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P Amlot

Publications and source records attributed to P Amlot.

At least 37 records · Page 2Linked to original sources
PubMed1992

[New perspectives in oncology: is selective destruction of tumor cells with immunotoxins in Hodgkin's disease an additional therapeutic alternative?].

In the present paper, the authors describe the production and testing of immunotoxins for clinical application in Hodgkin's disease. The immunotoxins were constructed by chemical coupling of deglycolysated ricin-A to monoclonal antibodies against antigens on Hodgkin's and Reed-Sternberg cells (CD25, CD30, IRac). The cytotoxic effect of the immunotoxins was investigated in vitro against Hodgkin's and Reed-Sternberg cells (H-RS) and in vivo against solid Hodgkin's tumors in nude mice and disseminated Hodgkin's tumors in SCID mice. Cross-reactivity with normal tissue and the staining behaviour observed in sections of Hodgkin's tissue of various subtypes proved important parameters for the assessment of clinical applicability. Of more than 30 evaluated MoAb's, eight immunotoxins were produced, of which six showed both, cytotoxic effects of considerable potency against Hodgkin's tumor cells and low cross-reactivity with vital human organs. The most effective immunotoxin, RFT5 gamma 1.dgA, (CD25) inhibits the growth of H-RS cells at concentrations of 7 pMol and destroys about 60% of solid Hodgkin's tumors of 0.5 cm in diameter in nude mice. This immunotoxin binds to virtually all tumor cells in more than 90% of patients with Hodgkin's disease. Sufficient quantities of RFT5 gamma 1.dgA were produced for the treatment of patients with refractory Hodgkin's disease. These patients are currently being treated in a phase I clinical trial.

Animals↗
PubMed1992

Chimeric CD7 monoclonal antibody therapy in rheumatoid arthritis.

Murine monoclonal antibody (Mab) therapy in patients with rheumatoid arthritis (RA) produces an antimouse immunoglobulin response by the recipient. We studied a chimeric (human/mouse) CD7 Mab, in a dose ranging tolerability study in 10 patients with RA. Modest improvements in disease activity occurred with frequent acute adverse effects of malaise, fever and nausea. After treatment, peripheral blood T lymphocyte numbers fell by 50% and CD7 expression fell by 97% for less than 7 days. Our study demonstrates chimeric Mab function in vivo and illustrates the influence of antibody isotype and patient characteristics on adverse effects.

Adult↗
PubMed1991

Immunotoxins constructed with anti-CD25 monoclonal antibodies and deglycosylated ricin A-chain have potent anti-tumour effects against human Hodgkin cells in vitro and solid Hodgkin tumours in mice.

Twenty-three monoclonal antibodies (MAbs) against the IL-2 receptor alpha-chain (CD25) were evaluated as ricin A-chain immunotoxins for the treatment of Hodgkin's disease. Primary screening used an indirect assay in which the cells were treated with the test antibody followed by a Fab' immunotoxin against mouse immunoglobulin. This screening identified 5 MAbs which inhibited protein synthesis in L540 Hodgkin cells by 50% at a concentration (IC50) of 6 x 10(-11) M or less: RFT5 gamma 1, RFT5 gamma 2a, B-B10, B-F2 and B-G3. These MAbs were then linked directly to deglycosylated ricin A-chain (dgA) and were confirmed to have potent and specific toxicity for L540 cells. The immunotoxins had the following potency order: RFT5 gamma 1 greater than RFT5 gamma 2a greater than B-B10 greater than B-F2 greater than B-G3. The most effective immunotoxin, RFT5 gamma 1.dgA, had an IC50 value of 7 x 10(-12) M, which is the same as that of whole ricin. In vivo, a single intravenous injection of 48 micrograms of RFT5 gamma 1.dgA, RFT5 gamma 2a.dgA, B-B10.dgA or B-F2 induced lasting complete remissions in 78, 66, 50 and 44%, respectively, of nude mice bearing subcutaneous solid L540 tumours of 0.7 cm diameter. Two tumours which regrew after B-B10.dgA treatment were re-established in tissue culture. Both had reduced sensitivity to B-B10.dgA in vitro but not to immunotoxins recognizing different antigens on Hodgkin cells. The MAbs that produced the most potent immunotoxins, RFT5 gamma 1, RFT5 gamma 2a and B-B10, had no significant cross-reactivity with normal human tissues outside the lymphoid system as judged from indirect immunoperoxidase staining of frozen sections. By contrast, B-F2 strongly stained normal human renal tubules.

Animals↗
PubMed1991

Phase I immunotoxin trial in patients with B-cell lymphoma.

Fifteen patients with refractory B-cell lymphoma were treated in a Phase I dose escalation clinical trial with a highly potent immunotoxin consisting of the Fab' fragment of a monoclonal anti-CD22 antibody (RFB4) coupled to chemically deglycosylated ricin A chain. All patients had low, intermediate, or high grade non-Hodgkin's lymphoma. The immunotoxin was administered i.v. in two to six doses at 48-h intervals. The peak serum concentration and the t1/2 were not dose dependent among patients and averaged 1.3 micrograms/ml and 86 min, respectively. Three patients made antibody against A chain, and a fourth made antibody against both A chain and mouse immunoglobulin. Antibody responses were low (less than or equal to 85 micrograms/ml) in three patients and were not detected until 1 mo after treatment. The maximum tolerated dose of the immunotoxin was 75 mg/m2. Dose-related toxicities included vascular leak syndrome, fever, anorexia, and myalgia. Dose-limiting toxicities included pulmonary edema and/or effusion, expressive aphasia, and rhabdomyolysis (resulting in reversible kidney failure). There was no evidence of liver dysfunction. Partial responses were achieved in 38% of evaluable patients, and in those patients who had greater than 50% CD22+ tumor cells, 50% of the patients achieved a partial response. Clinical responses were not related to tumor grade and were generally transient, lasting between 1 and 4 mo.

Adult↗
PubMed1991

Independent clonal origin of T- and B-cell clones in a composite lymphoma.

We present a detailed immunohistological and genotypic analysis of an unusual case in which a peripheral T-cell lymphoma, with features of Lennert's and angioimmunoblastic lymphoma, occurred after treatment of a low grade plasmacytoid lymphoma. By analysis of immunoglobulin and T-cell receptor genes, we show that the two diseases had an independent clonal origin at the level of lymphoid commitment. However, by employing a novel polymerase chain reaction-based technique for analysis of B-cell clonality, we show the persistence of a residual minor clonal B-cell population in the subsequent T-cell lymphoma. Only 2 previous cases of composite lymphoma involving B- and T-cell clones have been demonstrated by molecular analysis. This study underlines the immunophenotypic and genotypic heterogeneity of peripheral T-cell lymphomas and illustrates an unusual disease course in which a T-cell lymphoma has arisen in the context of, and perhaps as a consequence of, a B-cell lymphoma.

B-Lymphocytes↗
PubMed1990

Antitumor effects of ricin A chain immunotoxins prepared from intact antibodies and Fab' fragments on solid human Hodgkin's disease tumors in mice.

Three monoclonal antibodies which strongly bind to Hodgkin and Reed-Sternberg cells and two corresponding Fab' fragments were linked to deglycosylated ricin A chain (dg A) to evaluate their potential as immunotoxins for the treatment of Hodgkin's disease. Two of the antibodies, Ber-H2 and HRS-3, were shown to bind to the same epitope on the CD30 antigen, whereas the third antibody, IRac, bound to a different antigen. None of the antibodies significantly cross-reacted with normal human tissues as judged by indirect immunofluorescence and immunoperoxidase analyses on frozen sections from 28 normal tissues. All three antibodies formed potent and specific immunotoxins. They inhibited protein synthesis of the L540 Hodgkin's disease cell line in vitro by 50% at concentrations of 1 x 10(-11) M for IRac.dgA, 9 x 10(-11) M for HRS-3.dgA, and 2 x 10(-10) M for Ber-H2.dgA. HRS-3 Fab' and IRac Fab' immunotoxins were 7.8- and 60-fold less cytotoxic, respectively, than their intact counterparts in vitro. In vivo, a single i.v. injection of a dose of Ber-H2.dgA, HRS-3.dgA, or IRac.dgA corresponding to 40% of the LD50 induced lasting complete remissions in 38, 44, and 50%, respectively, of mice with solid s.c. L540 tumors of 60 to 80 mm3 size (0.5-cm diameter). At equivalent dosage (40% of the LD50), the HRS-3 Fab'.dgA and the IRac Fab'.dgA both induced lasting complete remissions in 25% of the mice, although the HRS-3 Fab'.dgA was significantly superior to IRac Fab'.dgA at retarding tumor growth in the remaining animals. The effectiveness of the immunotoxins depended on the size of the tumor at the time of injection, since IRac.dgA treatment induced complete remissions in 100% of mice with small tumors (10 to 20 mm3, approximately 0.3 cm in diameter) but only 13% of mice with larger tumors of 400 to 600 mm3 (approximately 1 cm in diameter). Tumors which regrew after IRac.dgA treatment mainly consisted of antigen-deficient mutants having reduced sensitivity to IRac.dgA but normal sensitivity to HRS-3.dgA. It is concluded that HRS-3.dgA, HRS-3 Fab'.dgA, and IRac.dgA are candidates for the treatment of Hodgkin's disease in humans.

Animals↗
PubMed1990

Immunohistology of Epstein-Barr virus-associated antigens in B cell disorders from immunocompromised individuals.

Proliferating B cell lesions developing in a series of immunosuppressed organ transplant recipients and patients with X-linked lymphoproliferative syndrome were examined for Epstein-Barr virus and cellular gene expression using immunocytochemistry and immunoblotting techniques. Results indicate that all the lesions examined from the patients in this series expressed Epstein-Barr virus gene products that were consistent with a latent, nonproductive type of infection. No lytic cycle antigens associated with productive viral infection were detected. This pattern is similar to the viral gene expression in normal B cells immortalized by Epstein-Barr virus in vitro. The demonstration in this study of Epstein-Barr virus viral gene expression in posttransplant and X-linked proliferative syndrome B cell disorders provides important new evidence for the primary role of Epstein-Barr virus in the development of these lesions. This is in contrast to the subsidiary role that the Epstein-Barr virus has in the etiology of Burkitt's lymphoma.

Antibodies, Monoclonal↗
PubMed1990

Normal immune responses in systemic sclerosis.

Cellular and humoral immune responses were assessed in 24 patients with systemic sclerosis and matched controls by immunization with a thymus dependent (TD) antigen, keyhole limpet hemocyanin (KLH), a and thymus independent (TI) antigen, dinitrophenylated Ficoll (DNP-Ficoll). Cell mediated immunity in the patients with systemic sclerosis expressed as delayed cutaneous hypersensitivity to KLH, as well as the primary T dependent and T independent antibody responses were normal. Our findings suggest that there is no generalized defect in the immune responsiveness of patients with systemic sclerosis. There is however evidence that specific defects may occur in certain subsets of patients with systemic sclerosis.

Adult↗
PubMed1989

The epitope specificity and tissue reactivity of four murine monoclonal anti-CD22 antibodies.

The CD22 antigen is expressed on the surface of normal human B cells and some neoplastic B cell lines and tumors. Previous cross-blocking studies using a panel of monoclonal anti-CD22 antibodies have defined four epitope groups, termed A-D. In the present studies, we have further dissected the epitopes recognized by four monoclonal anti-CD22 antibodies using immunoprecipitation and cross-blocking techniques, immunofluorescence analyses with a variety of cell lines, and immunoperoxidase analyses of 36 normal human tissues. Two of the antibodies, HD6 and RFB4, have been described previously, and two, UV22-1 and UV22-2, are described in this report. Our studies indicate that the four monoclonal antibodies show unexpected complexities in their reactivity with CD22+ and CD22- cells and their reactivity with solubilized CD22 molecules. The four antibodies, which recognize epitopes defined previously as CD22-A and CD22-B, further subdivide these epitope clusters into four determinants, A1, A2, B1, and B2. Furthermore, only two of the antibodies, RFB4 and UV22-2, are B cell-specific. In summary, our data indicate that RFB4 and UV22-2 would be the antibodies of choice for constructing immunotoxins to treat B cell tumors.

Animals↗
PubMed1989

T-cell receptor gene rearrangement in B-cell non-Hodgkin's lymphoma: correlation with methylation and expression.

Two of 19 B-cell non-Hodgkin's lymphoma (NHL) were found to have clonally rearranged T-cell receptor (TCR) beta chain genes with a germline TCR-gamma gene configuration. The inappropriate rearrangements had a similar structure to the TCR-beta rearrangements described in B-cell chronic lymphocytic leukemia. All cases analysed displayed a consistent germline transcription of TCR-beta and alpha chain genes which was independent of rearrangement. Consistent with this, all cases showed some degree of hypomethylation of the TCR-beta chain locus similar though distinguishable from the pattern seen in mature T cells, but quite different from that seen in normal mature B cells. Taken together, these data suggest that most NHL's arise from an immature B-lymphocyte precursor at a stage of differentiation where lineage commitment is incomplete.

Antigens, Differentiation↗
PubMed1989

Rearrangement of TCR gamma chain gene involving JP1 suggests early thymocyte origin of peripheral T-cell lymphoma.

Peripheral T-cell lymphomas (PTL) are morphologically and immunophenotypically heterogeneous. We have examined a series of cases to determine whether this heterogeneity is reflected at the level of developmentally specific T-cell receptor (TCR) gene rearrangement. 4 of 5 cases had clonal rearrangements of TCR beta and gamma chain genes; one of these also had a probable DQ52-J immunoglobulin heavy chain gene rearrangement. 2 of the 4 TCR gamma gene rearrangements involved the most 5' J region, JP1, a characteristic of immature thymocytes. These 2 cases also had immunophenotypic features of immaturity. Taken together, our results suggest that TCR gene rearrangement is correlated with surface marker data and shows that in some cases PTL may arise from a very early stage of thymocyte maturation.

Antigens, Surface↗
PubMed1989

T10B9.1A-31 anti-T-cell monoclonal antibody: preclinical studies and clinical treatment of solid organ allograft rejection.

T10B9.1A-31 is an immunoglobulin Mk (lgMk), CD3b class, murine monoclonal antibody. It is not itself mitogenic, but it partially blocks mitogenesis produced by concanavilin-A, phytohemagglutinin, and a soluble antigen cocktail and is lytic for human peripheral blood T lymphocytes (PB-T) in the presence of fresh autologous human complement and rabbit complement. It reacts with a monomorphic epitope found on all mature PB-Ts that modulates in vitro and in vivo with the CD3/T-cell antigen receptor (TCR) complex, but unlike OKT3, which reacts with CD3 proteins, T10B9.1A-31 reacts with an epitope of the TCR alpha/beta heterodimer. Immunoprecipitation of HPB-ALL with T10B9.1A-31 or OKT3 revealed that T10B9.1A-31 does not react with the 20-to 26-kd polypeptides that compose CD3, and T10B9.1A-31 failed to bind to the PEER cell, which is CD3 gamma/delta positive, TCR alpha/beta negative. Phase 1 clinical trials demonstrated that T10B9.1A-31 caused a rapid decrease in PB-Ts and no toxic effects other than fever, chills, rigors, and transient hypotension. These side effects were absent in methylprednisolone (MP)-pretreated patients. Phase II studies revealed that T10B9.1A-31 reversed steroid refractory acute rejection in three of five renal allografts treated with cyclosporine (CyA) and prednisone (P) maintenance immunosuppression, reversed steroid and polyclonal antisera refractory rejection in three cardiac allograft recipients receiving CyA/P, and attenuated acute rejection in three of three renal patients receiving baseline azathioprine/prednisone (AZA/P) when used as primary therapy. Rerejection was not seen when patients received CyA baseline immunosuppression but was seen in patients maintained on AZA/P OKT3 was efficacious in treating rejection following T10B9.1A-31 therapy. Side effects of T10B9.1A-31 appears to reverse acute rejection crisis effectively in renal and cardiac transplantation with a low incidence of rerejection in CyA-maintained patients and with fewer, milder side effects. Sequential therapy with OKT3 is possible because OKT3 and T10B9.1A-31 are of different isotypes and idiotypes.

Animals↗
PubMed1988

The stimulation of IgM rheumatoid factor from human B lymphocytes by rheumatoid arthritis complement-activating immune complexes.

Immune complexes from rheumatoid arthritis (RA IC) and Hodgkin's disease (HD IC) sera were separated on an anti-C3g affinity column and their ability to stimulate the production of IgM and IgM RF by normal and RA B lymphocytes tested in a culture system in vitro. RA IC stimulated IgM production of which up to 91.3% had IgM RF activity. HD IC were incapable of stimulating the production of IgM and IgM RF. The stimulation of IgM and IgM RF production by RA IC required de novo protein synthesis. Both RA IC and HD IC were capable of significantly inhibiting (from 47.6 to 72.0%) pokeweed mitogen (PWM)-induced and goat F(ab)2 antihuman mu-induced B lymphocyte proliferation. Thus it is proposed that IC present in human pathological sera may regulate immunoglobulin production by an effect on B lymphocyte proliferation while some may, in addition, be capable of inducing IgM RF production from such cells.

Antigen-Antibody Complex↗
PubMed1987

The cytoplasmic expression of CD3 antigens in normal and malignant cells of the T lymphoid lineage.

Anti-CD3 (T3) Ab reacting with different proportions of thymocytes (anti-CD3a: UCHT1, anti-CD3b: T10B9, and anti-CD3c: OKT3) were tested for cytoplasmic (cCD3) and membrane (mCD3) expression in the bone marrow, thymus, and blood in man and selected primates. The expression of cCD3a and cCD3c in the perinuclear and Golgi area of large, BrdU-incorporating, strongly TdT+ thymic blasts probably represents one of the earliest signs of T cell commitment, because these blast cells are CD1-, CD4-, CD8-, and mCD3-. The cCD3+, TdT+ cells are normally restricted to the thymus and are absent among the TdT+ cells of bone marrow. The anti-CD3b Ab used, T10B9, co-caps and co-modulates with the other anti-CD3 Ab and is a T cell-specific reagent at a membrane level but does not bind to perinuclear cCD3. Instead, this reagent cross-reacts with a filamentous cytoplasmic network in non-T cells in man and in primates S. oedipus and M. rhesus despite their T cell negativity for mCD3. The characteristics of all T-ALL cases studied: cCD3+, CD7+ along with nuclear TdT+ suggest lineage fidelity to early thymic blasts. As a marked contrast, cCD3 is absent in common ALL and in AML, including cases that concomitantly express CD7 and myeloid antigens. Thus, the cCD3, TdT combination provides a very sensitive assay for residual T-ALL blasts outside the normal thymus.

Adult↗
PubMed1986

Histamine release from peripheral blood leucocytes in egg-allergic patients.

Twelve egg-allergic patients were selected on the basis of a clinical history of egg allergy and a positive skin-prick test (SPT) to whole egg. A study was then carried out on the ability of the patients' washed leucocytes to release histamine in the presence of whole egg, ovomucoid, ovalbumin and ovotransferrin. Histamine release (HR) from washed leucocytes was demonstrated in ten out of twelve patients, but only four out of ten released over 40% of their total histamine. Spontaneous HR ranged from 2.1-14.5% with a mean of 7.5%. There was good agreement between positive and negative HR, skin test and radioallergosorbent test (RAST) results. Concordance between the HR and skin test was found in 83%, HR and RAST in 71% and skin test and RAST in 78% of patients. However there was poor quantitative agreement between these three tests. When skin-prick tests and HR thresholds were compared, ovomucoid elicited the greatest skin test sensitivity in five out of six patients, whereas five of the same six were more sensitive to ovalbumin when judged by HR.

Adolescent↗
PubMed1984

A single step radial immunodiffusion (RID) method for the quantitation of monomeric IgM.

Monomeric IgM (7S IgM) is present in the serum of patients with certain inflammatory and neoplastic conditions. In the past it has been necessary to separate 7S IgM from 19S IgM by chromatography or ultra-centrifugation prior to its quantification, however, 7% agarose gels allow migration of 7S molecules while retarding the migration of larger (19S) molecules. We describe the development of a RID method on 7% agarose and detail the optimum conditions for the preparation of gels and standards in order to quantify 7S IgM present in serum in a single step without prior separation from 19S IgM. The major difficulties encountered were in the preparation of the agarose gels and the conditions necessary to overcome the difficulties are described. A linear relationship was found between the ring diameter squared and the 7S IgM concentration. The assay could detect as little as 15 micrograms/ml of 7S IgM. Within assay variability was 15.4%. In the sera of 45 normal individuals monomeric IgM was not detected whereas 15 (43%) of an unselected group of patients with rheumatoid arthritis had measurable levels of 7S IgM. This method for quantifying 7S IgM is both simple and inexpensive, and because of the ease with which large numbers of sera can be processed in a single assay it is less time consuming than other methods used to quantify 7S IgM.

Humans↗