Microsatellite instability is associated with the histological features of the tumor in nonfamilial colorectal cancer.

Replication errors (RERs) at microsatellite loci were examined in 46 specimens of nonfamilial colorectal cancer. Somatic microsatellite alterations in at least two genetic loci, D11S904, D13S175, D2S123, and D10S197, consistent with a RER(+) phenotype were found in four cases (8.7%). Six additional cases (13%) showed alterations at a single locus. Mucinous differentiation was observed in 3 of 4 (75%) adenocarcinomas with a RER(+) phenotype and only in 19% (8 of 42) of RER(-) adenocarcinomas (P < 0.05). A distinct cap of inflammatory cells at the advancing edge of the tumor and Crohn's-like reaction in peritumoral stroma were histologically identified in 50 and 25% of RER(+) and in 5 and 0% of RER(-) tumors, respectively (P < 0.05). Also, the plexiform pattern of growth of carcinoma turned out to be significantly associated with the RER(+) phenotype (P < 0.05). Mucinous differentiation and stromal inflammatory reactions are frequent features of hereditary nonpolyposis colorectal cancer in which germ-line mutations of mismatch repair genes cause genetic instability. Our results indicate that a link exists between such histological features and somatic genetic instability consistent with a RER(+) phenotype also in nonfamilial colorectal cancer.

ALL-1 gene rearrangements in acute myeloid leukemia: association with M4-M5 French-American-British classification subtypes and young age.

We have analyzed by Southern blotting the ALL-1 (MLL, HRX, Hrtx 1) gene configuration in a series of 126 patients with acute myeloid leukemia (AML) representative of all ages and French-American-British Classification groups and correlated this genetic feature with clinical and biological features at diagnosis. ALL-1 gene rearrangements were detected in 17 of the 74 cases with M4-M5 (myelomonocytic and monocytic) AML and in 2 of the 52 cases with other leukemic subtypes (P < 0.01). Within the series of 74 M4-M5 patients, ALL-1 rearrangements were significantly associated with French-American-British Classification M5 (P = 0.009), high WBC (P = 0.002), and young age. In particular, all 5 infant (< 1.5 years) AML cases, 6 of the 19 (31%) patients between 1.5 and 18 years of age, and 6 of the 50 (12%) patients > 18 years old showed an altered ALL-1 genomic configuration (P < 0.001). Immunophenotypic characterization revealed coexpression of lymphoid and myeloid markers in 6 of 17 ALL-1 rearranged M4-M5 cases. The IgH gene configuration was studied in 77 of 126 AMLs. Five patients (6%) showed IgH clonal rearrangements and all were in the ALL-1 rearranged group (P < 0.0001). Our findings indicate that ALL-1 rearrangement is the commonest genetic alteration presently detectable in M4-M5 AML, particularly in childhood where it is found in up to one-third of all cases. The association of IgH rearrangements with ALL-1 alterations in AML, coupled to the frequent detection in this subset of lymphoid associated markers, further supports the origin of these tumors from a common multipotent precursor with bipotential lymphoid and monocytic differentiation capability.

Simultaneous expression of RBTN-2 and BCR-ABL oncogenes in a T-ALL with a t(11;14)(p13;q11) and a late-appearing Philadelphia chromosome.

Cytogenetic analysis of a pediatric patient with T-cell acute lymphoblastic leukemia (T-ALL) revealed a mosaic karyotype, 47,XX,+17,t(11;14)(p13;q11)/47,XX,+17,t(9;22)(q34;q11),t(11;14) (p13;q11). DNA blot analysis was used to examine the break-point within the BCR gene on chromosome 22 and showed that the breakpoint occurred within the 20-kb minor breakpoint cluster region (m-bcr) located within the first intron of the BCR gene. Immunoprecipitation analysis demonstrated that the leukemic cells expressed the P185 BCR-ABL protein tyrosine kinase. P185 BCR-ABL has previously been shown to be expressed in most cases of Ph+ acute leukemia of myeloid and B-progenitor origin. Here, we demonstrate for the first time that P185 can also be expressed in the T-cell lineage. DNA blot hybridization was also used to characterize the t(11;14) translocation. This showed rearrangement on chromosome 11 within the T-ALLbcr region, upstream of the RBTN-2 gene. Polymerase chain reaction revealed the presence of RBTN-2 transcripts in the leukemic cells. Finally, comparison of the T-ALLbcr, BCR-ABL, IGH, TCR beta and gamma gene rearrangements in leukemic cells obtained at the time of diagnosis and at first relapse showed that relapse occurred in a leukemic clone indistinguishable from the major Ph+ clone involved at diagnosis. Together, these data support a multistep pathogenesis in which the Philadelphia (Ph) chromosome translocation appeared subsequent to the +17 and t(11;14) and imparted a growth advantage over the Ph-negative cells that carried these abnormalities.

Allogeneic hemopoietic stem cell transplantation in solid tumors.

The existence of a graft versus tumor (GVT) effect of donor-derived T cells after allogeneic hematopoietic stem cell transplantation is well established as a critical component for the success of the procedure in several hematologic malignancies. Although it has been suggested that a GVT effect might also be generated in patients affected by refractory solid tumors, the morbidity of conventional allogeneic hematopoietic stem cell transplantation has limited its investigation in these diseases. Recently introduced allogeneic nonmyeloablative regimens have greatly decreased morbidity and mortality related to transplants which retain a powerful GVT. On this basis, it has become possible to explore the existence of alloreactivity toward solid tumors. The present article reviews the early clinical results of this novel immunotherapeutic approach for solid tumors.

Response to intermediate and standard doses of IFN-beta in hairy-cell leukaemia.

Thirteen hairy-cell leukaemia patients were treated with IFN-beta (6 X 10(6) IU/m2) for 7 days, alternate weeks, for three cycles. IFN-beta was then continued at the same dose twice a week for 24 weeks. Treatment was discontinued in 2 non-responders and 2 partial responders (1 haem PR, 1 path PR) because of complications unrelated to IFN. The objective response in the nine patients who completed therapy was 66% (1 CR, 3 path PR and 2 haem PR); 2 patients achieved MR. Responses lasted from 5 to 45+ months. Four newly diagnosed patients and 3 in relapse after discontinuation of IFN-beta therapy (6 X 10(6) IU/m2), were treated with a lower dose of IFN-beta (2 X 10(6) IU/m2). The objective response to this dose was 57% (3 path PR, 1 haem PR). Another patient obtained MR. No patient has relapsed 6-12 months after therapy discontinuation. IFN-beta was well tolerated, especially at the lower dose and no chronic toxicity was observed. Therefore IFN-beta may be suggested as an alternative treatment for HCL.

Interphase FISH for Y chromosome, VNTR polymorphisms, and RT-PCR for BCR-ABL in the monitoring of HLA-matched and mismatched transplants.

Thirty-six sex-mismatched transplants were studied using fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) methods. Molecular cytogenetics was performed using interphase FISH with a centromeric probe for chromosome Y, and PCR amplification was performed with a set of VNTR microsatellite loci. In addition, reverse transcriptase-PCR (RT-PCR) for BCR-ABL fusion was used to investigate cases of Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL). Our integrated approach of post-transplant monitoring was helpful in documenting successful transplants and in controlling the size of Ph-positive clones in CML. A striking overlap was found between results from FISH analysis and PCR for polymorphic loci.

Different mechanisms regulate the IFN-inducible expression of 40 kDa human 2'-5' oligo (A) synthetase in HeLa and Molt 4 cells.

Expression of 40 kDa 2'-5' oligo (A) synthetase can serve as a marker of interferon (IFN) activity on the biological target. The mechanisms of induction of human 40 kDa 2'-5' oligo (A) synthetase by IFNs were investigated in HeLa and Molt 4 cells. Using a combined treatment with cycloheximide and actinomycin D we observed that in HeLa cells IFN-alpha did not need ongoing protein synthesis to induce the enzyme, whereas the addition of cycloheximide prevented the induction by IFN-gamma. IFN-alpha induced the 40 kD enzyme in the T-cell line Molt 4 to a level comparable to that in HeLa cells, but only in the presence of active protein synthesis. These results suggest that an early response gene coding for a positive IFN-inducible protein may be needed in T cells, but not in HeLa cells to regulate the transcription of this 2'-5' oligo (A) synthetase gene.

Bone marrow stroma-dependent modulation of CD45R isoform expression on Abelson virus transformed pre-B cells.

The CD45 glycoprotein family exhibits cell-lineage-associated structural heterogeneity which is due, in part, to alternative pre-mRNA splicing. The Abelson murine leukemia (A-MuLV) preferentially transforms immature B cells that express a B-cell-specific high molecular weight CD45 isoform, called B220. However, we observed that A-MuLV-transformed cell lines are often B220- while maintaining high levels of "pan" CD45 expression. In vitro transformation of murine bone marrow revealed that the stromal microenvironment over which A-MuLV-transformed lymphoblasts are grown affected the B220 phenotype of the pre-B cells. Over a period of a few weeks, B220+ populations grown over a clonal stromal cell line gradually became B220-. However, the transition from a B220+ to B220- phenotype was dependent on the lot of fetal calf serum used. In contrast, cells grown over a heterogeneous bone marrow stroma maintained B220+ expression for long periods of time. The appearance of B220- cells in clonal B220+ populations indicated that the change in phenotype resulted in part from modulation of B220 expression. B220- B-cell lines did not express the high molecular weight CD45 RNA species indicating that the B220- phenotype was due to alternative pre-mRNA splicing. Finally, the shift from B220+ to B220- was not accompanied by changes in the stage of development of the cultures. These observations demonstrate that expression of B220 is not required for the continued proliferation of Abelson-transformed pre-B cells and is regulated by unknown environmental factors.

Simultaneous demonstration of the Philadelphia chromosome in T, B, and myeloid cells.

A patient presented with lymphoblastic lymphoma in lymph-nodes and chronic myelogenous leukemia (CML) in narrow and peripheral blood. All marrow and unstimulated peripheral blood cells contained the Philadelphia chromosome[t(9:22)]. Lymphoma cells were analyzed by flow cytometry and were identified as T cells (CD2+CD5+CD7+CD34+). All fresh lymphoma cells contained the t(9:22) translocation. Cultures of purified peripheral blood T and B cells and specifically stimulated NK cells revealed that 59% of the B cells, 10% of the NK cells, and none of the normal T cells contained the translocation. The lack of translocation in normal peripheral T cells is attributed to their long lifespan. No rearrangement of immunoglobulin or T cell receptor beta or gamma genes was found in either the leukemia or lymphoma cells. Analysis of the DNA from cryopreserved lymphoma biopsy showed clonal rearrangement within the common breakpoint cluster region of the bcr gene identical to the bcr rearrangement in DNA from leukemia blood cells. The data support the concept that T and B cells originate in the patient's totipotent stem cell from which the CML is also derived.

BCR-ABL and v-abl oncogenes induce distinct patterns of thymic lymphoma involving different lymphocyte subsets.

The human BCR-ABL oncogenes encoded by the Philadelphia chromosome (Ph) affect the pathogenesis of diverse types of leukemia and yet are rarely associated with T-lymphoid leukemia. To determine whether BCR-ABL kinases are inefficient in transforming T lymphocytes, BCR-ABL-expressing retroviruses were injected intrathymically into mice. Thymomas that expressed BCR-ABL kinase developed after a relatively long latent period. In most thymomas, deletion of 3' proviral sequences resulted in loss of tk-neo and occasionally caused expression of kinase-active carboxy-terminally truncated BCR-ABL oncoprotein. In contrast, deletion of 3' proviral sequences was not observed in thymomas induced with Abelson murine leukemia virus (A-MuLV). BCR-ABL viruses induced distinct patterns of disease and involved different thymocyte subsets than A-MuLV and Moloney murine leukemia virus (Mo-MuLV). While Mo-MuLV only induced Thy-1+ thymomas, v-abl- and BCR-ABL-induced thymomas often contained mixed populations of B220+ and Thy-1+ lymphocytes in the same tumor. In most v-abl and BCR-ABL tumors, Thy-1+ lymphoid cells expressed CD8 and a continuum of CD4 ranging from negative to positive. Conversely, Mo-MuLV thymomas contained distinct populations of CD4+ cells that were either CD8+ or CD8-. A-MuLV-transformed T-lymphoid cells did not express the CD3/T-cell receptor complex, while BCR-ABL tumors were CD3+. Thus, BCR-ABL viruses preferentially induce somewhat more differentiated T lymphocytes than are transformed by A-MuLV. Furthermore, rare B220+ lymphocytes may represent preferred v-abl and BCR-ABL transformation targets in the thymus.

Characterization of cytoplasmic and nuclear polypeptides induced by interferon-gamma in a murine pre-B cell leukemia.

The effects of interferon-gamma (IFN-gamma) on protein synthesis of a pre-B cell leukemia, L1210, have been studied by two-dimensional gel electrophoresis. In total cell extracts, at least ten proteins were induced de novo, or increased in their expression, after an 18-h IFN-gamma treatment, whereas in the nuclear extracts eight proteins were specifically induced. Of these, increased synthesis of a 40-kDa/pI 5.9 cytoplasmic protein was the most prominent and reproducible. Most of these proteins appear to be specific for a defined step of differentiation, since they are not found in other B cell leukemias upon IFN-gamma treatment. Others appear to be tissue specific, since they are not induced in fibroblasts nor in T cells. In addition, synthesis of some of the induced proteins appeared to require rapid transcription of new mRNA, because actinomycin D markedly inhibited their formation when added immediately before IFN-gamma. In keeping with this finding, in vitro translation of mRNA from IFN-gamma-treated L1210 cells into a rabbit reticulocyte lysate system, followed by analysis of the labeled proteins by two-dimensional gel electrophoresis, revealed the appearance of at least seven proteins. Taken as a whole, these results demonstrate that in leukemic pre-B cells IFN-gamma induces the transcriptional activation of genes coding for cytoplasmic and nuclear proteins, some of which could be employed as specific cell activation markers.

Bcl-6 protein expression in normal and neoplastic lymphoid tissues.

The human bcl-6 gene, which is rearranged in about 30% of diffuse large B-cell lymphomas (DLCL-B), encodes for a Kruppel-type zinc finger protein of 706 amino acids. In order to investigate the expression of the bcl-6 gene at the protein level, two monoclonal antibodies (PG-B6a and PG-B6p) directed against the human bcl-6 protein were generated by immunizing Balb/c mice with a recombinant protein corresponding to the amino-terminal region (amino acids 3-484) of bcl-6. PG-B6a (a = avian) recognized the most conserved bcl-6 epitope (expressed in many animal species, including avian). PG-B6p (p = paraffin) reacted with an epitope of bcl-6 partially resistant to fixatives and detectable on microwave-heated paraffin sections. At immunocytochemistry, bcl-6 localized in the nucleus with a microgranular or diffuse pattern. Strong nuclear expression of bcl-6 was mainly detected in normal germinal-center B-cells, whereas mantle- and marginal-zone B cells, as well as plasma cells and marrow B-cell precursors, did not express bcl-6. These immunohistological findings strongly suggest that bcl-6 may play a role as a regulator of germinal-center related functions. All MoAbs stained neoplastic cells of follicular lymphomas, DLCL-B, and Burkitt's lymphomas. In DLCL-B, bcl-6 expression was independent of bcl-6 gene rearrangements and did not correlate with expression of other markers or the proliferation index. Among low-grade B-cell lymphomas, immunostaining for bcl-6 proved useful for differentiating proliferation centers in B-CLL (bcl-2+/bcl-6-) from trapped germinal centers in mantle-cell lymphomas (bcl-2-/bcl-6+). Strong nuclear positivity for bcl-6 was consistently detected in tumor (L&H) cells of nodular, lymphocyte-predominant Hodgkin's disease (NLPHD). These results further support the concept that NLPHD is a histogenetically distinct (germinal-center derived) subtype of HD. Notably, the nuclei of reactive CD3+/ CD4+ T cells near to and rosetting around L&H cells in NLPHD were also strongly bcl-6+, but lacked CD40 ligand (CD40L) expression. This staining pattern clearly differed from that of classic HD, whose cellular background was made up of CD3+/CD4+ T cells showing the bcl-6-/CD40L+ phenotype. The above immunohistological findings suggest that (a) bcl-6 may play a role in regulating B-cell differentiation step(s) occurring within germinal centers; (b) deregulated bcl-6 expression caused by rearrangements may contribute to B-lymphomagenesis; (c) bcl-6 is possibly involved in the pathogenesis of NLPHD.

Detection of homozygous deletions of the cyclin-dependent kinase 4 inhibitor (p16) gene in acute lymphoblastic leukemia and association with adverse prognostic features.

A recently described putative tumor suppressor gene, the cyclin-dependent kinase 4 inhibitor (p16), has been shown to be altered by deletions and/or point mutations in various human cancers. To assess the incidence and clinico-biologic correlations of p16 homozygous deletion in hemopoietic tumors, we studied a panel of 244 DNA samples representative of distinct acute (99 cases) and chronic (57 cases) leukemia subtypes, myelodysplastic (22 cases) and myeloproliferative (15 cases) syndromes, and lymphomas (51 cases). A 361-bp probe complementary to the p16 exon 2 gene sequences was generated by polymerase chain reaction and used in Southern blot hybridization against these tumor DNAs. Homozygous deletions of p16 (p16-/-) were detected in 10 of 58 (17%) cases of acute lymphoblastic leukemia (ALL) of either B or T lineage and in no other tumors. Single-strand conformation polymorphism analysis of p16 exons 1 and 2 was also performed in 40 of the 58 ALL cases and in 16 lymphomas. In no cases were point mutations detected. The comparison of clinical features at presentation in p16-/- and in p16 germline ALL cases showed a greater leukemic cell mass (P = .001) and higher white blood cell counts (P = .01) in the former group. Two ALL cases in which diagnostic and relapse DNA samples were available showed p16-/- in both specimens. We conclude that homozygous p16 gene deletions characterize a subset of ALL with features of aggressive disease.

Role of T-helper type 2 cytokines in down-modulation of fas mRNA and receptor on the surface of activated CD4(+) T cells: molecular basis for the persistence of the allergic immune response.

The mechanisms responsible for persistence of T lymphocytes at the sites of allergic inflammation are not completely understood. Activated T cells, usually expressing Fas on their surface, undergo activation-induced apoptotic death, thus limiting the dangerous consequences of a persistent immune reaction. We have previously shown that pulmonary T lymphocytes from untreated asthmatic subjects do not express surface Fas receptors nor do they contain Fas mRNA, yet they display normal levels of Fas ligand. This is not an inherited defect and is confined to mucosal T cells. To gain insights into the mechanism responsible for these findings, we performed a set of experiments with both purified Dermatophagoides pteronyssinus allergen and recombinant human cytokines: interleukin 2 (IL-2), IL-4, IL-5, transforming growth factor beta1, interferon gamma, and granulocyte-macrophage colony-stimulating factor (GM-CSF). In vitro exposure of purified CD4(+) lymphocytes to allergen yielded only transient up-regulation of surface Fas but did not influence susceptibility to Fas-mediated cell death. T-helper type 2 cytokines (IL-4, IL-5, and GM-CSF) had a dose-dependent and specific inhibitory effect on Fas mRNA, suggesting a new fundamental biological role in the survival of inflammatory cells during allergen exposure.

Modulation of NK activity by thymic hormones: in vitro effects of thymostimulin.

Plastic-adherent depleted or not depleted peripheral mononuclear blood cells (PMBC) from healthy donors showed enhanced lytic activity against 51Cr-labelled K562 target cells when exposed to thymostimulin (TS), 1 microgram ml-1, for 3 h, washed and incubated in TS-free medium before testing for natural killer (NK) cytotoxicity. No modification of NK cell activity was seen when effector cells were treated with placebo (splenic extract). The NK boosting activity of TS was lost when effector cells were treated for 3 h immediately before the performance of the cytotoxic test or when this thymic extract was added directly to the mixture of effector and target cells during the lytic phase of 51Cr release assay.

Prenatal diagnosis of genetic abnormalities using fetal CD34+ stem cells in maternal circulation and evidence they do not affect diagnosis in later pregnancies.

In the present study, we report a new method for enrichment and analysis of fetal CD34+ stem cells after culture in order to determine whether it is feasible for noninvasive prenatal diagnosis. We also determined whether fetal CD34+ stem cells persist in maternal blood after delivery and assessed whether they have an impact on noninvasive prenatal diagnosis of genetic abnormalities. Peripheral blood samples were obtained from 35 pregnant women, 13 non-pregnant women who had given birth to male offsprings, 12 women who had never been pregnant, and eight pregnant women with male fetuses. CD34+ stem cells were enriched and either cultured for prenatal diagnosis or analyzed with fluorescence in situ hybridization (FISH)/polymerase chain reaction (PCR) to determine peristance in maternal blood. Fetal/maternal cells can be isolated and grown "in vitro" to provide enough cells for a more accurate fetal sex or aneuploid prediction than is provided by unenriched and uncultured CD34+ stem cells. The presence of fetal cells in maternal blood samples from mothers who had given birth to male offspring was found in 3 of 13 blood samples. PCR was positive for Y chromosome in one woman who had never been pregnant. Analysis of cultured CD34+ stem cells from mothers with Y PCR positivity did not detect any male cells in any samples. Even if PCR positivity is due to persistence of fetal stem cells from previous pregnancies, it does not seem to affect this new system of enrichment, culture, and FISH analysis of CD34+ fetal stem cells.

Selective purging by human interleukin-2 activated lymphocytes of bone marrows contaminated with a lymphoma line or autologous leukaemic cells.

The ability of recombinant interleukin 2 (rIL2) activated lymphocytes (LAK) to purge BM samples contaminated by tumour cells was evaluated. Human BM mononuclear cells were contaminated with 10% of the lymphoma line CA46 and then cultured in liquid medium containing 1000 U/ml of rIL2 and/or LAK autologous to the used BM. At the end of coculture the growth of residual tumour cells and of CFU-GM were evaluated by clonogenic assay. No tumour cell growth was observed in 5/5 independent experiments after 18 h of coculture with LAK. No significant inhibition of CFU-GM growth was also noted. Subsequently, the effect of LAK on BM obtained from four leukaemic patients and contaminated with 20-50% of their own AML and ALL cells was studied using MAb as a tool for identifying leukaemic cells. LAK eliminated 24-78% of contaminating cryopreserved uncultured autologous leukaemic cells. In five cases the BM was contaminated by a low (2%) amount of ALL cells. In these patients the monoclonal heavy chain rearrangement typical of ALL was no longer visible after coculture with LAK. Evidence for selective tumour cytotoxicity by LAK was confirmed by using autologous BM cells as hot and cold targets in a 51Cr release assay. Finally, successful haematologic reconstitution of lethally irradiated BALB/c mice was obtained using syngeneic BM cocultured with LAK. These results support the investigational use of rIL2 and LAK in the treatment of human leukaemia.

Biochemical and immunological responses of hairy cell leukemia patients to interferon beta.

Ten hairy-cell leukemia patients were treated with interferon beta (IFN-beta) at a dose rate of 2 x 10(6) IU/m2 x 5 days for 4 weeks (induction therapy) and, thereafter, at the same dose three times a week for 11 months (maintenance therapy). The effect of this treatment on serum neopterin, beta 2-microglobulin, (2'-5')oligoadenylate [(2'-5')An] levels, intracellular (2'-5')An values and human Mx protein synthesis was analysed. There were significant rises in serum neopterin and (2'-5')An levels during both induction and maintenance, whereas beta 2-microglobulin levels rose only during induction. Rises in intracellular (2'-5')An were documented mainly during induction, but they were not significantly higher than pretherapy values. IFN beta provoked an increase in human Mx protein synthesis over the entire induction-maintenance period, but was only significantly higher than baseline during induction. All markers proved useful for monitoring the effects of IFN beta dose schedules, but were not predictive of clinical outcome. Natural killer activity and IFN gamma production, which were initially defective, followed a different trend from that of the other factors studied, in that increases were documented only late in the course of therapy when the disease was already in remission.