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Biomedical subjects

J M Vossen

Publications and source records attributed to J M Vossen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Interferon-gamma-mediated prevention of graft-versus-host disease: development of immune competent and allo-tolerant T cells in chimeric mice.

Recently it was shown that delayed graft-versus-host disease (GVHD) in mice can be completely prevented by repeated injections of interferon-gamma (IFN-gamma). The characteristics of this sustained IFN-gamma-induced chimerism were studied in more detail. First, the potency of IFN-gamma as a modulator of GVHD was tested in a fully H-2 mismatched murine bone marrow transplantation (BMT) model. Donor bone marrow cells (BMC; C57BL/Rij; H-2b) were mixed with increasing numbers of donor spleen cells (SC) and transplanted into lethally irradiated recipients (C3H/Law; H-2k). Secondly, BMC and SC of the IFN-gamma-induced chimeras (C3H/Law; H-2b) were tested on their immunological competence and GVHD inducing capacity. Repeated injections of the host with IFN-gamma were able to prevent GVHD even when up to 10(5) SC were added to the graft; adding higher numbers of SC resulted in a rapid increase in the frequency of lethal GVHD. Donor-derived lymphocytes (H-2b) obtained from chimeric animals were immunocompetent as concluded from Con A stimulation in vitro. Chimeric-derived BMC (H-2b) were mixed with up to 10(7) chimeric SC (H-2b) and transplanted into a new group of lethally irradiated C3H/Law (H-2k) recipients. All transplanted animals survived the latter treatment without any macroscopic signs of histological lesions typical of GVHD. We conclude that IFN-gamma treatment allows the development of mature donor-derived immunocompetent T cells, which are allo-tolerant for the recipient.

Animals↗
PubMed1997

Problems and possible solutions in finding an unrelated bone marrow donor. Results of consecutive searches for 240 Dutch patients.

To evaluate the efficiency of our protocol for finding an HLA matched unrelated bone marrow donor, search results obtained between 1990 and 1995 for 240 Dutch patients were analyzed. The percentage of patients for whom, according to information given by the registries, a fully split-HLA antigen matched donor is available, increased from 24% in 1990 to over 70% in 1995. As a result the percentage of patients transplanted rose from about 24% in 1990-1991 to 44% in 1994-1995. The median time between the start of the search and transplantation was about 6 months. The systematic use of Bone Marrow Donors Worldwide (BMDW) which comprises the HLA groups of all volunteer bone marrow donors in Europe, Israel, South Africa, North America, Canada, India, Australia and New Zealand has been essential in this context. While searching for a suitable donor several problems were encountered such as unavailability of donors (12%) and discordant typing results (8%; range < 1% to > 25%). Thus it is advisable to select several donors for a patient. For 86% of patients with at least one HLA identical donor on the serological level for HLA-A,-B,-DR,-DQ, an HLA-DRB1/3/4/5, and -DQB1 identical donor could be identified. As expected, patients with two frequent haplotypes in strong linkage disequilibrium had the best chance of obtaining an HLA matched donor. Unexpectedly, patients with only one such haplotype had an almost similar chance. It could be calculated that HLA-DR typing of HLA-A,-B identical donors was rarely cost-effective after 1992. Only 12 of the 75 transplanted patients (16%) typeable at DNA level for class II, turned out to be completely matched for HLA-A,-B,-C,-DRB1/3/4/5,-DQB1,-DPB1 and had a negative MLC test. In the group of patients transplanted with a fully matched donor and for whom a CTLp test was performed, only 7% (4/54) of the tests were negative. Search results for patients of non-European origin were dismal, with only four of 26 patients referred being transplanted. In summary, of the 240 patients for whom the Europdonor office searched for a donor, about one-third were transplanted, one-third had a potential donor but did not reach transplantation, while for the remaining one-third of patients no suitable donor could be found.

Adult↗
PubMed1997

Expression of the human immunoglobulin heavy chain VH6 gene element by fetal B lymphocytes.

Fetal B lymphocytes in mice and humans use a limited number of the available VH gene segments. Mouse fetal B cells primarily utilize 3' VH elements, suggesting that the localization of these elements determines their rearrangement frequency. The previously reported non-random usage of human VH genes has been more difficult to explain. In this study the authors analysed the expression of the most proximal 3' human VH element (VH6) using a monoclonal antibody (JE-6). VH6 expression was assessed in various B cell differentiation stages from fetal liver, bone marrow and spleen at 12-20 weeks of gestation. The authors demonstrate that the level of VH6 expression does not exceed a stochastic usage frequency. This suggests that the localization of VH6 does not significantly promote its expression during human fetal life, and that other factors must affect the usage of VH genes during human fetal development.

Antibodies, Monoclonal↗
PubMed1997

Difference in binding of killed and live Streptococcus pneumoniae serotypes by C-reactive protein.

The binding and opsonic properties of C-reactive protein (CRP) for various species of bacteria were investigated. CRP bound more avidly to killed than to live Streptococcus pneumoniae, the binding varying among various serotypes; CRP hardly bound to a number of other bacterial species studied. CRP enhanced complement-dependent phagocytosis of live S. pneumoniae by granulocytes but did not enhance the phagocytosis of live Staphylococcus aureus or group B streptococci. We suppose that CRP may serve as an opsonin for killed bacteria and bacterial debris but is probably not an important opsonin for live bacteria other than S. pneumoniae.

Adult↗
PubMed1996

Identification of an unusual Fc gamma receptor IIIa (CD16) on natural killer cells in a patient with recurrent infections.

We found an unusual fc gamma receptor IIIa (CD16) phenotype on the natural killer (NK) cells of a 3-year-old boy, who suffered from recurrent viral respiratory tract infections since birth. He also had severe clinical problems after Bacille Calmette-Geérin (BCG) vaccination and following Epstein-Barr virus and Varicella Zoster virus infections. His peripheral blood lymphocytes contained a normal percentage and absolute number of CD3-CD7+ cells, which were positively stained with the CD16 monoclonal antibodies (MoAbs) 3G8 and CLBFcRgran1, but did marginally stain with the CD16 MoAb Lau11c/B73.1. Fc gamma RillIb expression on granulocytes appeared to be normal. NK cell function, analyzed in vitro by direct cytotoxicity on K562 target cells and ADCC-activity on P815 target cells, was normal compared with an age-matched healthy control. Sequence analysis of the Fc gamma RIIIA gene, encoding CD16 on NK cells and macrophages, showed a T to A nucleotide substitution at position 230 on both alleles, predicting a leucine (L) to histidine (H) amino acid change position 48 in the first extracellular lg-like domain of Fc gamma RIIIa, which contains the Leu11c/B73.1 epitope. The combined use of CD16 and CD56 MoAbs labeled with the same fluorescent dye, as often applied in routine immunophenotyping procedures, will leave these homozygotes undiagnosed. The pattern of infections in this patient is in agreement with the postulated function of NK cells in the immunological defense against viruses and other intracellular microorganisms. Further analysis of the NK cell function in vitro and follow-up of the clinical course of Fc gamma RIIIA-48H/H homozygotes is required to ascertain whether this genotype is causally related to an NK cell immunodeficiency.

CD56 Antigen↗
PubMed1996

Drug states as modulators of conditioned immobility in a latent discrimination procedure.

Midazolam, amphetamine, and flesinoxan were used in four rat experiments to examine the usefulness of a latent Pavlovian discrimination procedure to assess the discriminative-stimulus, or occasion-setting, properties of drugs. Experiment 1 first assessed the unconditioned effect of each of the drugs on the dependent measure used, which was immobility. Relative to saline, midazolam enhanced immobility, whereas flesinoxan, and especially amphetamine decreased it. In each of the Experiments 2-4, subjects received a limited number of training sessions during which they consistently received a footshock in a distinctive box after a drug but not after saline, or vice versa. Subsequently, non-reinforced test sessions were performed in the drug and saline states in both the conditioning box and a novel box. Relative to the saline state, rats previously shocked under midazolam were less mobile in the conditioning box under midazolam, whereas rats previously not shocked under amphetamine or flesinoxan were more mobile under the drug. The remaining animals did not show differential responding. The response profiles were accounted for in terms of the combined operation of an associative, or occasion-setting, effect and a non-associative effect of the drug-induced states.

Amphetamines↗
PubMed1996

Human T cell repertoire generation in the absence of MHC class II expression results in a circulating CD4+CD8- population with altered physicochemical properties of complementarity-determining region 3.

In this study, we have investigated the impact of deficient MHC class II expression on the use of TCRBV6 and TCRBJ gene elements, and on the pattern of amino acid incorporation exhibited in the N1-D-N2 segments of the third complementarity-determining region (CDR3) of these TCRBV6 rearrangements. To this end, we have analyzed circulating T cells from three, nonrelated MHC class II-deficient (bare lymphocyte syndrome (BLS)) patients and three MHC class II-expressing family members. The patients and healthy controls exhibited similar, nonrandom usage profiles of TCRBV6 and TCRBJ gene elements in both the CD4+CD8- and the CD4-CD8+ subsets of peripheral blood T cells. No statistically significant differences between patients and controls were detected in the length of CDR3, or in the amount of non-germline modification at the sites of recombination. However, detailed analysis of the TCRBV6 rearrangements derived from the CD4+CD8- subsets from the BLS patients revealed patterns of amino acid incorporation into the N1-D-N2 region of CDR3 that resulted in altered charge and hydropathicity properties of the presumed Ag binding site. In this way, we have been able to demonstrate that human T cell repertoire development in the absence of MHC class II expression results in a circulating CD4+CD8- T cell population bearing TCRs with altered CDR3 profiles. Such altered profiles are likely to be a direct reflection of the lack of MHC class II-mediated selection processes in these BLS patients.

Amino Acid Sequence↗
PubMed1996

The origin of IgG production and homogeneous IgG components after allogeneic bone marrow transplantation.

Pediatric recipients (n = 25) of an allogeneic bone marrow (BM) graft were selected on the basis of informative IgG allotype (Gm) differences between the BM donor and the recipient. To investigate the kinetics of the appearance of IgG of donor origin and the disappearance of IgG of recipient origin, G1m and G2m allotype levels were quantified in sera obtained at regular intervals between 3 months and 5 years after BM transplantation (BMT). For this quantification, a dot immunobinding assay (DIBA) has been developed. In 19 of 22 informative recipients, the Gm allotype distribution had reached the range of values expected on the basis of the Gm phenotype of the donor within 6 months after BMT. Remarkably, IgG of recipient origin persisted in 15 of 18 informative recipients until last follow up, ie, for several years after BMT. In addition to the origin of total IgG production, the origin of homogeneous IgG components (H-IgG) appearing after BMT was investigated. H-IgG of donor origin could be detected as early as 3 weeks after BMT, but also H-IgG of recipient origin were present in 8 of 13 informative recipients for a period of up to 1 year after BMT. We conclude that host-type IgG-producing cells were not eradicated by the (myeloablative) conditioning regimen and persisted in a high number of graft recipients. It is our hypothesis that lack of graft-versus-host disease (GVHD) in the majority of these recipients results in the persistence of IgG-producing cells of host origin. These observations may be relevant for the evaluation of patients who received allogeneic BMT for the treatment of multiple myeloma.

Anemia, Aplastic↗
PubMed1996

Final height and hormonal function after bone marrow transplantation in children.

AIM: To analyze final height and hormonal function in long-term survivors of bone marrow transplantation (BMT). PATIENTS: Group 1 consisted of 16 patients (10 boys) with a hematologic malignancy, mostly leukemia, conditioned for BMT with total body irradiation (TBI), 7.5 to 12 Gy, and cyclophosphamide. Group 2 consisted of 14 patients (9 boys) with severe aplastic anemia, conditioned with chemotherapy only. RESULTS: In group 1, patients achieved a reduced final height after BMT. The difference between the height standard deviation score (SDS) at BMT and the height SDS at final height was -1.96 (0.82) SDS in boys and -0.92 (0.71) SDS in girls (p = 0.0001, and p = 0.02 respectively). Final height was also lower than target height (boys, p = 0.01; girls, p = 0.03). Prepubertal growth in the first 3 years after BMT was normal but pubertal height gain was decreased. The patients in group 2 achieved normal height. Thyroid function and adrenal function were normal in all patients, and no growth hormone deficiency was detected. Serum follicle-stimulating hormone values after BMT were increased in all group 1 patients, with return to normal in two patients. Serum luteinizing hormone values were increased in all group 1 girls, with recovery in one girl. Normal serum luteinizing hormone values and spontaneous puberty were found in all group 1 boys. In group 2, disturbances in gonadotropins were seen only in three boys and two girls. CONCLUSION: In patients treated in childhood with BMT after chemotherapy and TBI with 7.5 Gy or more, final height is compromised because of blunted growth in puberty. Patients who had not received TBI suffered no height loss. In the majority of patients, the combination of chemotherapy and TBI also resulted in irreversible disturbances of gonadal function.

Adolescent↗
PubMed1996

Follow-up of leucocyte and reticulocyte counts for the prediction of early graft failure after non-HLA-identical BMT in children.

Allogeneic BMT using a non-genotypically HLA-identical donor may be curative for children suffering from lethal haematological diseases, who lack a genotypically HLA-identical donor. Unfortunately, graft failures are often seen, especially after T cell depletion of the graft. We studied whether untimely decreased counts of leucocytes and reticulocytes in peripheral blood might predict graft failure at an early stage. Fifty-five recipients of a non-genotypically HLA-identical BM graft were included in the study; data from these children were compared with those of 77 recipients of a genotypically HLA-identical BM graft. Time-related reference values of peripheral blood leucocyte and reticulocyte counts were established in graft recipients with proven donor-origin recovery after BMT. Graft failure after nonHLA-identical BMT was observed in 16 out of 55 children (29%) and after HLA-identical BMT in one out of 77 (1.3%). With respect to early graft failure, the predictive value of granulocyte numbers falling below the lower limit of the reference values and a rapid decline of reticulocyte numbers after their appearance in peripheral blood was 100% (95% confidence intervals of 83-100% and of 80-100%, respectively). Early immunosuppressive intervention was applied in six patients and was successful in three of them.

Adolescent↗
PubMed1996

Search for the antigen-specificity of homogeneous IgG components (H-IgG) after allogeneic bone marrow transplantation.

After allogeneic BMT, transient homogeneous Ig components (H-Ig) can be detected in the sera of most graft recipients. So far, data on the antigen-specificity and therefore the function of these H-Ig are not available. Such information may be important for our understanding of the underlying mechanisms that are responsible for these excessive clonal B cell expansions, and it may help to delineate the functional antibody repertoire after BMT. In the present study, sera of 98 paediatric BM graft recipients were investigated for the potential presence of H-Ig of IgG isotype (H-IgG) with specificity towards a panel of antigens, including vaccine and herpes virus antigens, auto-antigens and allo-antigens. The vast majority of H-IgG in sera of BM graft recipients were unreactive when tested for this panel of antigens. However, in four cases, antigen-specificity of H-IgG to tetanus toxoid could be demonstrated after vaccination with that antigen. An explanation for the negative findings may be either that a restricted antibody production had been elicited by other non-tested antigens, eg substances of colonizing and translocating bacteria or of food antigens, or that the H-IgG components may have anti-idiotype or anti-'self' specificity.

Adult↗
PubMed1996

Risk factors for developing EBV-related B cell lymphoproliferative disorders (BLPD) after non-HLA-identical BMT in children.

B cell lymphoproliferative disorders (BLPD) are relatively frequent after genotypically non-HLA-identical BMT. We performed univariate analysis to study which BMT-related variables were associated with an increased risk of developing BLPD. Sixty-five recipients of other than genotypically HLA-identical BM grafts were included in the study. Seventy-seven recipients of genotypically HLA-identical BM grafts served as a comparison group. BLPD occurred in nine of 65 children after non-HLA-identical BMT (14%) and in none of the 77 children after HLA-identical BMT (0%). In all cases, BLPD was proven to be EBV-related. Our data suggest that the combined use of Campath 1G and anti-LFA1 was associated with an increased risk of developing BLPD, particularly children who had received a T cell-depleted BM graft, using albumen density gradient sedimentation followed by E-rosetting, and who were conditioned with Ara-C, CY and TBL. In addition, T cell numbers below 50/microliters at 1 month and below 100/microliters at 2 months after BMT, respectively, were associated with an increased risk of developing BLPD. Longitudinal determination of T cell numbers after non-HLA-identical BMT is a simple method for identifying patients at risk of developing BLPD. In addition to monitoring levels of circulating EBV-infected lymphocytes, monitoring T cell numbers may allow early intervention to prevent progression of BLPD.

Adolescent↗
PubMed1996

Bone marrow transplant indications for childhood leukemias: achieving a consensus. The EBMT Pediatric Diseases Working Party.

During the "2nd International Course on Bone Marrow Transplantation in Children" a multiple choice questionnaire on bone marrow transplant indications for children with acute leukemias was distributed with the aim of achieving a consensus. The answers obtained from the twenty representatives of fourteen European countries during the meeting were analyzed and assigned to one of the following groups: I. definitive indication: when more than 75% participants were in favour; II. acceptable indication: when 50% to 74% participants were in favour; III. requires further investigation: when 25% to 49% participants were in favour; IV. no indication: when less than 24% participants were in favour. In acute lymphoblastic leukemia the following circumstances were considered a definitive indication for allogeneic bone marrow transplant (BMT) from a matched sibling donor (MSD): infancy, "high risk" (HR) patients in 1st complete remission (CR1); CR2 patients after an early bone marrow relapse (defined as a relapse occurring up to six months after stopping therapy). Patients experiencing an early meningeal relapse and CR2 patients after a late relapse (defined as a relapse occurring later than six months after stopping therapy) were considered an acceptable indication. Further investigation was required in order to better define the role of BMT for patients experiencing an early isolated testicular relapse. If a MSD is not available, HR patients in CR1 and CR2 patients, after an early bone marrow relapse, were considered a definite indication for a matched unrelated donor (MUD). This latter group was considered an acceptable indication for a haploidentical BMT if a MUD was not available. Further investigation was required to better define the role of autologous bone marrow transplant (ABMT) for patients experiencing an early extramedullary relapse and for HR patients in CR1 all of whom lacked MSD's. In acute myeloblastic leukemia (AML), CR2 patients were considered a definitive indication and CR1 patients were considered an acceptable indication for BMT from a MSD. CR2 patients were considered a definitive indication for ABMT and CR1 patients an acceptable indication in cases lacking a MSD. AML was not considered an indication for MUD BMT.

Bone Marrow Transplantation↗
PubMed1995

Sleep deprivation and spike-wave discharges in epileptic rats.

The effects of sleep deprivation were studied on the occurrence of spike-wave discharges in the electroencephalogram of rats of the epileptic WAG/Rij strain, a model for absence epilepsy. This was done before, during and after a period of 12 hours of near total sleep deprivation. A substantial increase in the number of spike-wave discharges was found during the first 4 hours of the deprivation period, whereas in the following deprivation hours epileptic activity returned to baseline values. Immediately after termination of deprivation, a decrease in the number of spike-wave discharges parallelled a rebound of rapid eye movement (REM) sleep and deep non-REM sleep. An initial increase in epileptic activity has also been reported during sleep deprivation of humans. This initial increase as well as the epileptogenic effects during the course of the sleep deprivation and during the recovery period after sleep deprivation can be interpreted in terms of changes in sleep-wake states. Although the epilepsy-provoking mechanisms are not yet understood, an explanation is suggested based on changes of transitions between sleep-wake states and shifts in level of synchronization.

Animals↗
PubMed1995

Case-control analysis of allogeneic bone marrow transplantation versus maintenance chemotherapy for relapsed ALL in children.

In a retrospective study, the results of maintenance chemotherapy and allogeneic bone marrow transplantation (BMT) for children who reached a second complete remission (CR2) of their acute lymphoblastic leukemia (ALL) were compared. Case-control analysis was performed comparing 25 allogeneic transplant patients (cases) with 97 patients treated with maintenance chemotherapy (controls), who were matched for site of relapse, duration of CR1 and leukemia-free interval from onset of CR2. Until the first relapse, the children were treated according to standard protocols. The majority of patients suffered from a bone marrow relapse, mostly occurring more than 24 months after the onset of CR1. Remission reinduction treatment was heterogeneous. Patients treated with allogeneic BMT received high-dose chemotherapy and total body irradiation prior to BMT. Maintenance chemotherapy in controls was given for approximately 2 years. Following BMT, relapse rate was lower but the treatment-related mortality was higher compared with maintenance chemotherapy, resulting in leukemia-free survival rates at 4 years of 44% and 24%, respectively (not significant, NS). Case-control analysis of leukemia-free survival showed a hazard ratio of 0.756 in favor of BMT compared with chemotherapy (NS). If bone marrow relapses and central nervous system relapses were analyzed separately, a tendency to better leukemia-free survival was present after BMT compared with maintenance chemotherapy for patients with a relapse in the central nervous system, but for an isolated bone marrow relapse, no differences in leukemia-free survival were seen between the two groups of patients.

Antineoplastic Agents↗