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J Naessens

Publications and source records attributed to J Naessens.

At least 19 recordsLinked to original sources
PubMed1998

Effective in vivo depletion of T cell subpopulations and loss of memory cells in cattle using mouse monoclonal antibodies.

Conditions were established to obtain depletion of T lymphocyte subsets in lymphoid tissues of calves by injection of mouse monoclonal antibodies to T cell antigens. Adverse reactions were avoided by injecting small quantities of antibody, until target cells had disappeared from blood. Two different mechanisms appeared to be responsible for elimination of the target cells. Rapid depletion of T cells was associated with complement-binding antibody isotypes (IgG2a, IgM), suggesting a complement-mediated mechanism. Clearance of T cells after several days was observed with a non complement-binding isotype (IgG1), suggesting phagocytosis or induction of apoptosis as possible mechanisms. Clearance of the cells in peripheral blood and spleen was obtained with 10-20 mg of anti-CD4 or anti-CD8, but almost ten times as much was needed to obtain depletion of the cells in lymph nodes and Peyer's patches. Depletion lasted for 12 days for CD4 T cells and 3 weeks for CD8 T cells. Successful and lasting depletion (at least 2 weeks) was also obtained with other T cell reagents, such as anti-CD2 and anti-WC1 (gamma/delta T cells). Although B lymphocytes could be removed by a complement-binding antibody, complete depletion of these cells only lasted for a few hours, probably because B cells regenerate faster than T cells. T cell function was severely inhibited when CD4+ T cells were depleted. Stimulation of T cells with foot and mouth disease viral antigen (FMDV) in vaccinated calves was non-existent after depletion. Even 2 months after restoration of normal CD4 T cell levels in blood, activity to FMDV was low. This suggested that the depleted T cells were replaced by naive cells.

Animals↗
PubMed1998

Proteolytic cleavage of surface proteins enhances susceptibility of lymphocytes to invasion by Theileria parva sporozoites.

A flow cytometric method using anti-parasite antibodies was developed to measure binding of Theileria parva sporozoites to the target bovine lymphocyte membrane. Parasite-host cell interactions could be inhibited by monoclonal antibodies to bovine MHC class I and partially by one of two antibodies to BoCD45R. Proteolysis of the lymphocyte surface removed CD45R but not MHC class I determinants, and enhanced sporozoite binding. These observations support the hypothesis that CD45R and CD45R antibodies may nonspecifically prevent close approximation between sporozoites and lymphocytes. Interestingly, under normal conditions, sporozoites of T. parva did not attach to lymphocytes from goats, but did so when the cells were treated with the protease, suggesting that receptor(s) for T. parva sporozoites might be present on caprine cells but are not easily accessible. These and other results indicate that proteases may be involved in binding and entry of T. parva sporozoites. Electron microscopy revealed that the process of binding and entry of sporozoites into protease-treated goat lymphocytes was very similar to that of the bovine cells. However, schizonts did not develop and lymphocyte proliferation was not induced, indicating that cell entry by sporozoites and cellular transformation are separate processes.

Animals↗
PubMed1998

B-1-like cells exist in sheep. Characterization of their phenotype and behaviour.

Two populations of B lymphocytes, B-1 (CD5+ and/or CD11b+) and B-2 (CD5- and CD11b-) cells have been described. In mice, which is the species of reference for B-1 and B-2 cell studies, these two subsets present different developmental schemes, phenotypes, antibody repertoires, localization and behaviours. Interestingly, in sheep, B cells rearrange their immunoglobulin (Ig) loci around the neonatal period, similarly to murine B-1 cells. However, the phenotype of the sheep B cells has not been characterized with regards to their developmental pathway. In this report, we show that two sheep B-cell subsets can be distinguished on the basis of CD11b expression. Relative to CD11b- B cells, the CD11b+ B cells frequently co-express CD5, CD11c, higher levels of surface IgM (sIgM), show larger cell size and higher cell-cycling activity, and thus present a B-1-like phenotype. However, unlike murine B-1 cells, sheep B-1 like cells mainly localize in blood, display a higher propensity to spontaneous apoptosis relative to B-2-like cells, and proliferate after sIgM stimulation. Our data show that despite neonatal immunoglobulin loci rearrangements, sheep B cells do not all express a B-1-like phenotype. However, B-1-and B-2-like cells co-exist and present phenotypic and behavioural specificities. Nevertheless, sheep B-1-and B-2-like cells differ from the murine B-1 and B-2 cells in their cell behaviour. These subsets can thus not be considered as true homologues among species.

Animals↗
PubMed1997

CD5+ B lymphocytes are the main source of antibodies reactive with non-parasite antigens in Trypanosoma congolense-infected cattle.

Mice infected with African trypanosomes produce exceptionally large amounts of serum IgM, a major part of which binds to non-trypanosome antigens such as trinitrophenol and single-strand DNA. In this paper, we describe that in cattle infected with Trypanosoma congolense and T. vivax, similar antibodies are found, although they bind mainly to protein antigens, such as beta-galactosidase, ovalbumin and ferritin. The parasite non-specific IgM antibodies appear around the same time as the parasite-specific antibodies, but their origin and function are not clear. We tested the hypothesis that CD5+ B cells (or B-1 cells), which increase during trypanosome infections in cattle, are responsible for production of antibodies to non-trypanosome antigens. Splenic CD5+ and CD5- B cells from infected cattle were sorted and tested in a single cell blot assay. The numbers of immunoglobulin-secreting cells were similar in both B-cell populations. However, antibodies with reactivity for non-trypanosome antigens were significantly more prevalent in the CD5+ B-cell fraction and were exclusively IgM. The preference for production of these antibodies by CD5+ B cells and the expansion of this subpopulation during infections in cattle, strongly suggest that CD5+ B cells are the main source of trypanosome non-specific antibodies. We propose that these antibodies are natural, polyreactive antibodies that are predominantly secreted by CD5+ B cells. Since B-1 cells are up-regulated in many states of immune insufficiency, the immunosuppression associated with trypanosome infections may be responsible for the increase of this subset and the concomitant increase in trypanosome non-specific antibodies.

Animals↗
PubMed1997

Surface Ig on B lymphocytes from cattle and sheep.

IgD, first demonstrated in humans, has been unequivocally shown to exist in primates and rodents. In addition to IgM a second unique membrane isotype, generally considered to be IgD, has been demonstrated in a number of other species, including dogs and chickens. Because of its assumed widespread presence, it is widely accepted that IgD is phylogenetically conserved and therefore functionally important in B cell maturation. In the present paper, we could not demonstrate IgD on bovine B cells derived from peripheral blood, lymph nodes, spleen and fetal spleen by precipitation with anti-light chain antibodies. This lack of detectable IgD was confirmed in peripheral blood B cells of sheep, and raises questions on the requirement for IgD in cell differentiation and Ig secretion. At present it is not clear whether cattle (and sheep) are an exception in this context. Reports of the presence of IgD in different species are largely based on the assumption that non-IgM surface Ig is most likely IgD. Our data question this extrapolation and stress the need for further isotype characterization of the surface Ig in different species. Lack of surface IgD has been observed in human and mouse B-1 cells, most of which express the surface marker CD5. The possibility that all bovine B cells belong to the B-1 lineage is discussed.

Animals↗
PubMed1996

Characterisation of bovine transferrin receptor on normal activated and Theileria parva-transformed lymphocytes by a new monoclonal antibody.

A murine IgM monoclonal antibody (mAb), IL-A77, has been generated that recognises the bovine transferrin receptor (TfR) and will be a useful tool to measure the activation state of bovine lymphocytes and macrophages. The antigen is detected on immature erythroid cells and proliferating lymphocytes. It is undetectable on resting lymphocytes, but appears within 24 h after stimulation with concanavalin A (ConA) or pokeweed mitogen (PWM). Immune precipitations of lysates of both labeled activated lymphocytes and bone marrow erythroid cells showed that, similar to human TfR, the bovine receptor is a disulfide-bonded dimer of two identical chains of M(r) 97,000. A similar 97,000 M(r) protein was eluted from a column containing immobilised bovine transferrin (Tf) using conditions known to elute the human TfR, and this protein was recognised by mAb IL-A77, proving that it detected bovine TfR. Although the mAb inhibited binding of transferrin to its receptor, it did not block proliferation of Theileria parva-transformed or ConA-stimulated lymphocytes. When cells were metabolically labeled with 35S-methionine, a second 90,000-M(r) TfR band was detected in Theileria parva-transformed cells, but not in stimulated lymphocytes. This form of the TfR was not expressed on the cell surface. It may be an.

Animals↗
PubMed1996

Ruminant cluster CD71.

Two monoclonal antibodies (mAbs) belong to this cluster: IL-A77 and IL-A165. They clustered closely in PC16c. The first mAb, an IgM, was raised against bovine activated B cells, the second was an IgG1 raised against bovine bone marrow cells.

Animals↗
PubMed1996

Analysis of monoclonal antibodies specific for the gamma delta TcR.

gamma delta T cells in ruminants can be subdivided in two or more subpopulations on the basis of the expression of surface antigen WC1, which can exist in different isoforms. In this study, 18 monoclonal antibodies (mAbs) submitted to the Third International Workshop that were predicted to react with gamma delta TcR molecules were analysed and expression of their antigens was investigated on the different gamma delta T cell subpopulations. A set of control mAbs positive for TcR1 (86D), BoCD3 (MM1A), WC1 (B7A1, BAQ4A, CACTB32A, and BAQ89A) was included for comparative studies. Previous investigations demonstrated eight of the mAbs immunoprecipitated peptides with apparent M(r)s of 37 and/or 47 kDa, indicating they recognized determinants on the T cell receptor, TcR1. Two color flow cytometric analyses in the present study demonstrated the mAbs formed three groups; group 1, a set of mAbs that recognize TcR1 determinants expressed on all gamma delta T cells and groups 2 and 3, sets of mAbs that recognize TcR1 determinants on some gamma delta T cells: TcR1-N6 and TcR1-N7 respectively. mAbs from the latter groups define families of TcR1 molecules that express either one or both of the determinants. These antigenically distinct forms of TcR1 are expressed in equal proportion on the two gamma delta T cell populations that express one of the mutually exclusive isoforms of WC1, WC1-N3 and WC1-N4. The data indicate usage of the mAb-defined families of the gamma delta TcR is primarily restricted to the WC1+ subpopulation of gamma delta T cells. However, a small subpopulation of CD2+, WC1- gamma delta T cells expresses a form of TcR1 positive for the determinant TcR1-N6.

Animals↗
PubMed1996

Analysis of monoclonal antibodies reactive with molecules upregulated or expressed only on activated lymphocytes.

Monoclonal antibodies potentially specific for antigens expressed or upregulated on activated leukocytes were selected for further analysis from the panel submitted to the third international workshop on ruminant leukocyte antigens. The kinetics of expression of these activation antigens on resting peripheral mononuclear cells (PBMC) and PBMC stimulated with concanavalin A or staphylococcal superantigen SECI for 4, 24 or 96 h were compared, as well as their appearance on various subsets of cells. For some of them, a molecular mass could be determined after immunoprecipitation from radio-labeled, lectin-stimulated cells. Based on the results from the clustering, kinetic studies and biochemical data, evidence was gathered for assigning two additional mAbs to cluster BoCD25 (IL-2 receptor) and two mAbs to cluster BoCD71 (transferrin receptor). Four mAbs recognized an early activation antigen predominantly expressed on gamma delta T cells in short-term cultures. A number of other activation antigens were further characterized.

Animals↗
PubMed1996

Biochemical analysis of preliminary clusters in the non-lineage panel.

After the preliminary clustering of the whole workshop panel using flowcytometry data, we selected those clusters that were composed of mAbs that bound a broad range of cells. To obtain evidence that mAbs in each of these preliminary clusters detected the same antigen, they were tested for their capacity to compete with each other for binding to a target cell and the molecular weights of their antigens were estimated after immunoprecipitation. Most preliminary clusters in the non-lineage panel contained control mAbs that had been characterised in one of the previous workshops, and this study therefore increased the number of mAbs available to each of these non-lineage antigens. One new interesting cluster, BoWC14, was described which defined an antigen on myeloid cells and a subpopulation of CD4, CD8 and WC1 T lymphocytes (BT3/8.12 and IL-A155). An additional cluster, which did not fit into any other panel, contained mAbs specific for an antigen restricted to the erythroid lineage and received the nomenclature BoWC15 (ANA8, IL-A135, IL-A137, IL-A138 and IL-A160).

Animals↗
PubMed1996

The role of anti-variable surface glycoprotein antibody responses in bovine trypanotolerance.

It has been reported that some breeds of cattle such as the N'Dama mount a more effective antibody response to the variable surface glycoprotein coat of trypanosomes and that this may contribute to their ability to control the infection. Thus we have investigated antibody responses to surface exposed epitopes of the variable surface glycoprotein in Trypanosoma congolense-infected N'Dama (trypanotolerant) and Boran (susceptible) cattle. Similar titres and isotypes were found in both N'Damas and Borans indicating that trypanotolerance is not associated with superior antibody-mediated destruction of trypanosomes. However, significant differences in antibody responses to cryptic VSG epitopes and non-trypanosome antigens were identified. Trypanosusceptible Boran cattle had low IgG1 responses to cryptic epitopes but high IgM responses to non-trypanosome antigens such as beta-galactosidase. In contrast the N'Dama cattle had significantly higher IgG1 responses to cryptic VSG epitopes and negligible responses to beta-galactosidase. These results indicate differences in the induction of anti-trypanosome immune responses between trypanotolerant and susceptible cattle infected with T. congolense.

Animals↗
PubMed1995

Are CD8 T cells involved in control of African trypanosomiasis in a natural host environment?

Murine models have suggested that CD8 T cells might play a major parasite-promoting role in African trypanosomiasis. To assess the role of these cells in a natural host environment, we have depleted CD8 cells from Boran cattle in vivo and subsequently infected these animals with Trypanosoma congolense by tsetse fly challenge. Following administration of a mouse monoclonal anti-bovine CD8 antibody, we have been able to achieve a depletion of more than 99.9% in peripheral blood, spleen, prescapular lymph nodes, prefemoral lymph nodes, mesenteric lymph nodes and Peyer's patches. Depletion could be maintained over a 4-5-week infection period. Despite the almost total absence of CD8 cells, no effect whatsoever was observed on parasitemia. In addition, anemia, which is the main factor determining the mean survival time in cattle was not affected by the CD8 depletion.

Animals↗
PubMed1995

Renal endarterectomy vs. bypass for combined aortic and renal reconstruction: is there a difference in clinical outcome?

Are there differences in the patient characteristics and clinical outcome for transaortic renal endarterectomy vs. bypass grafting when either technique is combined with infrarenal aortic replacement for occlusive or aneurysmal disease? Two common perceptions persist: (1) combined aortic and renal procedures have a high risk and (2) bypass is easier and safer than endarterectomy. To address these controversies we compared 52 consecutive patients undergoing concomitant aortic and renal reconstruction between 1987 and 1991: 26 with bypass and 26 with endarterectomy. Bypass patients were older (70 vs. 64 years, p = 0.001), had more extensive plaque extending into the distal renal artery and more severe baseline azotemia (creatinine = 2.6 vs 1.7 mg/dl, p = 0.01), more clinically evident coronary heart disease (89% vs. 56%, p = 0.001), and a greater need for nephrectomy of a small nonfunctional pressor kidney (23% vs. 0%) than endarterectomy patients. In contrast, endarterectomy patients more commonly required aortic replacement for occlusive disease than for an aortic aneurysm (endarterectomy: 65% vs. 35%; bypass: 19% vs 81%, p = 0.002) and tended to require more intraoperative technical revisions (12% vs. 4%) than bypass patients. Both groups, however, experienced no operative mortality, had similar cardiorespiratory morbidity, and achieved equal improvement in hypertension (69% vs. 65%). Bypass patients, who already had more severe preoperative azotemia than endarterectomy patients, showed less improvement in the creatinine level (Cr = 2.1 vs. 1.4 mg/dl, p = 0.01) and had greater need for late dialysis (30% vs. 4%, p = 0.01). Only one patient on dialysis had graft occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Infected lower extremity extra-anatomic bypass grafts: management of a serious complication in high-risk patients.

To determine optimal management and outcome of infected extra-anatomic bypass grafts (EABG), we reviewed 28 patients (19 men and 9 women; mean age 70 years) treated over a 13-year period. Mean follow-up was 42 months. There were 16 axillofemoral (AF), 10 femorofemoral (FF), and two axillopopliteal (AP) grafts. Risk factors included previous prosthetic graft infection in 13 patients, enterocutaneous fistula in two, and mycotic aortic aneurysm in one. Initial management involved complete graft excision in 12 patients, partial graft excision in 10, and nonresectional therapy in six. Failure of nonresectional therapy and partial excision in three patients each required further operative intervention with graft excision. Reconstruction in patients eventually requiring graft excision (n = 25) entailed placement of a new prosthetic AF or AP graft in eight, an autogenous FF graft in five, combined prosthetic AF and autogenous FF bypass in two, autogenous iliofemoral bypass in one, obturator bypass in one, or no reconstruction in eight. Four autogenous FF reconstructions thrombosed immediately postoperatively, and three prosthetic reconstructions became infected. The mortality rate was 18% (FF = 20%, AF = 19%, AP = 0%). The amputation rate was 25% (AP = 100%, AF = 25%, FF = 10%) and was higher without arterial reconstruction (56% vs. 12%, p = 0.02). Two patients required hemipelvectomies and one had bilateral hip disarticulation. We conclude that EABG infections can be successfully treated but carry significant morbidity and mortality. Optimal management includes EABG resection and prompt revascularization, bearing in mind the risk of early thrombosis in autogenous grafts and reinfection in prosthetic grafts.

Aged↗
PubMed1995

Characterization of monoclonal antibodies to the alpha IIb beta 3 integrin on bovine platelets.

A set of monoclonal antibodies (MoAbs) to leucocyte antigens is an essential tool to identify different cell types and functional membrane molecules involved in immune responses. Since no MoAbs existed to bovine integrins, except against the beta 2 subfamily, we generated MoAbs to beta 3 integrin after the immunization of mice with bovine platelets. Two MoAbs, IL-A164 (IgG2a) and IL-A166 (IgG1), were selected that reacted specifically with bovine platelets and detected the same membrane molecule. The antigen was a heterodimer of two polypeptide chains of 122 kDa and 95 kDa as resolved by SDS-PAGE under reducing conditions. Although the Mr of the smaller subunit is identical to that of beta 2 integrin, preabsorption with an antibody to beta 2 (or CD18) did not remove the bovine antigen. Comparing the molecular masses of the two subunits in reduced and non-reduced forms showed a pattern that was similar to that of human GPIIb/IIIa (also called alpha IIb beta 3 or CD41a). Reduction of the bovine molecule increased the apparent Mr of the light chain from 76 kDa to 95 kDa, while the heavy subunit changed from 136 kDa to 122 kDa. As with human GPIIb, the decrease in Mr of the alpha-subunit is probably a result of a small disulphide-linked polypeptide, although no additional evidence for this was detected for the bovine integrin. Sequencing of the N-terminal amino acids of both bovine polypeptides showed identity of the bovine integrin with human GPIIb/IIIa.

Amino Acid Sequence↗