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W M Howell

Publications and source records attributed to W M Howell.

At least 73 records · Page 4Linked to original sources
PubMed1994

Detection of T-cell receptor beta chain mRNA in frozen and paraffin-embedded biopsy tissue using digoxigenin-labelled oligonucleotide probes in situ.

In situ hybridization techniques using a cocktail of digoxigenin-labelled T-cell receptor (TcR) constant (C) region beta oligonucleotide probes were used to detect TcR beta mRNA in frozen and paraffin-embedded tissue sections. The specificity of the C beta cocktail was confirmed by Northern blot analysis. The TcR C beta cocktail successfully hybridized to T cells in frozen and paraffin-embedded tissue obtained from patients with inflammatory arthropathies, B- and T-cell non-Hodgkin's lymphoma (NHL), and reactive tonsillitis, and showed staining patterns comparable to those obtained by conventional immunohistological detection of T cells. This is the first report of in situ studies using labelled TcR C beta oligonucleotide probes and may indicate the feasibility of investigating clonal T-cell populations using digoxigenin-labelled clonospecific probes in clinical samples in situ.

Biopsy↗
PubMed1994

Polymerase chain reaction amplification analyses of clonality in T-cell malignancy including peripheral T-cell lymphoma.

Clonality in T-cell malignancy was investigated using T-cell receptor (TcR) V beta 1-20 family primers and polymerase chain reaction amplification (PCR) of cDNA prepared from tissue biopsies and blood involved with tumour. Secondary PCR amplification of the VDJ joints of primary PCR products was performed to distinguish clonal from polyclonal products, and clonal V beta gene products were confirmed by direct PCR sequencing in the majority of cases. In eight T-cell malignancies including T-cell acute lymphoblastic leukaemia (T-ALL) and T-cell chronic lymphocytic leukaemia (T-CLL) shown to be clonal by Southern blot analysis, one or two primary PCR products were identified and shown to be clonal. In five cases of peripheral T-cell lymphoma (PTCL) all V beta 1-20 families were identified after primary PCR amplification, and clonal products were identified in two cases after secondary amplification; TcR V beta clonal families could not be demonstrated in the remaining three cases. These data were in agreement with previous Southern blot analysis of these cases, and confirmed the presence of reactive T cells in PTCL as well as providing further evidence for the genotypic heterogeneity of this entity. In the remaining case, a blood lymphocytosis, primary PCR amplification produced predominant TcR V beta 6 and V beta 12 family products, of which the V beta 6 family proved clonal after secondary PCR amplification. There was no evidence for overrepresentation of TCR V beta families by the tumour populations in this study, furthermore the data confirm the involvement of reactive cells in T-cell malignancy and the genetic heterogeneity of PTCL.

Base Sequence↗
PubMed1993

Absence of strong HLA-DR/DQ-DP linkage disequilibrium in the British and French Canadian Caucasoid populations.

HLA-DR/DQ-DP linkage disequilibrium was investigated in healthy, unrelated British (n = 150) and French Canadian (n = 67) Caucasoid subjects. HLA-DR and DQ typing was performed by Taq I DNA-RFLP analysis, while DPB1 typing was performed by PCR-SSOP. chi 2 and Fisher's exact tests were performed for all 2-locus biallelic comparisons and coefficients of linkage disequilibrium determined. In the British population, only one example of linkage disequilibrium, significant at P = 0.05 (after correction for the number of comparisons made) was seen (DPB1*0101-DRB1*0301[17(1)]). Additional associations, significant at P = 0.05 before correction for the number of comparisons were also seen, including DPB1*0401-DRB1*15, DPB1*1101-DRB1*0701(7(1)), DPB1*1701-DRB1*0701/ 2(7(2)), DPB1*0101-DQA1*0501, DPB1*0401-DQA1*0102, DPB1*0501-DQA1*0102, DPB1*0101-DQB1*0201, DPB1*0401-DQB1*0602/0603 and DPB1*1101-DQB1*0201. With one exception (DPB1*1101-DQB1*0201), none of these associations was seen in the French Canadian group. These results indicate that although more frequent than thought hitherto, HLA class II linkage disequilibrium involving DPB1 alleles is generally weak, and can differ even between different caucasoid populations. This may have implications for HLA and disease studies.

Alleles↗
PubMed1993

Genotypic heterogeneity of node based peripheral T-cell lymphoma.

PTCL represents a diverse group of histological entities that defy classification schemes based on normal T cell differentiation, differ in their clinical presentation and behave unpredictably. Genetic analyses of this phenotypically heterogeneous group have clearly shown that histologically defined PTCL may be subdivided on the basis of clonal gene rearrangements. The absence of clonal gene rearrangements in a significant proportion of PTCL cases has increased the complexity of classification. The data presented in this review suggest that a molecular classification would allow true reflection of PTCL aetiology, but carefully coordinated studies are required to evaluate the clinical usefulness of such a classification scheme.

Clone Cells↗
PubMed1992

T-cell receptor variable (V) gene usage by lymphoid populations in T-cell lymphoma.

A panel of monoclonal antibodies specific for TcR V gene families was used to study TcR V region expression in 28 cases of malignant and reactive T-cell expansions including four cases of mixed cellularity Hodgkin's disease (HD) and five reactive cases. TcR V beta 5 gene products were represented in three cases of lymphoblastic malignancy (V beta 5.1, V beta 5.2) and two cases of peripheral T-cell lymphoma (PTCL) (V beta 5.1). In the PTCL cases, the expanded family was found in the absence of clonal TcR gene rearrangements and in one of these cases with Ig JH and Ck clonal gene rearrangements consistent with the presence of a phenotypically and histologically undetectable clonal B-cell population. In a third PTCL case not investigated for genotype, the TCR V alpha 12 family was overrepresented. Expanded TcR V alpha 2 and V beta 5.1 families were identified in HD and V beta 8 and V beta 5.2/V beta 5.3 families in a reactive lymph node and CD3 and CD8-positive blood lymphocytosis respectively. Further study of PTCL and related entities are needed to establish whether expanded TcR families are common in those cases that fail to exhibit clonal TcR gene rearrangement.

Antibodies, Monoclonal↗
PubMed1991

Is adult-onset coeliac disease due to a low-grade lymphoma of intraepithelial T lymphocytes?

Enteropathy-associated T-cell lymphoma commonly presents with malabsorption, and debate continues as to whether adult-onset coeliac disease (CD) is itself a form of low-grade lymphoma. A 59-year-old man with adult-onset CD required resection of a segment of oedematous jejunum. Histological examination of this tissue revealed an intense intraepithelial lymphocytosis. Immunophenotypic (CD3-, CD4-, CD8-, CD34-, and CD45 RO-) and cytogenetic (deletion of the Y chromosome and chromosome 9) abnormalities were found, together with monoclonal T-cell-receptor gene rearrangements. Some patients with adult-onset CD may have low-grade lymphoma from the outset of their illness.

Biopsy↗
PubMed1991

Variable X-chromosome DNA methylation patterns detected with probe M27 beta in a series of lymphoid and myeloid malignancies.

In this study the X chromosome probe M27 beta was used to investigate DNA methylation at the DXS255 locus and hence X inactivation status and determination of tumour clonality in blood, bone marrow and biopsy tissue involved with morphologically and phenotypically defined lymphoid and myeloid disease from 14 female patients along with uninvolved bone marrow from two control individuals. Thirteen out of 16 individuals (81%) were restriction fragment length polymorphism (RFLP) heterozygous for DXS255. DNA methylation status could not be assessed in the three DXS255 homozygous individuals. In eight DXS255 heterozygous individuals clonality was clearly demonstrated using M27 beta and in six of these cases independent analysis using T cell receptor (TcR) and immunoglobulin (Ig) gene probes confirmed the presence of clonal tumour cell populations. In the two controls, polyclonality was inferred from M27 beta probe analysis. In the remaining three cases (all acute lymphoblastic leukaemia (ALL)) both DXS255 X chromosome sequences appeared to be methylated. Clonality in these cases was demonstrated by TcR or Ig monoclonal gene rearrangements. These data demonstrate the value of the M27 beta probe for determining tumour clonality in a number of cases with lymphoid and myeloid disease but indicate that there may not always be a complete correlation between DNA methylation. X inactivation status and tumour clonality in certain lymphoid neoplasms, restricting the use of this probe in clonality studies. Correlations between DNA methylation, X inactivation status and stage of normal and neoplastic T and B cell development require further investigation.

Antigens, Neoplasm↗
PubMed1991

Detection of IL-2 at mRNA and protein levels in synovial infiltrates from inflammatory arthropathies using biotinylated oligonucleotide probes in situ.

A non-radioactive in situ hybridization method for IL-2 mRNA detection based on the use of four biotinylated oligonucleotide probes, plus appropriate positive and negative control probes was developed and applied to synovial surgical and needle biopsies from rheumatoid arthritis (RA), spondyloarthropathy (SpA), psoriatic arthritis (PsA) and juvenile chronic arthritis (JCA) patients. In eight surgical biopsies (six RA, one SpA, one PsA) this non-radioactive system showed similar sensitivity to that of a previously described 32P-labelled probe system, and in addition detected IL-2 mRNA in five out of seven biopsies from SpA and PsA patients and in two out of two JCA needle biopsies. IL-2 mRNA was found in the absence of IL-2 protein in RA biopsies (six surgical, 12 needle), but variable amounts of IL-2 protein were detected in six out of seven needle biopsies from SpA, PsA and JCA patients, where CD3+ lymphoid infiltrates were present. These data suggest differences in IL-2 regulation and expression in RA and non-RA inflammatory arthropathies.

Adolescent↗
PubMed1991

No association between susceptibility to multiple sclerosis and HLA-DPB1 alleles in the French Canadian population.

HLA-DPB1 typing was performed using polymerase chain reaction DNA amplification and sequence-specific oligonucleotide probing (PCR-SSOP) which permitted identification of 17 distinct DPB alleles using 15 oligonucleotide probes. The accuracy of this approach was confirmed in an initial study of 26 human B-lymphoblastoid cell lines which demonstrated close agreement between PCR-SSOP and PLT assigned types. A cohort of 47 adult French Canadians was then studied to provide an estimate of DPB1 allelic frequencies in an ethnically homogeneous population. DPB1*0401 was the most frequent phenotype (61.5%) and only DPB1*0101, 0301 and 0402 were also present at frequencies greater than 10%. HLA-DPw4 has been reported to be associated with multiple sclerosis (MS) but our PCR-SSOP analysis of 52 French Canadian MS patients showed no association with either the DPB1*0401 or DPB1*0402 splits of DPw4 or with any other DPB1 allele.

Alleles↗
PubMed1991

HLA DPB1 alleles and susceptibility to rheumatoid arthritis.

HLA-DPB1 genotypic and phenotypic frequencies were investigated in a series of 35 adult rheumatoid arthritis (RA) patients and 42 controls. No significant associations between DPB1 alleles and susceptibility to RA were demonstrated, although some non-significant differences in DPB1*0301 and 0401 allele frequencies between patients and controls were observed.

Alleles↗
PubMed1991

An investigation of T-cell subset phenotype and function in the rheumatoid synovium using in situ hybridization for IL-2 mRNA.

Cryostat sections of synovial biopsy tissue from patients with active rheumatoid arthritis (RA), spondyloarthritis (SpA) and osteoarthritis (OA) have been investigated for interleukin-2 (IL-2) mRNA and protein production. In situ hybridization using 32P-labelled oligonucleotide probes based on IL-2 gene sequences coded by exon 1 and exon 3 of the IL-2 gene revealed IL-2 mRNA over lymphoid aggregates in RA and SpA tissue. No IL-2 mRNA was detected in OA tissue and reflected the absence of lymphoid infiltrates in these tissues. Total mRNA, as detected by a 32P oligo dT probe, was found in all tissue examined. IL-2 protein product was detected by monoclonal antibody staining in SpA but not in RA or OA tissue. This is the first report of in situ studies of lymphoid function in the microenvironment of the RA synovium. Whether these data reflect the function of normal CD3+ CD4+ CD45RO+ T-cell subsets in the diseased joint remains to be resolved.

Aged↗
PubMed1990

Clonality of T cell and phenotypically undefined lymphoid neoplasms: the value of genotypic analyses.

The value of genotypic analysis for routine assessment of leukaemia and lymphoma was shown by the findings in a selected series of 30 cases. T cell receptor (TcR) gene rearrangements were observed in six out of nine cases of CD3+ CD8+ lymphocytoses and provided clear evidence for clonality in this group. The T cell proliferations in two of the remaining cases masked B cell lymphocytic leukaemia and hairy cell leukaemia, while in the third case no cause was found for the polyclonal proliferation. Heterogeneity of phenotype and genotype were observed in peripheral T cell lymphomas: one out of six cases showed TcR gene rearrangement, one case retained its germline configuration, a further case masked B cell lymphoma and the remainder were polyclonal. Genotypic analysis was helpful in the analysis of a tumour of mixed T cell and myeloid phenotype which was shown to be germline for TcR and immunoglobulin genes, consistent with a myeloid origin. Two histiocytic tumours were found to have clonal rearrangement of TcR genes. Nine out of 11 B cell tumours showed immunoglobulin gene rearrangement. It is concluded that genetic analyses are useful in the analysis of T cell, histiocytic, and B cell tumours in which an immunoglobulin phenotype cannot be defined.

Antigens, CD↗