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Biomedical subjects

O Lantz

Publications and source records attributed to O Lantz.

At least 55 records · Page 3Linked to original sources
PubMed1992

Allogenic recognition in 1992.

Many new data have been obtained in the last 4 years concerning the structure and functions of major histocompatibility complex (MHC) molecules. Structural data are summarized and the functions of MHC molecules in the presentation of peptides to T cells are described. The high selectivity of peptides binding to MHC molecules is discussed. The negative and positive selection of T cells in the thymus is described and the notion of repertoire introduced. The consequences of these new data on the understanding of H2 restriction and alloreactivity are described. The four potential types of alloreactivity are defined: i) house keeping gene (HKG) peptides bound to allogenic MHC molecules; ii) allogenic peptides (derived from allogenic MHC molecules) bound to allogenic MHC molecules; iii) empty allogenic MHC molecules; iv) allogenic peptides bound to autologous MHC molecules. In fact, the allogenic response is mostly directed toward HKG peptides bound to the allogenic MHC molecules of the graft cells (type 1). The potential role of type four alloreactivity in rejection is discussed.

Humans↗
PubMed1992

Evidence that antihuman tumor necrosis factor monoclonal antibody prevents OKT3-induced acute syndrome.

We have used an antihuman tumor necrosis factor monoclonal antibody, CB006 (murine IgG1), to prevent the OKT3-induced acute clinical syndrome. This syndrome is due to the massive, although transient release in the circulation of various cytokines (TNF, interferon gamma, interleukin 2, interleukin 6) and represents one important side effect linked to in vivo use of OKT3. Fourteen kidney allograft recipients undergoing prophylactic OKT3 therapy were treated with CB006 in a single i.v. injection of either 0.4 mg/kg (group I, 7 patients) or 2 mg/kg (group II, 7 patients), 1 hr before the first OKT3 administration. Nineteen consecutive patients formed a historical control group. None of the CB006-pretreated patients showed any of the common, severe OKT3-associated symptoms (hypotension, respiratory distress, or neurotoxicity), which were observed in 10% of the historical controls. In addition, CB006-treated patients showed a lower frequency of pyrexia (> or = 39 degrees C) and gastrointestinal symptoms. None of the CB006-treated patients presented severe vomiting or diarrhea, defined as repeated episodes inducing significant fluid and electrolyte loss. Two out of the 7 patients in group I and group II had mild transitory diarrhea. Mild single vomiting episodes occurred in 2 group I patients and 3 group II patients. At variance in all controls, gastrointestinal symptoms were long lasting and associated with major prostration due to electrolyte and fluid loss. Importantly, CB006-treated patients who presented mild symptoms had detectable bioactive circulating TNF, showing incomplete inactivation of OKT3-induced TNF by CB006. CB006 was perfectly well tolerated, did not induce xenosensitization, and did not affect the biological or clinical effectiveness of OKT3.

Acute Disease↗
PubMed1992

Anti-HLA antibodies depletion on protein A-sepharose columns in hyperimmunized patients awaiting renal transplantation.

To reduce anti-HLA immunization, 15 patients waiting for a renal graft received the following treatment: 5 to 7 immunoadsorption sessions on protein A-Sepharose columns, immunosuppressive drugs (corticosteroids 1 mg/kg (bw/day+cyclophosphamide 2 mg/kg bw/day) and iv polyclonal immunoglobulins. Before this treatment, panel-reactive antibodies ranged from 65 to 100% and antibody titers varied from 1/8 to 1/128. In all patients, antibody, titers were decreased. However, antibody resynthesis was incompletely blocked by this protocol. Eight out of 12 grafted patients had a functional kidney transplant 3 months to 3 years post-grafting. There early kidney failures occurred in the subgroup of 5 patients who had had historical positive cross matches prior to treatment. This treatment did not seem to increase the frequency of infectious complications before or after grafting.

Adult↗
PubMed1991

[Acute clinical syndrome associated with OKT3 administration. Prevention by single injection of an anti-human TNF monoclonal antibody].

This study analyzed the capacity of an anti-human tumour necrosis factor (TNF) monoclonal antibody, CB006 (murine IgG1, Celltech), to prevent the OKT3-induced acute clinical syndrome. Fourteen renal allograft recipients undergoing prophylactic OKT3 therapy were included. CB006 was administered as a single i.v. injection, 0.4 mg/kg (Group I, 7 patients) and 2 mg/kg (Group II, 7 patients), one hour prior to the first OKT3 administration. Nineteen consecutive patients that were part of a randomized multicenter trial constituted the historical control group. In all patients CB006 was perfectly well tolerated and significantly decreased the frequency of the common OKT3-associated acute symptoms. None of the CB006 pretreated patients showed severe life threatening symptoms (hypotension, respiratory distress or neurotoxicity), observed in 10 per cent of historical controls. At variance with controls, in CB006 treated patients gastrointestinal symptoms (vomiting, diarrhea) and pyrexia (body temperature greater than or equal to 39 degrees C) appeared in low frequency, were mild and short lasting, never promoting major prostration of the patients due to electrolytes and fluid loss. Importantly, the presence in some patients of these mild symptoms, correlated with detectable bioactive TNF in the circulation thus reflecting incomplete blockade by CB006 of OKT3-induced TNF. CB006 pharmacokinetics data further stressed the need for adequate dosage adaptation. CB006 did not affect the biological or clinical effectiveness of OKT3. None of the patients showed evidence of anti-CB006 xeno-sensitization.

Antibodies, Monoclonal↗
PubMed1991

[Treatment with Lo-Tact-1, a monoclonal antibody to the interleukin-2 receptor, in kidney transplantation].

From May to August 1989 15 cadaver-donor renal transplant recipients were treated for 14 days with LO-Tact-1 (10 mg i.v. per day) in combination with cyclosporin (8 mg/kg/day from day-1), low-dose steroids (1/2 mg/kg/day from day 1, then reduced to 0.25 mg/kg at day 26 and 10 mg/day at day 45), and azathioprine (1 mg/kg/day) started at day 45. LO-Tact-1 is a rat monoclonal antibody which is directed to the interleukin-2 receptor. The control group consisted of 20 patients receiving cyclosporin, high-dose steroids (2 mg/day at day 1) and a 14-day course of polyclonal horse antilymphocyte globulins (ALG). Seven patients experienced 9 rejections during the first 3 months post-transplant between day 10 and day 67 (mean 0.6 per patient), comparable to the incidence of rejections in the control group: 8 rejections in 7 patients (mean 0.4 per patient). All rejections were reversed by steroid boluses and ATG. To date, all study patients have functioning grafts, and at 1-year post-transplant, the mean blood creatinine level is 161.2 mumol/l. In the control group, one patient died of CMV infection, and 2 other grafts failed due to rejection. No adverse effect of antibody administration was observed, and hematological changes remained of minor importance. Viral infections were not observed, except one case of herpes simplex. Comparatively, clinical CMV infections occurred in 3 patients receiving ALG (15 percent). Our data suggest that a combination anti-IL-2 monoclonal antibody, cyclosporin and low-dose steroids can safely be administered to allograft recipients, avoid severe viral infections, and, in our early experience, is as potent as the powerful combination ALG, cyclosporin and high-doses steroids in preventing allograft rejection.

Adult↗
PubMed1991

[Arterial stenosis in the renal graft. Spontaneous evolution in 40 cases].

From January 1976 to June 1989, 138 renal artery stenoses (RAS) occurred in a population of 1,200 renal transplantations in a single center (11.5 percent). An interventional procedure was performed in 89 patients: surgery in 39 and transluminal angioplasty in 50. Six other patients were excluded from the study because of complications and RAS spontaneously disappeared in 3 patients. Finally, 40 patients were treated medically with a mean follow-up of 57.6 months (range 12 to 116 months). In this group, the actuarial graft survival rate did not significantly differ from that of the 2 other groups. One patient only lost his graft from renal artery thrombosis. The mean serum creatinine level at the time of RAS diagnosis (140 +/- 8.6 mumol/l) was not significantly different from the mean serum creatinine level at the last follow-up (146 +/- 14.6 mumol/l). The degree of hypertension, graded on the number of anti-hypertensive drugs, was not different at the time of diagnosis and at the end of follow-up. In conclusion, in our experience, the spontaneous course of RAS does not result in an increased rate of graft failure or impaired long-term renal function.

Adult↗
PubMed1991

[Urologic complications in kidney transplantations. Indication for endo-urologic techniques].

We report the incidence of urological complications in a series of 1,200 kidney transplant: 3.8 percent of the patients developed a urinary fistula, due to ureteral necrosis in 48 percent of cases, and 6.5 percent had urinary obstruction. Urinary fistulas are early complications appearing 20 days after the transplantation, while obstructions appear about one year after grafting. These complications are now usually treated by percutaneous and/or endoscopic techniques.

Anastomosis, Surgical↗
PubMed1991

EBV cell-lines (LCL) and E- cells as stimulator cells for limiting dilution analysis (LDA) of alloreactive IL-2-secreting cells (IL-2-SC) and cytotoxic precursors (CTLp). Comparison of their stimulator capacity and ability to generate specific alloreactivity.

The choice of stimulator cells is crucial in determining the frequency of alloreactive cells by limiting dilution analysis (LDA). In humans, E- cells or EBV-lymphoblastoid cell lines (LCL) are available for this purpose. The E- cells have been mostly used until now, but they appear to stimulate much less than LCL in other models. Consequently, we undertook a systematic comparison of the efficiency of both types of cell for the LDA of alloreactive IL-2-secreting cells (IL-2-SC) and cytotoxic precursors (CTLp). We show that LCL are stronger stimulator cells both for IL-2 secretion and for cytotoxicity induction. However, high levels of non-allogeneic reactivity were also induced. Therefore, to measure the frequency of specific alloreactive IL-2-SC and CTLp, T cells were depleted of such irrelevant reactive cells by a suicide technique: culture with autologous LCL in the presence of BUDR and use of the remaining live cells as responding effectors in LDA. Using this methodology, no non-allogeneic reactive T cells remain in the responding cells: after restimulation by autologous LCL, no IL-2-SC could be seen and no cytotoxic activity could be observed against autologous, irrelevant or LAK sensitive targets. In contrast, the number of IL-2-SC and CTLp against allogeneic targets was preserved. Therefore with this methodology, the strong stimulator capacity of LCL could be used whereas non-specific activation could be avoided in order to assess the frequency of allo-specific IL-2-SC and CTLp.

Bromodeoxyuridine↗
PubMed1990

Persistence of donor-specific IL-2-secreting cells and cytotoxic T lymphocyte precursors in human kidney transplant recipients evidenced by limiting dilution analysis.

The low reactivity to donor alloantigens reported in PBL from kidney transplant recipients might be related to clonal deletion and/or suppression of donor-specific alloreactive cells. To discriminate between these two hypotheses, we quantified the number of IL-2 secreting cells (IL-2-SC) and of cytotoxic precursors (CTLp) in the T cells from tolerant recipients when stimulated with either donor specific or nonrelated third-party LCL. To eliminate the irrelevant reactivity, we used as responding cells high-density T cells that had been depleted of such reactivity by 4 days preculture with autologous lymphoblastoid cell line in the presence of bromodeoxyuridine. Thus, frequencies of IL-2-SC and CTLp specifically directed at alloantigens could be measured. In 11 recipients, there was no strong decrease in the frequency of donor-reactive T cells when compared to the frequency of those directed at a third-party lymphoblastoid cell line, either for IL-2-SC (tested in 11 patients) or for CTLp (tested in 6 patients). In three cases of seven, a suppression was observed only when T cells were stimulated by donor cells. These data suggest that donor-reactive cells are still present in PBL of kidney-transplant recipients tested from 6 mo to 4 y posttransplantation. Moreover, suppression of donor-specific cells can be demonstrated in peripheral T cells of some recipients, which may account in part for the absence of rejection.

Histocompatibility↗
PubMed1990

Decreased lymphokine-activated killer cells in kidney transplant recipients. Correlation with a diminished number of CD3-/NKH1+ cells.

The activity of lymphokine-activated killer cells, measured either by a clonal or polyclonal technique, was assessed in 30 kidney transplant recipients (TX), in 13 hemodialyzed patients (HD-CRI), and in 18 normal (N) controls. A highly significant decrease of the LAK activity in TX in comparison with HD-CRI or N (P = 0.0001) was observed. Moreover, the percentage of CD3-/NKH1+ cells was decreased in TX in comparison with N (P = 0.01). LAK activity was strongly correlated (r = 0.72; P = 0.0001) with the percentage of CD3-/NKH1+ cells and not with that of double-positive CD3+/NKH1+ cells. Multivariate analysis showed that the sole independent variable that determined the LAK activity was the percentage of CD3-/NKH1+ cells: the pathological status (TX, HD-CRI, and N) variable was statistically not significant. On the other hand, two T cell-specific functions (IL-2 secretion and specific cytotoxic activity) were, on the whole, preserved in TX. Altogether, these results suggest that TX are LAK deficient predominantly because they have a decreased number of CD3-/NKH1+ cells. The normality of T cell functions suggests that the high rate of malignancies seen in TX is related to this LAK deficiency. Moreover, our study indicates that, in vivo, CD3+ cells do not significantly contribute to the LAK precursors.

Antigens, CD↗
PubMed1989

IL-2 receptors on circulating natural killer cells and T lymphocytes. Similarity in number and affinity but difference in transmission of the proliferation signal.

IL-2-binding sites expressed on purified circulating NK cells and high density T lymphocytes were enumerated in 125I-IL-2 binding assays and analyzed by autoradiography after chemical cross-linking of IL-2 to the cells. Quite similar profiles of IL-2R were exhibited by both types of cells consisting of the simultaneous expression of approximately 150 high affinity Tac+ receptors/cell (Kd congruent to 19 pM) and of approximately 540 intermediate affinity Tac- receptors/cell (Kd congruent to 800 pM) which appeared, in cross-linking experiments, to be the isolated 70-kDA protein (p70) subunit of the 55-kDa protein (p55)/p70 heterodimer. The high affinity receptors were distributed on less than 3% of the cells and could be eliminated by complement lysis with anti-p55 mAb. In these conditions, Scatchard analysis no longer revealed two classes of binding sites but only one class of binding sites with intermediate affinity. Although expressed in equal numbers on the surface of NK cells and resting T lymphocytes, the constitutive p70 chains seemed to transmit differently the proliferation signal after effective ligand interaction. Thus, NK cells proliferated strongly in the presence of only 260 pM IL-2, (40 U/ml), whereas resting T cells remained unresponsive to IL-2 concentrations able to saturate the existing p70 receptors (6.5 nM IL-2, 1000 U/ml IL-2) unless monocytes were present. The initiation of cell division seemed to involve the synthesis of p55 chains and the constitution of high affinity receptors as introducing anti-Tac antibody at the start of the cultures inhibited IL-2-induced proliferation. Tac mRNA transcripts accumulated rapidly in NK cells during a 18-h observation period whether anti-Tac antibody was present or not during IL-2 stimulation. In contrast a weak Tac mRNA induction was observed in resting T cells in the same conditions.

Dose-Response Relationship, Immunologic↗
PubMed1989

Recurrent essential mixed cryoglobulinemia in renal allografts. Report of two cases and review of the literature.

This report describes two patients in whom essential IgG-IgM mixed cryoglobulinemia (EMC) glomerulonephritis led to end-stage renal disease. Both patients underwent primary hemodialysis, and during the period of uremia clinical and biological manifestations of the disease fully resolved. Transplantation was performed, and in both cases cryoglobulinemia quickly recurred (30 days and 6 months after transplantation, respectively) with clinical renal and extrarenal flare, and reappearance of the biological markers of the disease (decrease in C3 and C4 components of serum complement, detection of rheumatoid activity and of cryoglobulinemia in the serum). The literature on EMC glomerulonephritis leading to end-stage renal disease is reviewed. Factors that may have contributed to extinguishing the disease and to further recurrence following transplantation-consequences of uremic state, alloimmunization and intercurrent infectious disease-are discussed.

Adult↗