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T J Hamblin

Publications and source records attributed to T J Hamblin.

At least 55 records · Page 3Linked to original sources
PubMed1995

Differential usage of an autoantibody-associated VH gene, VH4-21, by human B-cell tumors.

Selection of immunoglobulin variable region genes for recombination in B cells takes place from among those VH and VL gene segments available in the unrearranged germ line repertoire. In the case of neoplastic B cells, there is apparent deviation in the use of V-genes from that expected on a random basis, both for VH and for VL. Also, the preferred V-genes, and their patterns of mutation, differ among the various categories of B-cell tumor possibly reflecting the distinct origins and clonal histories on the individual tumor cells. This review focuses on a single VH gene, VH4-21, which is a member of the VH4 family, and which appears selectively to encode immunoglobulins with autoantibody activity, particularly anti-red cell antibodies. The pattern of usage of this VH gene by B-cell tumors demonstrates clear asymmetry among different tumor types. Also, the mutations detected in this relatively non-polymorphic gene indicate that antigen, possibly autoantigen, may influence the behavior of the tumor cell.

Agglutinins↗
PubMed1994

Idiotypic vaccination against human B-cell lymphoma. Rescue of variable region gene sequences from biopsy material for assembly as single-chain Fv personal vaccines.

Idiotypic determinants on neoplastic B cells could provide tumor antigens for vaccination of patients with B-cell tumors. Because this approach requires an individual vaccine for each patient, simple methods for obtaining idiotypic antigen are desirable. Using polymerase chain reaction (PCR) with family-based V-gene and J-region primers, the variable region genes of heavy and light chains (VH and VL) of Ig have been obtained from biopsy material from 13 patients with B-cell tumors. In each case, analysis of random clones derived from the PCR product showed repeated, clonally-related sequences, whereas normal lymphoid tissue generated no repeated sequences. In 3/3 cases, the repeated sequences were found to be the same as those in a tumor-derived hybridoma. Mutational patterns in the V-genes differed among the tumors, with follicular lymphoma tending to be more highly mutated. The individual VH and VL sequences have been assembled with a flexible linker sequence to encode single-chain Fv (scFv). The scFv sequences can be cloned into bacterial expression vectors to produce protein, or into vectors suitable for direct vaccination using naked DNA. In a model system, expressed scFv protein retained all idiotypic determinants defined by a panel of five anti-idiotypic monoclonal antibodies (MoAbs). Similarly, expressed scFv proteins from two patients were shown to react with anti-idiotypic antibodies. This approach allows production of potential vaccines from surgical biopsies within 2 to 3 weeks.

Amino Acid Sequence↗
PubMed1994

Mechanisms in removal of tumor by antibody.

We report two preliminary trials of antibody treatment of B-cell lymphoma. Advanced lymphoma was treated with chimeric FabFc2, in which mouse Fab' gamma is linked to two human Fc gamma 1 fragments so as to recruit natural effectors to tumor targets. Terminal lymphoma was treated with bispecific antibody (BsAb) which recruits the ribosome-inactivating protein saporin. These different mechanisms led to interesting differences in patterns of tumor clearance. Eight patients were treated with chimeric antibody of two specificities, each at 12 mg/kg: anti-CD37, plus either anti-CD38 or anti-CD19 according to tumor phenotype. On completion of the 3-wk treatment, residual plasma antibody had a half-life exceeding 10 d. Tumor cells in blood disappeared rapidly. However significant reductions in solid masses occurred in only three patients, becoming apparent 3-4 wk after beginning treatment and then continuing slowly. Five patients were treated with preformed immune complexes of saporin and F(ab' gamma)2 BsAb. Although doses of saporin reached 10 mg weekly, contact with the tumor can only have been fleeting: plasma antibody was undetectable (< 0.5 micrograms/mL) 48 h after infusion, whereas the saporin disappeared even faster and was undetectable (< 4 ng/mL) at 24 h. Tumor cells disappeared from the blood more slowly than occurred with chimeric antibody. In contrast shrinkage of extravascular tumor was more rapid, and occurred in all patients, but proved less durable.

Antibody Specificity↗
PubMed1994

Clonal history of a human follicular lymphoma as revealed in the immunoglobulin variable region genes.

The variable region genes used to encode the immunoglobulin expressed by tumour cells of a patient with follicular lymphoma have been identified and sequenced. Initially, a lymph node biopsy was analysed and revealed usage of VH and V kappa genes which had numerous substitutions as compared with the closest germ line genes. The pattern of mutations in VH was consistent with a role for positive selection by antigen. In addition, there was evidence in both VH and V kappa sequences for clonal heterogeneity. After 5 years, which included treatment with chemotherapy, the patient relapsed with tumour cells present in the blood. Analysis of the V-genes used by the emerging tumour revealed a single homogeneous sequence for both VH and VL, which, in each case, matched closely one of the sequences in the original lymph node biopsy. These results indicate that selection, possibly mediated by antigen, can operate on a cell destined to give rise to lymphoma, and that intraclonal variation can occur after the neoplastic event. However, in this case, late relapse in the blood is dominated by a single clone.

Amino Acid Sequence↗
PubMed1994

Establishing the incidence of myelodysplastic syndrome.

We studied the incidence of myelodysplastic syndrome (MDS) in a population served by one district general hospital over a 10-year period (1981-90). Cases were sought through investigation of individuals presenting with suggestive peripheral blood findings. 279 new cases were diagnosed in a population rising from 203,000 to 226,000 over the study period. The observed incidence rate did not change over the study period. The crude incidence rate was 12.6/100,000/year. Age-specific incidence rates per 100,000 per year were 0.5 for age < 50, 5.3 for age 50-59, 15 for age 60-69, 49 for age 70-79, and 89 for age 80+. A cohort study of one large general practice revealed several previously unknown and asymptomatic cases, indicating that the observed figures for the population overall may still underestimate the real incidence. We conclude that MDS is more common than reported in previous studies and that incidence continues to rise into very old age. Difficulties in case ascertainment hamper reliable estimates of true incidence.

Adult↗
PubMed1993

Autoanti-red cell antibodies synthesized by patients with infectious mononucleosis utilize the VH4-21 gene segment.

A significant proportion of patients with B cell tumors secrete IgM mAb that recognize a carbohydrate autoantigen (li) on the red cell surface. The majority bear an idiotope (Id) that arises from heavy chains encoded by the VH4-21 gene segment, indicating unusual restriction of autoantibody specificity to a single VH gene. Polyclonal anti-li antibodies are also synthesized transiently by normal B cells following certain infections, and we have analyzed the role of the VH4-21 gene in encoding these antibodies. Levels of Id in sera of patients following infection with EBV or Mycoplasma pneumoniae were significantly raised (p < 0.01), and the Id-positive Ig reacted with patients' red cells. Id-positive B cell clones were established from four EBV-infected patients, and 6/6 of the IgM-Id agglutinated red cells. Nucleotide sequence analysis revealed involvement of the VH4-21 gene in all cases, with remarkably little change from the germ-line sequence. However, D segments were heterogeneous, and light chains differed. These results indicate that the same VH gene is used both by polyclonal autoantibodies produced in response to infection, and by B cell tumors. However, the lack of mutations would not appear to give an opportunity for Ag selection to drive affinity maturation of these autoantibodies.

Adolescent↗
PubMed1993

Differential usage of an Ig heavy chain variable region gene by human B-cell tumors.

A monoclonal anti-idiotypic antibody has been raised that recognizes Igs with heavy chains encoded by a member of the VH4 family, the VH4-21 gene segment. The idiotope (Id) is detectable on a high percentage of early B cells in fetal spleen, and is expressed by certain autoantibodies, particularly cold-reactive anti-red blood cell antibodies. Therefore, it was of interest to investigate usage of this VH gene by neoplastic B cells; 81 chronic lymphocytic leukemias (CLLs) involving CD5+ B cells and 62 B-cell lymphomas of varying histologic type have been analyzed. The Id was expressed by only 3 of 81 (3.7%) of the CLLs, indicating a relatively low usage by these tumors. In contrast, the Id was expressed by 9 of 62 (14.5%) of the lymphomas across a range of histologic types, indicating a differential use of the VH4-21 gene among B-cell neoplasms. For three of the Id-positive lymphomas, each of a different histologic class, the nucleotide sequence of the tumor-derived VH gene was determined; the VH4-21 gene was identified, as expected. The sequence from the CLL was identical to the germline sequence, and the marginal zone lymphoma showed only 3 nucleotide changes, 2 of which gave rise to amino acid substitutions. In contrast, the sequence from the follicular lymphoma showed 29 nucleotide changes giving rise to 14 amino acid substitutions, which were scattered among the CDR and FW regions.

Antibodies, Monoclonal↗
PubMed1993

Idiotypic IgM on a B-cell surface requires processing for recognition by anti-idiotypic T cells.

Immunization with purified idiotypic IgM derived from the BCL1 lymphoma generates CD4-positive T cells which proliferate specifically in response to idiotypic antigen expressed at the surface of the BCL1 tumor cells. These T cells have been hybridized and two cloned hybridomas have been used to study the molecular nature of the idiotypic antigen recognized. Endogenous presentation of idiotype by the B cells generated IL-2 from the T-cell hybridomas, as measured by a CTLL response. Presentation was inhibited in a dose-dependent manner by chloroquine or ammonium chloride, both of which affect proteolytic degradation of antigen in the endosomes. Similar results were obtained with inhibitors of metabolism or protein synthesis. However, none of these reagents affected expression of idiotypic IgM at the cell surface under the conditions used, indicating that whole IgM is not interacting directly with the T-cell receptor. Interaction between the presenting B cells and T-cell hybridomas was inhibited by anti-CD4 and, in one case, by a monoclonal antibody directed against a determinant in the I-Ed region of the MHC Class II. Inhibition also occurred with antibodies against IgM, either anti-constant region or anti-idiotype, and the univalent Fab' gamma fragment was an effective inhibitor. These data indicate that the B cell constitutively presents its endogenous idiotypic immunoglobulin to CD4-positive T cells following endocytosis from the surface, proteolytic degradation, and interaction with MHC Class II molecules. This endogenous pathway is perturbed by binding of exogenous anti-immunoglobulin antibody, perhaps mimicking what might occur when surface immunoglobulin encounters antigen.

Animals↗
PubMed1993

Utilization of the VH4-21 gene segment by anti-DNA antibodies from patients with systemic lupus erythematosus.

A monoclonal antibody (9G4) which detects an idiotope (Id) rising from heavy chains encoded by the VH4-21 gene segment has been utilized to investigate the role of this gene in encoding anti-DNA antibodies in SLE. Two hybridomas secreting Id-positive anti-DNA antibodies were established from two patients with SLE, with one (RT-79) an IgM kappa and the other (D-5) IgG kappa. Nucleotide sequence analysis of the heavy chain variable regions revealed involvement of the VH4-21 gene; the IgM antibody used the gene in germ line configuration, whereas the IgG antibody had 18 nucleotide changes. The CDR3 sequences for both the antibodies had a predominance of basic amino acids, with RT-79 having five and D-5 two arginine residues respectively. The VH4-21 gene segment, often in germ line configuration, is also used by IgM autoantibodies against red cell Ii antigens. However, IgM from a panel of six hybridomas secreting antibodies of Ii specificity, had no detectable activity against DNA. Conversely, RT-79 had only a weak ability to agglutinate red cells. Comparisons of Ig variable regions indicate that the amino acids in the CDR3 region of the mu chain influence the ability of IgM encoded by the VH4-21 gene segment to discriminate between a carbohydrate Ii antigen and DNA, and strongly support the suggested role of arginine in interaction with DNA. Sera from patients with SLE were found to have significantly raised levels of Id which was expressed by anti-DNA antibodies against both ss and dsDNA.

Amino Acid Sequence↗
PubMed1993

A phase-III study of recombinant interleukin 2 and 5-fluorouracil chemotherapy in patients with metastatic colorectal cancer.

Sixteen patients with metastatic colorectal cancer have been treated with a regimen involving an 120 h continuous infusion of rIL-2, 18 x 10(6) iu m-2 day followed by three injections of 5FU 600 mg m-2 at weekly intervals. Entry criteria included no previous chemotherapy, ambulatory performance status, and a measurable lesion. In most cases side effects were easily manageable and only one patient required transfer to an intensive care unit with the capillary leak syndrome. In three patients persistent hypotension was found to be unrelated to treatment with rIL-2, being caused respectively by a line infection, pulmonary embolus, and bowel perforation. This last proved a fatal complication. Five patients (33%; [95% confidence limits, 11.8%-61.6%]) achieved a partial response, and two non-responders later achieved a partial response when treated with weekly 5FU. This regimen is currently being evaluated in a phase-III randomised controlled trial.

Abdominal Neoplasms↗
PubMed1993

A genetic approach to idiotypic vaccination.

Treatment of cancer with vaccines is an attractive prospect, but few tumours express suitable target antigens. With B-cell lymphomas, the idiotypic immunoglobulin (Ig) of the malignant B-cell should provide a suitable target but this requires a vaccine to be created for each patient. We propose a strategy for making such vaccines: first to clone the V genes of the idiotypic Ig, and second to inject the patient with the cloned DNA (genetic immunisation) in order to elicit an immune response against the encoded Ig. We have previously shown that the V genes of the idiotypic Ig can be identified from human lymph node biopsies by polymerase chain reaction amplification, cloning, and sequencing. In this report, we show that anti-idiotypic antibodies can be elicited by direct injection of an expression vector that encodes the V genes of murine antibodies (the V genes of B1.8, a murine hybridoma or of BCL1, a murine lymphoma line). This finding suggests a simple approach to the preparation of idiotypic vaccines for patients with B-cell lymphoma, which also circumvents the need for adjuvants.

Animals↗
PubMed1993

Use of a retinoblastoma gene probe to investigate clonality in Richter's syndrome.

A 69-year-old woman presented with Rai stage 0 chronic lymphocytic leukemia. Ten years later she developed a diffuse centroblastic lymphoma involving the stomach. The surface membrane phenotype of the CLL cells was MD lambda while that of the large cell lymphoma (LCL) cells was MD kappa. The two populations had different heavy and kappa light chain rearrangements. Cytogenetic analysis of the CLL cells showed a deletion involving chromosome 13, band q14, but was unsuccessful in the LCL cells. However, use of a probe (p68 RS2.0) which recognizes a variable number tandem repeat sequence in the retinoblastoma gene, localized to chromosome 13q14, showed two alleles in the LCL cells but only one in the CLL cells. These data suggest that in this case of Richter's syndrome the CLL cells and the LCL cells are clonally distinct.

Aged↗
PubMed1992

Euthanasia.

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Ethics, Medical↗
PubMed1992

VH restriction among human cold agglutinins. The VH4-21 gene segment is required to encode anti-I and anti-i specificities.

We previously reported that human autoantibodies with cold agglutinin activity contained a single human VH gene segment (VH4-21) which was also responsible for the cross-idiotypic specificity characteristic of the cold agglutinin response. To confirm and extend this observation we have analyzed at the nucleotide level the H and L chains of six new cold agglutinin molecules derived from different patients. We found that regardless of whether the antibody recognizes the i or the I red cell Ag, restriction at the VH gene segment level is absolute. We also found that even in the absence of somatic mutation the VH4-21 gene segment can encode both anti-i and anti-I specificities. Finally, although the VH4-21 gene segment is essential for cold agglutinin activity, the other genetic elements that contribute to the V region of the antibody molecules can be extremely diverse. The structural information provided in this report sharply restricts the requirement for encoding pathogenic cold agglutinin activity to one of the components of the H chain V region, specifically the VH gene segment. The implications of this apparently absolute requirement for a single VH gene segment, unprecedented in the human autoimmune response, are discussed.

Aged↗
PubMed1992

Intensive chemotherapy in myelodysplastic syndromes.

Patients with myelodysplastic syndrome (MDS) who have more than 10% blasts in their bone marrow have a very short survival. Treatment has not improved for these patients for the past 10 years and supportive care alone is still the gold standard. Intensive chemotherapy for poor prognosis MDS has been little tried, but complete remission rates are higher in such studies than in patients with acute myeloid leukaemia (AML) supervening on the MDS. Although these groups may not be comparable, and neither group is representative of the majority of patients with the MDS who are generally older, a case can be made for a randomised prospective study comparing intensive chemotherapy and supportive care alone in poor prognosis MDS. For patients with the myelodysplastic syndrome intensive chemotherapy may carry special risks. The involvement of the whole marrow in the neoplastic clone, and the likelihood of anthracycline resistance are two such hazards which may need to be circumvented.

Age Factors↗