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Biomedical subjects

G Hale

Publications and source records attributed to G Hale.

At least 127 records · Page 7Linked to original sources
PubMed1993

Efficient complement-mediated lysis of cells containing the CAMPATH-1 (CDw52) antigen.

CAMPATH-1 antibodies recognise a unique molecule on human lymphocytes and are unusually efficient at causing cell lysis with homologous complement. They have been successfully used for lymphocyte depletion in vivo in a variety of diseases. The antigen is a small glycosylphosphatidylinositol (GPI)-anchored glycoprotein with a mature peptide comprising only 12 amino acids and one N-linked glycosylation site at Asn3. The antigenic epitope is found in a proteolytic fragment containing the C-terminal tripeptide and the GPI anchor. Both the native and deglycosylated antigen as well as the proteolytic fragment can be reincorporated into various target cells, conferring sensitivity to lysis by CAMPATH-1 antibodies. These results imply that the special feature of the antigen which makes it a good target does not reside in the N-linked sugar or the first nine amino acids: instead they support the hypothesis that the proximity of the antigenic epitope to the cell membrane is more important.

Amino Acid Sequence↗
PubMed1993

The glycosylphosphatidylinositol-anchored lymphocyte antigen CDw52 is associated with the epididymal maturation of human spermatozoa.

The CAMPATH-1 (CDw52) antigen is a small glycosylphosphatidylinositol (GPI) anchored glycoprotein with a mature peptide comprising only 12 amino acids. It is abundantly expressed on human lymphocytes and is an unusually good target for complement-mediated cell lysis. The immunosuppressive and lymphocyte-depleting effects of CAMPATH-1 antibodies are being tested in a variety of diseases. Here we show that the antigen is also expressed at a high level in the male reproductive system, being found in the epididymis, seminal vesicle, seminal plasma and on the surface of mature (but not testicular) spermatozoa. Its possible transfer from epithelial cells in the epididymis to maturing sperm may represent a novel method of acquisition of cell surface antigens. In the presence of human complement, CAMPATH-1 antibodies inhibited the motility of washed sperm. However, seminal plasma blocks antibody binding and can protect sperm from this cytotoxic effect.

Antigens, CD↗
PubMed1993

CAMPATH-1 monoclonal antibody therapy in severe refractory autoimmune thrombocytopenic purpura.

Six patients with autoimmune thrombocytopenic purpura (three of whom had CLL/NHL and one previous Hodgkin's disease) refractory to conventional therapy were treated with an antilymphocyte monoclonal antibody directed at CDw52 (CAMPATH-1). We observed response in four of the five evaluable patients; in three patients the response has lasted more than 4-9 months. However, response did not occur in most cases until 4-6 weeks after the commencement of the antibody therapy, suggesting that the mechanism of action is probably that of immune modulation.

Adult↗
PubMed1993

In vitro and in vivo depletion of T cells.

Transplant related mortality and relapse after bmt have a negative influence on the outcome of patients transplanted for acute leukaemia in first remission. Transplant related mortality includes graft-versus-host disease, infections and graft failure. To prevent gvhd and associated infections without increased graft rejection, a protocol of combined in vivo/ex vivo T-cell depletion (Campath IgG 20 mg i.v. for 5 days and Campath IgM T-cell depleted graft) with no further immunosuppression was initiated. Up to now 22 adult patients (median age 39 years, range 21 to 51) have been transplanted. One graft failure most probably due to persistent leukaemia, three acute gvhd (grade I) and no chronic gvhd occurred. Two patients relapsed after bmt and died. Two further patients died due to idiopathic interstitial pneumonitis and acute liver failure, respectively. Eighteen patients are alive in complete remission. With a median follow up of 13 months (1-30) the probability of survival is 78%, disease free survival is 80% and transplant related mortality is 10%. We compared these results with 3 historical control groups with different regimens of gvhd prophylaxis. 1. MTX group (n = 15): With a median follow up of 135 (115-147) months after bmt the probability of survival is 40%, disease free survival is 40% and transplant related mortality is 60% (mainly gvhd and infection). 2. Campath group (only ex vivo T-cell depletion n = 25): With a median follow up of 86 (62-102) months probability of survival is 52%, disease free survival is 43% and transplant related mortality is 36% (mainly rejection and infection).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Matched unrelated donor bone marrow transplantation for chronic myeloid leukaemia in chronic phase: comparison of ex vivo and in vivo T-cell depletion.

Between January 1985 and March 1992, 48 patients with chronic phase CML underwent BMT from volunteer unrelated donors (MUD) serologically identical at HLA-A, B and DR loci. 19 patients received donor marrow ex vivo T-cell depleted (EX-TCD) with Campath monoclonal antibodies. 29 patients received unmanipulated donor marrow with CsA/MTX GVHD prophylaxis; 28 received additional intravenous antilymphocyte therapy from day +1 to +5 (IN-TCD). Overall 26 patients survive at median follow up of 362 days; actuarial survival at 3 years is 50%. 3 patients have sustained haematological relapse; actuarial leukaemia-free survival is 38%. There is no difference in overall survival between the EX-TCD and IN-TCD groups, but primary graft failure (n = 4) occurred only in the EX-TCD group, while GVHD (grade II or greater) occurred more frequently in the IN-TCD group (61% vs. 29%, p = 0.084). The optimum method for GVHD prophylaxis in MUD BMT remains uncertain.

Adolescent↗
PubMed1992

Humanised monoclonal antibody therapy for rheumatoid arthritis.

Monoclonal antibodies that target T cells have shown some benefit in rheumatoid arthritis although responses have not been long lasting. This is partly due to insufficient therapy consequent upon antibody immunogenicity. Use of humanised antibodies, which are expected to be less foreign to man than conventional rodent antibodies, might overcome this problem. We therefore assessed in a phase 1 open study the potential of a "lymphocyte depleting" regimen of the humanised monoclonal antibody CAMPATH-1H in 8 patients with refractory rheumatoid arthritis. Apart from symptoms associated with first infusions of antibody, adverse effects were negligible. Significant clinical benefit was seen in 7 patients, lasting for eight months in 1. After one course of therapy, there was no measurable antiglobulin response, although 3 out of 4 patients have become sensitised on retreatment. Humanisation reduces the immunogenicity of rodent antibodies but anti-idiotype responses may still be seen on repeated therapy, even in patients sharing immunoglobulin allotype with the humanised antibody.

Adult↗
PubMed1992

Interaction of avidin with the lipoyl domains in the pyruvate dehydrogenase multienzyme complex: three-dimensional location and similarity to biotinyl domains in carboxylases.

Avidin can form intermolecular cross-links between particles of the pyruvate dehydrogenase multienzyme complex from various sources. Avidin does this by binding to lipoic acid-containing regions of the dihydrolipoamide acetyltransferase polypeptide chains that comprise the structural core of the complex. It is inferred that the lipoyl domains of the acetyltransferase chain extend outwards from the interior of the enzyme particle, interdigitating between the subunits of the other two enzymes bound peripherally in the assembled structure, with the lipoyl-lysine residues capable of reaching to within at least 1-2 nm of the outer surface of the enzyme complex (diameter ca. 37 nm). The distribution of enzymic activities between different domains of the dihydrolipoamide acetyltransferase chain implies that considerable movement of the lipoyl domains is a feature of the catalytic activity of the enzyme complex. There is evidence that the lipoyl domain of the 2-oxo acid dehydrogenase complexes is similar in structure to a domain that binds the cofactor biotin, also in amide linkage with a specific lysine residue, in the biotin-dependent class of carboxylases.

Amidohydrolases↗
PubMed1992

In vivo use of Campath-1G to prevent graft-versus-host disease and graft rejection after bone marrow transplantation.

Twenty-two patients (16 male, six female; median age 34 years, range 16-49) with acute myeloid leukemia (1st complete remission (CR), n = 9), acute lymphocytic leukemia (1st CR, n = 5), chronic myeloid leukemia (chronic phase n = 5, accelerated phase n = 1), malignant lymphoma (n = 1) and myeloma (n = 1) were transplanted with unmanipulated donor bone marrow after standard conditioning including the monoclonal antibody Campath-1G daily from day -4 to day 0. No further graft-versus-host disease (GVHD) prophylaxis was given. All patients engrafted and neither graft failure nor rejection were observed. Acute GVHD grade I (skin) was seen in 12 out of 21 patients at risk. Acute GVHD grade II (skin) occurred in two patients. Severe GVHD (grade III, IV) of the gut, liver and skin developed in two patients. The overall incidence of severe acute GVHD (II-IV) was 19% of the patients at risk. Chronic GVHD (skin only) was seen in eight patients (42%) (six of extensive severity). A total of 14 patients died, the causes being relapse (four), direct cytotoxic drug toxicity (one), a GVHD (two), disseminated varicella zoster (one), systemic tuberculosis (one), interstitial pneumonitis (three) and veno-occlusive disease (two). These results indicate that the intravenous administration of Campath-1G may have reduced the incidence of severe acute GVHD without the occurrence of graft failure. However, the incidence of chronic GVHD does not appear to have decreased.

Adolescent↗
PubMed1991

Characterization of the CAMPATH-1 (CDw52) antigen: biochemical analysis and cDNA cloning reveal an unusually small peptide backbone.

The CAMPATH-1 (CDw52) antigen has been purified from human spleen. The antigenic epitope is heat stable but sensitive to mild alkali treatment. Experiments with phosphatidylinositol-specific phospholipase C indicate that it is anchored by a glycosylphosphatidylinositol (GPI) anchor. An N-terminal sequence of 11 amino acids was determined, followed by an abrupt stop. Using short overlapping mixed oligonucleotide primers, cDNA synthesized from the mRNA of a human B cell line was amplified by the polymerase chain reaction. The product was used to isolate cDNA clones and the full amino acid sequence of the CAMPATH-1 antigen was deduced. It consists of 37 amino acid residues plus a 24-residue signal peptide. It has all the features expected for a GPI-anchored membrane protein except that the predicted mature protein is remarkably short, comprising no more than 18 residues and possibly as few as 12 (depending on the GPI linkage site). Potential attachment sites for carbohydrate are present and it is shown that the antigen contains N-linked oligosaccharide(s). This structure accounts for the known properties of the antigen, though the exact reasons why it is such a good target for cell lysis in vitro and in vivo are not yet clear.

Amino Acid Sequence↗
PubMed1991

Humanized monoclonal antibody treatment in rheumatoid arthritis.

A 41-year-old woman with active, seropositive erosive rheumatoid arthritis was treated with the humanized monoclonal antibody Campath 1H. She had not responded or developed side effects to myocrisin, sulfasalazine and penicillamine, and had not responded to inpatient bedrest and physiotherapy. There was a rapid clinical improvement within 24 hours of infusion, which was maintained for about 12-14 weeks after the infusion. The lymphocyte count was suppressed for 7 months after treatment. There were no significant side effects during or after treatment. No anti-Campath 1H response was detected. This preliminary study suggests humanized monoclonal antibody therapy may be of value in the treatment of rheumatoid arthritis.

Activities of Daily Living↗
PubMed1990

Complement activation by immunoglobulin does not depend solely on C1q binding.

A matched set of rat chimeric antibodies has been studied for their ability to activate various key stages of the complement cascade. Rat IgM and IgG2b were efficient at all stages from C1q binding to cell lysis. However, for other isotypes, a direct correlation between C1q binding and cell lysis did not apply. IgG2a, which was only modestly efficient at C1q binding, was relatively more so for binding and activation of while C1, and was by far the most effective isotype after IgG2b and IgM for C4 and C3 binding. IgG2c was relatively efficient at binding C1q and C1, but less so for the binding of C4 or for later stages. IgA was efficient at binding C1, but again, this was not reflected in activation of later stages. The results suggest that properties of different isotypes, as well as influencing binding of C1q, may regulate attachment of the C1r2C1s2 tetramer. In addition, distinct features of certain isotypes may favor C4 activation and binding, independent of their ability to activate C1.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1990

"Pacecare"--a computerized database for pacemaker follow-up.

A computerized database for pacemaker follow-up has been designed to run on IBM compatible hardware and to accept pulse generator and lead models of all manufacturers. Stored data includes patient, physician and implant details, indications for pacing, underlying rhythm, complications and management, program settings, and follow-up measurements. Typing is minimized by the use of "pop-up" lists and prepared pulse generator template displays. At each follow-up visit a patient's file is retrieved by surname or number, a visit record created, and measurements documented. As the template of the previous visit is used, recording of the clinic visit takes less than 1 minute. Changes in pacing rates (base or magnet), pulse widths, lead thresholds, lead impedance, and battery cell impedance can be displayed graphically for immediate recognition of end-of-life parameters or suspected malfunction. The program will print patient, implantation and clinic visit summary reports, clinic appointment lists, letters to patients, and annual reports. Two Melbourne hospitals have now entered over 3,600 patients into the database. Valuable information has been obtained regarding implantation details and trends with pulse generator and lead usage. Pacecare is a sophisticated, yet user friendly, computerized database for pacemaker follow-up. Recording of clinic visits is fast and changes in testing parameters can be recognized immediately.

Computer Systems↗
PubMed1990

Purging in auto- and allografts: monoclonal antibodies which use human complement and other natural effector mechanisms.

CAMPATH-1M is a rat IgM monoclonal antibody which binds to an antigen on all human lymphocytes and monocytes, but which is not present on marrow stem cells (Hale et al., 1983). Lymphocytes can be efficiently killed in bone marrow buffy coat preparations using the antibody and donor human serum as a means to avoid graft versus host disease (GVHD) (Waldmann et al., 1984). An analysis of 520 matched sibling bone marrow transplants (BMT) for leukaemia demonstrates that T-cell depletion using CAMPATH-1M markedly reduces the incidence and severity of GVHD, but there is an increased risk of graft rejection. In the case of CGL in chronic phase, there is also an associated extra risk of relapse, particularly in patients where engraftment may have been compromised (Hale et al., 1988a). A rat IgG2b antibody of the same specificity as CAMPATH-1 (CAMPATH-1G) was developed which is able to both fix human complement and opsonize lymphocytes in vivo (Dyer et al., 1989). Initial studies for the prophylaxis of bone marrow rejection in 55 mismatched and matched unrelated donor (MUD) BMTs suggest that CAMPATH-1G treatment of the recipient may reduce, but not eliminate, marrow graft rejection. The broad CAMPATH-1 specificity means that it is also ideal for purging a range of lymphoid malignancies prior to autologous BMT, or even for direct serotherapy of leukaemic patients. However, there may be limitations of monoclonal antibody purging using complement or other natural effector mechanisms either in vivo or in vitro; in particular, antigenic modulation and an antiglobulin response. Phase 1 studies of "in vivo purging" with a monovalent CD3 antibody (Clark et al., 1989), and also with a genetically engineered humanized IgG1 (CAMPATH-1H) (Hale et al., 1988b) suggest that these limitations can be overcome.

Antibodies, Monoclonal↗
PubMed1989

Effect of graft perfusion with two CD45 monoclonal antibodies on incidence of kidney allograft rejection.

In a blind trial, 77 patients were randomised to receive first cadaver kidney allografts that had been perfused either with a pair of CD45 monoclonal antibodies (mAbs), in an attempt to reduce the immunogenicity of passenger leucocytes, or with control human albumin solution. No complications of mAb perfusion were observed. Patient and allograft survival were similar in both groups. Rejection episodes were recorded in 7 (18%) of the patient with mAb perfused allografts compared with 24 (63%) of the controls.

Animals↗