Clonality of B-cells in portal lymphoid infiltrates of HCV-infected livers.

Evidence has been accumulating in favour of a role for hepatitis C virus (HCV) in the pathogenesis of human lymphoproliferative disorders. HCV infection has been documented in the majority of patients with essential mixed cryoglobulinaemia type II (MC-II); in patients with HCV infection, B-cell clonal expansion have been detected in peripheral blood and bone marrow, and a high prevalence of B-cell non-Hodgkin's lymphomas has been documented. Liver biopsies in chronic hepatitis C frequently show portal lymphoid infiltrates with features of B follicles, whose clonality has not yet been investigated. This study has analysed the B-cell clonality of portal lymphoid infiltrates from 16 patients with chronic HCV hepatitis. Portal tracts showing obvious lymphoid infiltrates were microdissected from the paraffin-embedded liver tissue sections and the clonality of lymphoid B-cells was tested using a polymerase chain reaction (PCR) approach designed to identify immunoglobulin heavy chain gene (IgH) rearrangements. A successful IgH-PCR analysis was achieved in 35 lymphoid infiltrates from 11 patients (seven with the four without MC-II) and yielded a single band in 21 cases, two bands in ten cases, and three bands in four cases. Comparison of the IgH-PCR amplification bands obtained from the different lymphoid aggregates of the same biopsy revealed that they differed in size. This finding indicates that each aggregate derives from the proliferation of one or a few founder B-cells, which are not related to each other. The results obtained in patients with and without MC-II were similar, suggesting that the presence of B-cell clonal proliferations in liver biopsies is independent of the occurrence of B-cells producing monoclonal IgMk cryoglobulins.

APC gene mutations and allelic losses in sporadic ampullary tumours: evidence of genetic difference from tumours associated with familial adenomatous polyposis.

We explored APC gene mutations and chromosome 5q21 allelic losses (5qLOH) in 18 neoplasms of the papilla of Vater, including 6 early-stage tumours (3 adenomas, 3 carcinomas) and 12 advanced-stage cancers. Eleven PCR-amplified polymorphic sequences were used to analyse 5qLOH. APC mutations were investigated both by an in vitro APC-protein truncation test and by single-strand conformation polymorphism analysis. Mutations in the Ki-ras, N-ras and p53 genes were also assessed. We found: 5qLOH in 8 of 16 cases (50%), including 1 adenoma, 3 early- and 4 advanced-stage cancers; APC mutations in 2 adenomas and 1 advanced-stage carcinoma; Ki- or N-ras mutations in 3 adenomas and 3 advanced-stage cancers; p53 mutations in 2 early-stage and 7 advanced-stage adenocarcinomas. Our results suggest that 5qLOH, APC mutations and ras mutations are present at early stages, whereas p53 inactivation is associated with progression of malignancy in a large proportion of cases. These data indicate that sporadic ampullary tumours differ from those occurring in familial adenomatous polyposis in the frequency (17% vs. 64%) as well as in the site of APC somatic mutations, suggesting a different molecular pathogenesis in the 2 conditions.

Chromosome 7q allelic losses in pancreatic carcinoma.

During our DNA fingerprinting studies of paired normal and pancreatic cancer tissues using arbitrarily primed PCR, we noticed a band showing an apparent homozygous deletion in a pancreatic cancer cell line and a decreased intensity in a number of primary cancers. That band was assigned to chromosome 7. Such information led us to analyze chromosome 7 loss of heterozygosity (LOH) in a panel of 12 cryostat-enriched primary pancreatic cancers and 2 pancreatic cancer cell lines, despite the reportedly low frequency of chromosome 7 LOH in xenograft-enriched pancreatic cancers. Seventeen PCR-amplified CA-microsatellite polymorphic sites were analyzed. One of the two cell lines and eight common-type cancers (including all five poorly differentiated and three of five moderately differentiated cancers) showed chromosome 7q LOH, whereas the two uncommon types of ductal cancer (one adenosquamous and one mucinous noncystic) scored negative. Our data suggest that chromosome 7q LOH is a frequent event (80%) in cryostat-enrichable common pancreatic ductal carcinomas, that is, those primarily of high cellularity. The chromosome 7q smallest common deleted region described by our cases was between 7q31.1 and 7q32.

The complex interplay of the DQB1 and DQA1 loci in the generation of the susceptible and protective phenotype for insulin-dependent diabetes mellitus.

IDDM patients of North East Italian region were molecularly typed for their HLA-DQB1 and DQA1 loci by using allele specific oligonucleotide probes and PCR amplified genomic DNA. IDDM status strongly correlated with DQB1 alleles carrying a non-aspartic acid residue in position 57 of DQ beta chain and DQA1 alleles with an arginine residue in position 52 of DQ alpha chain. Genotype analysis revealed that individuals with two DQB1 alleles having a non-aspartic residue in position 57 and two DQA1 alleles with an arginine residue in position 52 had the highest relative risk of disease: they constituted 41% of IDDM patients as compared to 0% of controls. Heterozygosity either at residue 57 of DQB1 or residue 52 of DQA1 was sufficient to abrogate statistical significance for disease association, although 43.6% of IDDM patients were included in these two groups as compared to 21.6% of normal controls. On the other hand the presence of two DQB1 alleles with aspartic acid in position 57 was sufficient to confer resistance to disease irrespective of the DQA1 genotype. Based on the number of possible susceptible heterodimers an individual can form, it was found that 85% of IDDM cases could form two or more heterodimers (two in cis and two in trans), but no IDDM case was found to form one susceptible heterodimer in cis. These results demonstrate that the complete HLA-DQ genotype, more than single DQB1 or DQA1 alleles or DQB1-DQA1 haplotypes, is associated with the highest risk of disease. Screening of the population for preventive purposes and/or early signs of IDDM should then take advantage of this result and "susceptible homozygous" individuals should be followed very closely and considered the first group of choice for possible new therapeutical trials.

Detection of BCR/ABL transcripts in chronic myeloid leukaemia by polymerase chain reaction and DNA enzyme immunoassay: a DNA probe assay without DNA labelling.

The detection of the t(9;22) translocation, typical of chronic myeloid leukaemia (CML), can be accomplished by cytogenetical detection of Philadelphia (Ph1) chromosome or by molecular analysis of the bcr/abl fusion gene with nucleic acid probes after amplification by polymerase chain reaction (PCR). PCR-based approaches are now widely used for follow up of CML patients during therapy or after bone marrow transplantation (BMT). We describe here a microtitre, colorimetric assay (DNA Enzyme Immunoassay, DEIA) for analysis of t(9;22) translocation after enzymatical amplification of RNA from CML patients. This assay is based on the use of a monoclonal antibody specifically reacting with double stranded DNA, i.e. with hybridized DNA. The assay represents a nonisotopic alternative to other current hybridization assays and requires no modifications of primers, probe or target DNA.

HLA-DQB1 typing of north east Italian IDDM patients using amplified DNA, oligonucleotide probes and a rapid DNA-enzyme immunoassay (DEIA).

We report on HLA-DQB1 typing in IDDM patients of north east Italian region using an enzymatic method based on the detection of hybridization reaction between PCR amplified DNA from whole blood and allele specific oligonucleotides by an antibody directed against double stranded DNA (DNA-enzyme immunoassay or DEIA). The method is reliable, simple and sensitive as the classical radioactive method with the advantage of using a universal non radioactive detection reagent. Nineteen families, each including one subject with juvenile insulin-dependent diabetes mellitus (IDDM) were analyzed. A strong association between absence of an aspartic acid (Asp) in position 57 of DQB1 beta chain in homozygous conditions and susceptibility to IDDM was found. In contrast with some previous observations, however, no significant association was found between Asp/non-Asp heterozygous genotype and IDDM. No patients were found with an homozygous Asp/Asp genotype, known to be protective in caucasoid population. Of particular interest was the DQB1 allelic distribution in our population sample. The non-Asp allele most frequently found in IDDM subjects was the DQB1 0201 allele and this finding was statistically significant (Pc value < 0.05, relative risk = 5.01). No significant association was found for any other allele including the DQB1 0302 (Pc value = not significant although with relative risk = 3.28) previously reported as the most frequent allele in IDDM caucasoid patients.