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J Naessens

Publications and source records attributed to J Naessens.

At least 55 records · Page 3Linked to original sources
PubMed1993

Cross-reactivity of workshop antibodies with cells from domestic and wild ruminants.

Reactivities of the monoclonal antibodies (mAbs) from the workshop panel with cells from cattle, sheep, goats, Cape buffalo (Syncerus caffer) and waterbuck (Kobus defassa) were tested. One hundred and sixty-nine mAbs reacted with bovine cells and 111 with sheep cells; 86 were shown to react with goat cells, 71 with buffalo cells and 70 with waterbuck cells. Some mAbs cross-reacted with all five ruminants tested, and are likely to react with epitopes that are conserved in other ruminant species. Such mAbs will obviate the need to produce mAbs panels to leukocyte antigens of other ruminants.

Animals↗
PubMed1993

The transferrin receptor in African trypanosomes: identification, partial characterization and subcellular localization.

All eukaryotic cells, including African trypanosomes, require iron for growth and division, and this iron is acquired by the receptor-mediated endocytosis of iron-loaded transferrin (diFe(3+)-transferrin). In trypanosomes transferrin (Tf) has been shown to be delivered into lysosomes and may not recycle back to the cell surface as it does in mammalian cells (Grab, D. J., et al., Eur. J. Cell Biol. 59, 398-404 (1992)). Here, we describe for the first time, the characteristics of a Tf-binding protein with receptor-like properties in Trypanosoma brucei brucei. Bloodstream forms of rodent-adapted T. brucei were incubated with [35S]methionine and detergent lysates chromatographed on a Sephacryl S-300 column. Fractions were incubated with anti-Tf serum to immunoprecipitate Tf/Tf-binding protein complexes. On sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) the molecular mass of the major protein in the immunoprecipitate was 88 to 92 kDa. Tf-binding proteins could also be isolated using diferric Tf-Sepharose. The molecular mass of the major Tf-binding protein, as estimated from Sephacryl S-300 column chromatography, in the presence of detergent, was approximately 90 to 100 kDa and 90 kDa with SDS-PAGE. Each 90 kDa Tf-binding protein was able to bind one molecule of diferric Tf. Since monoclonal antibodies to human and bovine Tf receptors failed to react with any trypanosome proteins, antisera were raised against the T. brucei Tf-binding proteins eluted from Tf-Sepharose at low pH. These antibodies recognized a 90 kDa protein on Western blots of a T. brucei lysate and inhibited the growth of T. brucei in vitro. Immunolocalization studies, using this antiserum showed that the Tf-binding protein was localized in the flagellar pocket and within the early endosomal compartments. In the presence of protease inhibitors there was additional localization in lysosome-like organelles. The Tf-binding characteristics and localization of this 90 kDa protein suggest that this molecule is a strong candidate as a physiological receptor for Tf in these parasites.

Animals↗
PubMed1992

Characterization and measurement of CD5+ B cells in normal and Trypanosoma congolense-infected cattle.

CD5+ B cells in cattle are present in peripheral blood and spleen, but not in lymph nodes, tonsils or Peyer's patches. Compared to classical B cells, they express similar levels of B cell surface markers, but have higher levels of surface IgM. We failed to find evidence for IgD on bovine B lymphocytes. The CD5+ B cells expressed CD11b (Mac-1). Another small subpopulation of B cells carried CD11b but not CD5. In cattle infected with Trypanosoma congolense, a dramatic increase in the percentage of CD5+ B cells in blood and spleen was observed. This increase occurred 7-10 days after parasites were first detected in the blood and correlated with the increase in serum IgM and the increase in the absolute number of B cells that is typical to trypanosome-infected animals. The increase in B cells was found to be due mainly to the expansion of the CD5+ B cell subpopulation. The cause of the amplification of the CD5+ B cells and their possible involvement in the production of autoantibodies and non-parasite-specific antibodies which have been described in trypanosome-infected animals are discussed.

Animals↗
PubMed1992

Selection of BoCD25 monoclonal antibodies by screening mouse L cells transfected with the bovine p55-interleukin-2 (IL-2) receptor gene.

The bovine interleukin-2 receptor-alpha (IL-2R alpha) gene has been isolated and a rabbit antiserum against a fusion protein of the gene has been produced. However, the antiserum does not inhibit IL-2-dependent proliferation. Since a panel of monoclonal antibodies (mAb) to bovine activation antigens was available, we transfected the gene into mouse L fibroblasts, selected stable transfectants with the rabbit antiserum, and screened for antibodies that bound the transfected cells but not the untransfected cells. Three mAb were selected and all three precipitated a molecule of M(r) 55,000 (under reducing conditions) from activated cells, as expected from homology with mouse and human IL-2R alpha (CD25, Tac). One of the three mAb was a strong inhibitor of IL-2-dependent proliferation of bovine lymphocytes. Thus, the availability of transfected cells allowed us to establish quickly and unequivocally the antigenic specificity of a number of antibodies.

Animals↗
PubMed1991

Characterization of bovine haemopoietic progenitor cells using monoclonal antibodies and fluorocytometry.

Monoclonal antibodies against bovine leucocyte cell surface differentiation antigens were used in combination with a fluorescence activated cell sorter to enrich bovine haemopoietic progenitor cells present in bone marrow cell populations prior to in vitro culture. After two sequential centrifugations of the bone marrow cell suspension through Ficoll-Paque, the interface fraction was stained with a cocktail of monoclonal antibodies directed against mature monocytes/macrophages, granulocytes and lymphocytes. Using appropriate electronic window settings on a FACStar Plus, cells with a high 90 degrees light scattering property (granular cells), a low forward light scattering property (erythrocytes and reticulocytes) and cells positive for monoclonal antibodies specific for lineage-restricted leucocyte markers were removed and the negative cell fraction collected. These negatively-selected cells were stained with monoclonal antibodies specific for a pan-leucocyte or a MHC class II marker and the positive cell population was collected in a second sort and subsequently submitted to culture. All erythroid and granulocyte/macrophage colony forming cells expressed MHC class II antigens, as well as the pan-leucocyte antigen. These same progenitors did not bind any of a variety of monoclonal antibodies directed against lineage-specific antigens on lymphocytes, granulocytes or monocytes/macrophages, although they did bind monoclonal antibodies recognizing MHC class I antigens. Between 85% and 91% of the isolated cells seeded were capable of forming erythroid or granulocyte/macrophage colonies within 5 to 10 days, thus increasing the plating efficiency of these cell types in bone marrow populations by at least 60 fold.

Animals↗
PubMed1991

Characterisation of lymphocyte populations in African buffalo (Syncerus caffer) and waterbuck (Kobus defassa) with workshop monoclonal antibodies.

In order to measure different lymphocyte populations in buffalo (Syncerus caffer) and waterbuck (Kobus defassa), we analysed the monoclonal antibodies from the 1st International Workshop on Leukocyte Antigens in Cattle, Sheep and Goats for suitable cross-reactive reagents. Peripheral blood mononuclear cells from three buffalo and three waterbuck were tested with the whole panel of monoclonal antibodies (mAbs) together with some additional antibodies against MHC and Ig. In some clusters almost all antibodies cross-reacted (CD2, CD8), in others almost none cross-reacted (CD4, CD5) and in cluster CD6, mAbs only reacted with buffalo but not waterbuck. Double staining experiments were performed on buffalo PBM with the cross-reacting antibodies, to confirm that they detected similar cell populations as in bovine PBM. This was shown with reagents against CD2, CD4, CD6, CD8, CD11, WC1, WC3 and Ig. The molecular weights of the buffalo antigens correlated well with those of the homologous cattle antigens. In the CD5 cluster, only one mAb reacted with the two wild species, and defined an unusual CD2+ CD5- cell population in buffalo. Also mAbs cross-reacting with buffalo MHC class II detected unusual expression on resting T cells. From the results presented, it is clear that the workshop panel contains mAbs against the most important T and B cell antigens of buffalo and probably waterbuck, which will allow us to compare functional lymphocyte populations in cattle and wild ruminants.

Animals↗
PubMed1991

Analysis of peripheral leucocyte populations in N'Dama and Boran cattle following a rechallenge infection with Trypanosoma congolense.

Monoclonal antibodies, flow cytometry and routine haematological techniques were used to analyse circulating leucocyte populations in trypanotolerant (N'Dama) and trypanosusceptible (Boran) cattle following a homologous rechallenge with Trypanosoma congolense clone IL13-E3. The N'Damas developed a low, transient parasitaemia and did not develop anaemia. The Borans became parasitaemic and developed chronic anaemia but three of the five animals eventually self-cured, whilst, a group of primary-challenged Borans experienced a severe infection characterized by high levels of parasitaemia and acute anaemia. During infection the numbers of circulating B-cells increased in all three groups from day 21 onwards. The proportion of B-cells expressing the CD5 antigen increased from pre-infection levels of 5-10% of B-cells to 49-90% by day 19 post infection in all three groups. The neutrophil count declined in both Boran groups but not in the N'Damas. The CD4+ T-cell and gamma delta T-cell populations decreased in both Boran groups but did not alter significantly in the N'Damas. Although it was not possible to infer from the data, that the CD4+, gamma delta T-cell, neutrophil and erythrocyte populations were directly responsible for the differential control of the disease by the two breeds, it was possible to correlate alterations in these cell populations with the severity of the disease.

Animals↗
PubMed1990

Quantitation of bovine immunoglobulin isotypes and allotypes using monoclonal antibodies.

A panel of 10 monoclonal antibodies specific for bovine immunoglobulins M, A, G1, G2 and light chains were produced and enzyme-linked immunosorbent assays developed to measure Ig levels in body fluids and culture supernatants using this panel of MAbs. An inhibition ELISA was accurate and sensitive for MAbs of high affinity, detecting levels as low as 10 ng ml-1 of IgM using a high-affinity MAb, IL-A50 (dissociation constant = 1.3 X 10(-11) M). For MAbs of lower affinity (KD of less than 0.25 X 10(-9) M) a sandwich ELISA was more sensitive, detecting 0.1-1.0 microgram ml-1 Ig, provided a conjugate of an anti-light chain MAb was used. Using these ELISA techniques, four pairs of MAbs specific for bovine IgM, IgA, IgG1 and IgG2 respectively, were screened on sera from over 100 cattle of different breeds to determine whether any detected a polymorphic epitope. MAbs IL-A30, IL-A60, IL-A66, IL-A71, IL-A72, IL-A73 and IL-A74 were shown to recognise monomorphic determinants on their respective heavy chains. In contrast, the epitope recognised on the mu-heavy chain by MAb IL-A50, which had previously been shown to be polymorphic, was found to be allelic and inherited under the control of a single gene, probably Cu.

Animals↗
PubMed1990

Multiple aortic aneurysms: the results of surgical management.

During the past 2 decades 102 consecutive patients (77 men and 25 women) with multiple aortic aneurysms underwent 201 aortic reconstructions. These procedures (174 elective and 27 emergent) represented 3.4% of the 5837 aortic aneurysm operations performed. Seventy-five (30.9%) of the 243 aneurysms occurred in the infrarenal aorta, 65 occurred in the descending aorta (26.7%), 56 occurred in the thoracoabdominal aorta (23.0%), and 47 occurred in the ascending aorta or arch (19.3%). Ages ranged from 20 to 81 years (mean 63.3 years). Smoking history and abnormal electrocardiographic tracings were present in 84.3% of the patients, hypertension was present in 77.5%, and obstructive lung disease was present in 60.8%. Multiple aortic aneurysms were present at the time of the first repair in 55 patients (53.9%). Twelve patients had one procedure, 81 had two, and nine had three. Sixteen (17.8%) of the 90 patients who had multiple operations had a subsequent operation for complications of the unrepaired aneurysm (rupture 12, symptoms 4). Fourteen perioperative deaths occurred among the 174 elective repairs (8.0%), and 11 occurred among the 27 emergent procedures (40.7%). Procedure mortality increased with the ordinal number of elective operations and was 4.4% for the first, 10.4% for the second, and 33.3% for the third. Seven of 21 patients (33.3%) who had simultaneous repair of at least two aortic aneurysms died in the perioperative period. Overall, 77 of the 102 patients (75.5%) survived all surgical procedures to repair their multiple aortic aneurysms; of these, 63 had complete resection of all known aneurysms. Follow-up was complete in all patients and averaged 6.3 years (ranges: 1 month to 19 years). There were 30 late deaths; the most frequent cause was myocardial infarction. Kaplan-Meier 5-year survival including perioperative deaths for all patients after the first operation was 76% and after the last operation 40%. We conclude that multiple aortic aneurysms can be safely managed, usually with staged repairs, and that long-term survival is probably. After the first aortic operation the presence of multiple aneurysms mandates close observation with timely surgical intervention.

Adult↗
PubMed1990

Characterization of a bovine leucocyte differentiation antigen of 145,000 MW restricted to B lymphocytes.

A new bovine B-cell differentiation antigen is described that is detected by three monoclonal antibodies (mAb). The antigen is not an immunoglobulin and is precipitated from peripheral B cells as a molecule with an approximate molecular weight (MW) of 120,000 or 145,000 before and after reduction, respectively. Data obtained from two-colour cytofluorimetry and immunohistochemistry confirmed that the antigen was found only on mature B cells and on cells with dendritic morphology in the follicles of the organized lymphoid tissues. Its level of expression is directly correlated with that of IgM on peripheral blood B cells and Theileria parva-transformed B cells. The marker was also expressed on the peripheral cells which expressed surface IgG. Based on the antigen's cellular distribution, biochemistry and histochemistry, it is considered to be analogous to the human CD21 antigen.

Animals↗
PubMed1989

Demonstration of two allelic forms of the bovine T cell antigen Bo5 (CD5) and studies of their inheritance.

Two monoclonal antibodies (mAbs), CC17 and IL-A67, which are specific for the bovine equivalent of the CD5 antigen, Bo5, were each found to react with the cells of some animals but not others. The cattle tested were all positive for one or both of the mAbs, but the level of expression on cells expressing both determinants was slightly lower than that on cells expressing either of the determinants on their own. Both mAbs precipitated an antigen of 67 kD. However, sequential immunoprecipitation experiments with cells that reacted with both mAbs demonstrated that the determinants are present on two different sets of molecules. These findings suggested that the mAbs recognize two co-dominantly expressed allelic forms of Bo5. This was confirmed in family studies, with groups of full- and half-sibling offspring of sires and dams of defined phenotypes. These experiments also showed that the gene encoding the Bo5 antigen is not linked to the major histocompatibility complex (MHC). The frequencies of the two alleles, which have been designated Bo5.1 and Bo5.2, in the cattle populations tested were 100% and 0%, respectively, in Bos taurus, and 10% and 90%, respectively, in Bos indicus.

Alleles↗
PubMed1988

Monoclonal antibodies which react with bovine T-lymphocyte antigens and induce blastogenesis: tissue distribution and functional characteristics of the target antigens.

In this study we report on the tissue distribution and functional characteristics of bovine T-cell differentiation antigens recognized by the monoclonal antibodies (mAbs) IL-A26, IL-A27, and IL-A28. All three mAbs are able to stimulate proliferation of peripheral blood mononuclear cells (PBM) and inhibit proliferation of responder cells in mixed leucocyte cultures (MLC). MAbs IL-A27 and IL-A28 are believed to react with the same molecule, which is different to that recognized by IL-A26 as determined by a number of criteria. MAbs IL-A27 and IL-A28 inhibit binding of one another, but not of IL-A26. MAbs IL-A27 and IL-A28 react with 25% of thymocytes confined to the medulla, whereas IL-A26 reacts with approximately 80% of thymocytes, including medullary and cortical populations. MAbs IL-A27 and IL-A28 react with thymocytes which express BoT4 or BoT8 singularly, whereas IL-A26 reacts with all cells which express BoT4 or BoT8, either singularly or dually, in addition to all thymocytes which react with IL-A27/28. Only IL-A26 inhibits spontaneous sheep erythrocyte (E)-rosette formation by bovine T cells. Based on tissue distribution and functional characteristics, IL-A26 is believed to recognize the bovine homologue of CD2, designated BoT2, whereas IL-A27/28 reacts with a mature T-cell antigen. Cells reactive with the mAbs constitute approximately 60% of bovine PBM. Using these mAbs in dual immunofluorescence analyses, at least three populations of bovine T cells are demonstrable in PBM. The majority of T cells are BoT4+ or BoT8+ and also react with IL-A26/27/28. A second small population of PBM is negative for BoT4 and BoT8 but is IL-A26/27/28+. A third population (less than 5%) is BoT4-/BoT8-/ILA27/28- but reacts with IL-A26.

Animals↗
PubMed1988

Identification of isotypes and allotypes of bovine immunoglobulin M with monoclonal antibodies.

Epitopes specific for IgM on peripheral blood lymphocytes from 47 cattle were examined with three class-specific monoclonal antibodies, IL-A30, IL-A50 and B5/4. In all 47 animals tested, mAb IL-A30 detected a similar percentage of peripheral blood lymphocytes as a mAb that recognizes all immunoglobulin classes. However, in some animals mAbs IL-A50 and B5/4 detected a lower percentage of B cells compared with IL-A30 or the mAb against total Ig. They both reacted with a proportion of the serum IgM from these animals, while IL-A30 reacted with all serum IgM. Therefore, it is probable that mAb-A30 recognizes an IgM isotypic determinant and mAbs IL-A50 and B5/4 recognize different IgM allotypic determinants. Using mAb IL-A30 it was found that the percentage of peripheral blood IgM+ lymphocytes varied widely between healthy cattle (4-31%) but remained constant, with only minor variations, within individual animals.

Animals↗
PubMed1987

The bovine autologous mixed leukocyte reaction: a proliferative response of non-T cells under the control of monocytes.

The culture of bovine monocyte-depleted peripheral blood mononuclear cells (PBM) (responder) with irradiated autologous undepleted PBM (stimulator) resulted in a strong proliferative response, which was called the bovine autologous mixed leukocyte reaction (MLR). A comparative study was made between this autologous MLR and the bovine allogenic MLR, with respect to the inductive requirements and the nature of responding and stimulator cells. In both the autologous and allogenic MLR, the monocyte was responsible for inducing proliferation: low concentrations of purified monocytes (greater than 95% pure) induced strong proliferative responses, while monocyte-depleted PBM (less than 0.2% monocytes) were unable to induce proliferation. Both MLRs were blocked by monoclonal antibodies specific for class II antigens of the major histocompatibility complex. The magnitude of the autologous MLR was regulated by monocytes: unirradiated monocytes induced or suppressed autologous proliferative responses depending on their concentration in the culture. Proliferating cells, identified by quantifying DNA with chromomycin A3, were all within the population of large cells. In the allogenic MLR, 50% of these large cells were T cells, as defined by monoclonal antibodies. In contrast, all of the proliferating cells in the autologous MLR were non-T cells.

Animals↗
PubMed1986

A cell surface antigen associated with Theileria parva lawrencei-infected bovine lymphoid cells.

Attempts to produce monoclonal antibodies specific for a parasite-encoded or induced antigen on the surface of Theileria parva lawrencei-transformed bovine lymphocytes resulted in the identification of the monoclonal antibody J7. This antibody recognizes a membrane glycoprotein on some T.p. lawrencei-infected bovine lymphoid cells but not on any uninfected bovine lymphoid cells. Inoculation of allogeneic recipient cattle with T.p. lawrencei-transformed cells bearing the J7 determinant resulted in transfer of the parasite but not of the J7 epitope to the recipients' own cells. The presence of the J7 determinant could not be correlated with the parasite phenotype nor with the surface phenotype of the infected cells. It is therefore not known whether the J7 epitope is of parasite origin or whether it is a bovine differentiation antigen modified by the presence of the parasite.

Animals↗