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K Vermaelen

Publications and source records attributed to K Vermaelen.

15 recordsLinked to original sources
PubMed1999

Allergen-induced changes in bone-marrow progenitor and airway dendritic cells in sensitized rats.

Eosinophilic airway inflammation is orchestrated by T-helper (Th)-2 lymphocytes. We have previously demonstrated that dendritic cells (DC) are essential for the presentation of antigen to these Th2 cells leading to airway inflammation. Here, we have examined the presence of DC in the lungs, the kinetics of appearance, and the possible involvement of the bone-marrow progenitor for DC in a rat model of ovalbumin (OVA)-induced airway inflammation. Sensitized rats were exposed to 0, 1, 3, or 7 consecutive daily OVA aerosols. Control rats were sham sensitized and/or exposed to phosphate-buffered saline (PBS), and bronchoalveolar lavage (BAL) was performed 24 h after the last challenge. DC were identified in BAL fluid as low-density, low-autofluorescence, CD3(-), CD45RA-, OX62(+), OX6(+) cells that had long surface extensions and strong costimulatory activity. Low but detectable amounts of BAL DC were seen in sensitized, unexposed animals. After three OVA exposures, the inflammatory infiltrate consisted of CD4(+)-activated T cells, eosinophils, and monocytes. The number of BAL DC was significantly increased in OVA-sensitized/OVA-exposed animals compared with sham-sensitized or PBS-exposed animals. The kinetics of DC increase closely parallelled those in other inflammatory cells. Bone-marrow cells taken from the OVA-sensitized and -exposed group were grown in the DC growth factor granulocyte macrophage colony-stimulating factor for 6 d and the yield of OX62(+)OX6(+) DC was 60% higher compared with PBS-exposed or sham-sensitized animals. We conclude that allergen exposition in sensitized rats increases the number of DC in the airways and the production of progenitors for DC in the bone marrow.

Animals↗
PubMed1987

11q-chromosome is associated with abnormal iron stores in myelodysplastic syndromes.

Nine cases of myelodysplastic syndrome with a deletion of the long arm of chromosome #11 (11q-) showed ringed sideroblasts, and three of which had an acquired sideroblastic anemia according to the criteria of the FAB classification. In contrast, among four cases of myelodysplastic syndromes with translocation of extra material to the long arm of chromosome #11 (11q+), only one showed bone marrow sideroblasts. These results strongly indicate that an 11q- chromosome is a marker of iron overload in myelodysplastic syndromes. Within the cases of 11q- associated with sideroblastosis, two cytogenetically different anomalies (i.e., terminal or interstitial deletions) were delineated.

Adult↗
PubMed1985

The 5q-anomaly.

A deletion of the long arm of chromosome #5 (5q-) occurs nonrandomly in human malignancies. As a rule, the deletion is interstitial; the distal breakpoint by conventional techniques is usually in band q32, the proximal breakpoints in q12 or q14. Variant breakpoints occur in less than 10% of all cases. As the sole anomaly, 5q- is characteristically found in refractory anemia with or without excess of blasts. It can occur as the sole anomaly in de novo or secondary acute nonlymphocytic leukemia, but is usually accompanied in those disorders by other chromosome changes that are also nonrandomly distributed. In addition, it can be found in lymphoproliferative disorders, and occasionally, also in solid tumors. The 5q- myelodysplastic syndrome typically occurs in older age groups, particularly in females. Characteristic features are macrocytic anemia, normal or elevated platelets in the presence of megakaryocytic anomalies, and a mild clinical course. In cases with 5q- only, transformation into ANLL occurs rarely. Additional chromosome anomalies and male sex are prognostically unfavorable signs. Sex ratio is also at the disadvantage of females in de novo 5q- ANLL, and the latter disorder can occur without being preceded by a myelodysplastic phase. A myelodysplastic phase usually precedes 5q- secondary leukemia, in males as well as in females, and additional chromosome anomalies, especially of chromosome #7, are almost invariably present in those cases. We conclude that 5q- is the most frequently occurring single chromosome anomaly in secondary leukemia. Furthermore, the resemblance between de novo and secondary 5q- MDS and ANLL is striking; clinically, as well as cytogenetically, they are indistinguishable, suggesting that all de novo cases may be due to environmental (chemical) carcinogens. Response to treatment and prognosis are very poor with current therapeutic regimens in de novo as well as in secondary 5q- ANLL. Morphologically, these ANLLs fall into all FAB categories. There is considerable evidence to show that the 5q- anomaly occurs in a myeloid precursor stem cell. The occasional occurrence in lymphoid malignancies, of B cell as well as T cell type, suggests that, as in Ph-positive disorders, a common progenitor stem cell may be affected in 5q- also. The 5q- lymphoid malignancies, however, are much more rare; it is not clear at the present time whether or not a 5q- counterpart of Ph-positive ALL exists, and mixed lymphoid-myeloid 5q- disorders have not yet been documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

Translocation t(8;10)(q12;p14) in lymphoproliferative disorders.

Cytogenetic studies were performed in two patients with a B-cell lymphoproliferative disease in progressive phase characterized by leukocytosis and important splenomegaly. In both patients an identical chromosome marker derived from a t(8;10)(q12;p14) translocation was found. This chromosome anomaly was associated with other abnormalities characteristic for lymphoid malignancies, i.e. a structural rearrangement of the long arm of chromosome 11 and a 14q+ in both patients. This new t(8;10) translocation may be a marker of accelerated phase in lymphoid disorders.

Aged↗
PubMed1984

High incidence of chromosome abnormalities in IgG3 myeloma.

Chromosomes were studied in 33 untreated myeloma patients, and results were correlated with the class of Ig secreted by the myeloma cells. A high incidence of clonal karyotypic anomalies seemed to be present in IgG3 myeloma patients, in whom the disease was advanced at diagnosis and rapidly progressing. Among the chromosome anomalies, the t(11;14)(q14;q32) was particularly prominent, and this chromosome anomaly, in analogy with the Ph1 chromosome, may characterize a family of lymphoproliferative disorders.

Adult↗
PubMed1984

Indirect stimulation of B-cell proliferation in vitro by T cells, as evidenced by cytogenetic analysis of PHA-stimulated cell cultures of B-cell lymphomas.

In a retrospective study of non-Hodgkin's lymphomas, the 14q+ marker was found in at least one of the samples examined from 17 patients with B-cell lymphoproliferative diseases (LPD). In the PHA-stimulated cultures, the marker was found in each sample in 10%-100% of the cells. An indirect stimulation, as indicated by a 3H-thymidine incorporation and IG secretion, of normal B cells by a T-cell mitogen, such as PHA, has been recently documented. This phenomenon is confirmed by our chromosome analysis, which demonstrated characteristic chromosome changes in PHA-stimulated cultures of patients with B-cell malignancies and indicated that the phenomenon can be observed not only in normal B cells but also in malignant B cells.

B-Lymphocytes↗
PubMed1984

Interstitial 9q- deletions in hematologic malignancies.

Sixteen patients with interstitial deletions of the long arm of chromosome #9 (9q-). were studied. From our observations and the findings of ten other cases in the literature, it can be deduced that the anomaly is almost exclusively found in myeloproliferative disorders and that it rarely occurs as the sole anomaly; however, in more than one-third of the cases, it was associated with a t(8;21) and occurred as a secondary event. The deletion appears to be interstitial, the breakpoints are somewhat variable, and the region carrying the abl oncogene was never involved.

Acute Disease↗
PubMed1984

Preliminary data on the in vitro proliferation pattern and karyotypic characteristics in cells of patients with ANLL.

Preliminary results of an in vitro study of the proliferation characteristics and karyotypes in the cells of a series of 20 patients with ANLL are presented. The leukemic cells exhibited in vitro proliferation patterns of essentially three types, all of which were very different from the proliferation pattern of normal bone marrow. Correlation with the karyotypic findings did not confirm that the cell cycle may be longer in aneuploid cells. To the contrary, a substantial part of the ANLL presented a karyotype that was normal by routine banding technique standards, in spite of the presence of a strikingly abnormal proliferation pattern of the dividing cells. These observations are important for a better understanding of the significance of chromosome anomalies in the development of leukemia, as well as for the clinician who, in the absence of chromosome markers, may use the proliferation pattern in the monitoring of leukemic patients.

Acute Disease↗
PubMed1983

5q- anomaly in a patient with disseminated teratoma.

A 5q- anomaly associated with other chromosome anomalies was found in the infiltrated bone marrow of a patient with a highly malignant teratoma originally located in the mediastinum. There was no evidence of a second malignancy, and it is likely that the 5q- anomaly was, indeed, associated with the malignant teratoma cells.

Adult↗
PubMed1983

Pentasomy 21 characterizing spontaneously regressing congenital acute leukemia.

Pentasomy 21 was found to characterize the proliferating cells in a case of transient congenital acute leukemia (or congenital acute leukemia) with spontaneous remission. The patient was phenotypically normal, and cytogenetically no evidence could be found for the existence of a mosaic with a normal cell line and one with more than two No 21 chromosomes. The importance of these findings is discussed.

Acute Disease↗
PubMed1983

Anomalies of the long arm of chromosome 11 in human myelo- and lymphoproliferative disorders. I. Acute nonlymphocytic leukemia.

In a series of 365 consecutive ANLL cases of which 45.1% had abnormal karyotypes, 13 cases were detected with a structural abnormality of the long arm of chromosome 11. Besides one isochromosome 11q, there were six deletions and six translocations. Of these 12 patients, seven had acute monocytic leukemia (FAB-type M5), two had an M4, two had an M2, and one case of secondary leukemia had an M3-like disorder. Similar results with regard to the type of leukemia were obtained upon analysis of 41 cases of ANLL with an 11q anomaly described in the literature. This study confirms that a high proportion of acute monocytic leukemias and a lesser proportion of acute myelomonocytic leukemias are characterized by an 11q anomaly, mostly involving bands q22 and/or q23. Acute monocytic leukemia with an 11q structural anomaly appears to have a poor prognosis.

Acute Disease↗
PubMed1983

3q-, 3q+ anomaly in malignant proliferations in humans.

Anomalies of both No. 3 chromosomes, of the t(3q-; 3q+) type can be observed in human malignancy as reported previously. It is our experience that this anomaly is found predominantly in myeloproliferative disorders, as a rather rare event, though occurring more frequently than similar exchanges between other homologous chromosomes. Previous claims about a relationship between this anomaly and thrombocytosis could not be confirmed, but the features found in a few patients indicate that further research should be undertaken to clarify this point.

Adult↗