearly related to the myeloid (n = 41) or the lymphatic (n = 8) system. In those blast populations only one characteristic of the other differentiation could be detected. However, in 7 cases more than one myeloid as well as lymphatic characteristics were found on the same blast cells. In 4 cases (0.7%) the immunological phenotyping indicated the presence of two separate blast populations. The occurrence of a stem cell leukemia, an abnormal derepression of a genome, a defect of the membrane synthesis and the existence of a normal counterpart are taken into consideration as a cause of an "atypical" marker profile.

Acute Disease↗

Receptors for the third component of complement: their association with maturation stage in non-Hodgkin lymphomas (NHL) and their possible implication with the development of follicular structures.

In the majority of 188 non-Hodgkin lymphomas (NHL) investigated in this study, we found a simultaneous expression of the receptors for c3b and c3d (CR1 & CR2; cccorr = 0.69, P less than 0.0005). An analysis of the different histological entities of the Kiel classification revealed that this coexpression was most pronounced for germinal centre-derived (cccorr = 0.63, P = 0.0004) and immunocytic NHL (cccorr = 0.86, P = 0.0024), whereas in chronic lymphocytic leukaemias there tended to be a more heterogeneous pattern of complement receptor (CR) expression (cccorr = 0.29, P greater than 0.10). In contrast to these NHL of mid B cell stage, most of the NHL of early (i.e. acute lymphocytic leukaemia, lymphoblastic NHL) and late B cell stage (i.e. hairy cell leukaemia, immunoblastic NHL, multiple myeloma) did not express either of these receptors. CR positive NHL often showed a follicular arrangement of the neoplastic cells and had higher numbers of T helper/inducer (T4) lymphocytes (PCR1 less than 0.00005, PCR2 less than 0.05). Some cases of mid B cell NHL and all cases of hairy cell leukaemia reacted with antibodies against CR3 (i.e. the ic3b receptor).

B-Lymphocytes↗

Glycosphingolipid carriers of carbohydrate antigens of human myeloid cells recognized by monoclonal antibodies.

Six monoclonal antibodies with known specificities for the carbohydrate antigens i, X or Y, and seven anti-myeloid antibodies (determinants unknown) selected for their differing reaction patterns with human leucocytes were tested in chromatogram binding assays for reactions with myeloid cell glycolipids derived from normal human granulocytes and chronic myelogenous leukemia cells. Antigenicities were found exclusively on minor glycolipids which were barely or not at all detectable with orcinol-sulphuric acid stain. Among these, a neutral glycosphingolipid bound the anti-i antibody Den and chromatographed as the ceramide octasaccharide, Gal beta 1----4GlcNac beta 1----3Gal beta 1----4GlcNac beta 1----3Gal beta 1----4GlcNAc beta 1----3Gal beta 1----4Glc-Cer. Several species of neutral glycosphingolipids with six to more than ten monosaccharides were detected which carry the X antigen and others the Y antigen: Gal beta 1----4(Fuc alpha 1----3)GlcNAc and Fuc alpha 1----2Gal beta 1----4(Fuc alpha 1----3)GlcNAc, respectively. In addition, three new types of carbohydrate specificities were detected among the myeloid cell glycolipids. Two were associated with neutral glycolipids: the first, recognised by anti-myeloid antibodies VIM-1 and VIM-10, was expressed on a distinct set of glycolipids with six or more monosaccharides, and the second, recognized by VIM-8, was expressed on glycolipids with more than ten monosaccharides. The third specificity, recognised by the anti-myeloid antibody VIM-2, was expressed on slow migrating sialoglycolipids with backbone structures of the poly-N-acetyllactosamine type that are susceptible to degradation with endo-beta-galactosidase. Thus, we conclude that the i and Y antigens occur among the glycolipids of normal myeloid and chronic myelogenous leukemia cells and that a high proportion of hybridoma antibodies raised against differentiation antigens of myeloid cells are directed at carbohydrate structures.

Antibodies, Monoclonal↗

[Immunologic phenotypes of germinal center cell tumors].

A panel of monoclonal antibodies applied to frozen sections of non-Hodgkin's lymphomas was used to establish clear-cut differences among the different entities of malignant lymphomas of germinal centre cell origin. 51 cases (18 centrocytic, 25 centroblastic-centrocytic and 8 centroblastic lymphomas) were included in this study. A clear-cut difference in the expression of the T65 antigen (Leu 1+) and the common acute lymphoblastic leukaemia antigen (CALLA) was found. Thus, centrocytic lymphomas predominantly expressed Leu 1, but not CALLA, whereas centroblastic-centrocytic lymphomas were always positive for CALLA, but not for the T65 antigen. Centroblastic lymphomas are virtually never positive with respect to either antibody. These findings suggest that, perhaps, two different phenotypes of centrocyte exist in centrocytic and centroblastic-centrocytic lymphomas.

Adult↗

[Considerations on the therapeutic use of monoclonal antibodies].

The availability of monoclonal antibodies (MoAb) decisively improved and extended the analytical and diagnostic possibilities both in science and in clinical medicine. Monoclonal antibodies are also important tools for the isolation and purification of biologically active components. However, the therapeutic applications of monoclonal antibodies require manifold clarification. In this manuscript an attempt is made to present a short survey of the current stage of development in the therapeutic applications of MoAb and to discuss the foreseeable future in this research area. Possible fields of application, such as selective cell manipulation, drug targeting, detoxification by neutralization and/or immune clearance, specific antibody substitution are summarized and the negative and positive results so far achieved are discussed. Ex vivo therapy with monoclonal antibodies, which has already been used in a number of hospitals, is dealt with in detail. Problems already encountered, as well as anticipated in the course of the therapeutic implementation of monoclonal antibodies are discussed.

Antibodies, Monoclonal↗

Cross-reactivity between human hemopoietic cells and brain tumors as defined by monoclonal antibodies.

A battery of 24 monoclonal antibodies raised against human hemopoietic cells was tested in an indirect immunofluorescence technique on frozen sections of a variety of human neurogenic and non-neurogenic tumors. Twelve antibodies demonstrated some type of labeling of neurogenic tumors, frequently in patterns characteristic for benign and/or malignant gliomas and/or primitive neuroectodermal tumors (PNETs). Although also some cross-reactivity occurred in non-neurogenic tumors, the apparent operational specificity of some of our antibodies within the nervous system promises some aid in neuropathological tumor diagnosis; this was also demonstrated by combined use of some antibodies on smear preparations in which diagnosis by conventional stains was uncertain. This study confirms and expands previous data that sharing of antigenic determinants by hemopoietic cells and nervous system tumors is common. The significance of these cross-reactivities is at present a matter of speculation; cross-reacting autoantibodies might interfere with immune regulation in tumor patients, and an immune response might be initiated when glioma cells bearing Ia antigens present tumor-associated antigens to T cells.

Adolescent↗

Kinetics of activation antigen expression by in vitro-stimulated human T lymphocytes.

In this study a panel of monoclonal antibodies was used to investigate the kinetics of the appearance of activation-linked surface determinants as well as cytoplasmic and nuclear determinants in human T cells following lectin stimulation. Well known activation markers, such as Ia/DR, transferrin receptor, IL-2 receptor, T10, and gp24, were compared and investigated together with the T13 structure, recently found in this laboratory. T13, not demonstrable on resting T cells, could be seen within 24 hr after lectin stimulation. Kinetics of the appearance were similar to IL-2 receptor and transferrin receptor expression. Ia/DR synthesis was investigated separately for each polypeptide and the cytoplasmic invariant gamma-chain expression could be demonstrated for the first time with a gamma-chain-specific monoclonal antibody VIC-Y1. Moreover, gamma-chain synthesis seems to precede alpha- and beta-chain occurrence in human T cells. In addition, data from quantitative studies on antigenic densities are presented.

Antibodies, Monoclonal↗

Unexpected absence of a myeloid surface antigen (3-fucosyl-N-acetyllactosamine) in promyelocytic leukemia.

According to the criteria of the FAB classification we diagnosed acute promyelocytic leukemia in 19 out of 191 AML blast cell populations. The reaction pattern with the anti-myeloid monoclonal antibodies VIM2, MCS2 and MY9 and the MHC-class II antibody VID1 in all cases showed the characteristics which were expected from the normal granulopoiesis. The monoclonal antibody VIM-D5, which recognizes the myeloid cell surface structure 3-fucosyl-N-acetyllactosamine (3-FAL), was not reactive with the majority of promyelocytic blast cells, however. In 13 cases 3-FAL was not detectable and in 6 cases only low or moderate reactivity of VIM-D5 with blast cells was observed. The phenotype of leukemic promyelocytes thus differs from the majority of normal promyelocytes in this respect.

Antibodies, Monoclonal↗

Cell lineage heterogeneity in blast crisis of chronic myeloid leukaemia.

Blast cells from 45 patients with chronic myeloid leukaemia in blast crisis (CML-BC) were immunologically phenotyped with a panel of 26 monoclonal antibodies and studied for terminal deoxynucleotidyl transferase (TdT) content. Out of 45 blast-populations, 28 showed a myeloid, 14 a lymphoid, two a mixed and one an unclassifiable marker profile. In contrast to acute myeloid leukaemia (AML), we found frequent involvement of the thrombopoietic and erythropoietic systems in myeloid CML-BC. Furthermore, the marker profile on blast cells in myeloid CML-BC was different from that seen in AML. The blast cells in lymphoid blast crises of CML displayed the same lymphoid marker profile as those in acute lymphoblastic leukaemia. In three of 16 patients who were serially tested, we observed phenotypic changes in the blast cell populations. In one patient the blasts changed from lymphoid to myeloid type while remaining TdT-positive; in another case the blasts switched from granulomonocytic TdT-negative to granulomonocytic TdT-positive. In the third patient erythroid precursor cells appeared as the disease progressed. The results indicate the capacity of blast populations in CML-patients during blast crisis to differentiate along several pathways.

Adolescent↗

Deficiency of the autologous mixed lymphocyte reaction in patients with classic hemophilia treated with commercial factor VIII concentrate. Correlation with T cell subset distribution, antibodies to lymphadenopathy-associated or human T lymphotropic virus, and analysis of the cellular basis of the deficiency.

14 patients with hemophilia were studied for the distribution of T cell subsets, the presence of antibody to lymphadenopathy-associated or human T lymphotropic virus type III (LAV/HTLV-III), and their responsiveness in autologous mixed lymphocyte reactions. In addition, mitogen and alloantigen responsiveness and Interleukin-2 production were investigated. Seven patients were found to have low Leu 3a/Leu 2a (T4/T8) ratios; eight patients had antibody to LAV/HTLV-III; and an additional patient had acquired immunodeficiency syndrome. Responsiveness to mitogens and alloantigens as well as Interleukin-2 production were comparable with those of healthy individuals. However, patients with low ratio, many of whom had antibodies to LAV/HTLV-III, had a highly deficient autologous mixed lymphocyte reaction. This reduced response of T cells to autologous non-T cells could not be corrected by elimination of Leu 2a/T8 cells, which indicated that there was a preferential loss of the Leu 3a cell subset(s) which responded to autologous non-T cells. Thus, these patients have a deficiency of intercellular communication within their immune system.

Acquired Immunodeficiency Syndrome↗

Immunological features of nonimmunogenic hyperthyroidism.

Blood lymphocyte subpopulations (Leu 4+ cells = pan-T cells, Leu 3a+ cells = helper/inducer cells, and Leu 2a+ cells = suppressor/cytotoxic cells), thyroid-stimulating immunoglobulins, microsomal antibodies and antibodies against thyroglobulin were determined in 10 patients with hyperthyroidism due to single autonomously functioning thyroid nodules (ATN), 11 patients with hyperthyroidism due to Graves' disease (GD) and in 20 normal subjects. Thyroidectomy was performed in 8 of the patients with ATN and in 6 of those with GD after 3 weeks of antithyroid drug treatment with methimazole. Lymphocytic infiltration of thyroid tissue, the amount of the various lymphocyte subsets (Leu 4+, Leu 3a+, and Leu 2a+ T cells as well as B+ B cells) in the thyroid gland, as well as the expression of the histocompatibility antigen HLA-DR on thyrocytes and intrathyroidal lymphocytes were examined. Blood Leu 4+ cells were reduced due to a lack of Leu 2a+ cells in patients with ATN and GD when compared to normal subjects. Thyroid-stimulating immunoglobulins were detected in all patients with ATN and GD, but in none of the normal subjects. Lymphocytic infiltration of thyroid tissue was present in patients with ATN and GD. The various lymphocyte subsets in the thyroid gland did not differ between the two patient groups. DR expression on thyrocytes was seen in 6 of the patients operated for ATN and in 5 of those who underwent surgery for GD. Infiltration with DR+-T lymphocytes was found in all thyroid glands investigated. Thus immunological findings usually classified as proof for the autoimmune origin of GD exist also in patients with ATN. An overlap in the pathogenetic background of both diseases seems possible.

Adult↗