Differential Ligand Binding to a Human Cytomegalovirus Chemokine Receptor Determines Cell Type–Specific Motility

While most chemokine receptors fail to cross the chemokine class boundary with respect to the ligands that they bind, the human cytomegalovirus (HCMV)-encoded chemokine receptor US28 binds multiple CC-chemokines and the CX3C-chemokine Fractalkine. US28 binding to CC-chemokines is both necessary and sufficient to induce vascular smooth muscle cell (SMC) migration in response to HCMV infection. However, the function of Fractalkine binding to US28 is unknown. In this report, we demonstrate that Fractalkine binding to US28 not only induces migration of macrophages but also acts to inhibit RANTES-mediated SMC migration. Similarly, RANTES inhibits Fractalkine-mediated US28 migration in macrophages. While US28 binding of both RANTES and Fractalkine activate FAK and ERK-1/2, RANTES signals through Gα12 and Fractalkine through Gαq. These findings represent the first example of differential chemotactic signaling via a multiple chemokine family binding receptor that results in migration of two different cell types. Additionally, the demonstration that US28-mediated chemotaxis is both ligand-specific and cell type–specific has important implications in the role of US28 in HCMV pathogenesis

Abberant cytogenetic evolution pattern of Philadelphia-positive chronic myeloid leukemia treated with interferon-alpha

The cytogenetic evolution of 32 Philadelphia (Ph)-positive chronic myeloid leukemias (CML) receiving interferon-alpha (IFN-alpha) therapy was compared to the patterns in untreated CML and cases treated with busulfan (Bu), hydroxyurea (Hy), and allogeneic bone marrow transplantation (BMT). Half of the CML receiving IFN-alpha had at least one of the well-known major or minor route aberrations whereas 16 cases displayed unusual secondary abnormalities, of which only del(7p) and del(13q) were recurrent; a frequency significantly higher than in CML without therapy or after Bu and Hy treatment (P < 0.001) but similar to the one found post-BMT. The incidence of cases with cytogenetically divergent subclones, ie cell populations with unrelated aberrations in addition to the t(9;22), was also higher in the IFN-alpha group compared to the untreated, Bu and Hy groups (P < 0.01) but similar to the post-BMT group. Finally, 14 of the 32 IFN-alpha-treated CML displayed cytogenetic evolution already during the chronic phase; again a higher incidence than in the untreated, Bu and Hy groups (P < 0.001) but not different from the post-BMT group. These findings strongly indicate that IFN-alpha, directly or indirectly, can induce clones with aberrant chromosomal evolution patterns to evolve and proliferate, but the mechanisms underlying these cytogenetic peculiarities remain to be elucidated

Cytogenetic pattern in leukemic cells of patiens with constitutional chromosome anomalies.

Acquired karyotypic changes analyzed by banding techniques in 21 patients with a malignant hematologic disorder and a major constitutional chromosome anomaly, including ten patients with trisomy 21, five patients with a balanced translocation, and six patients with a sex chromosome anomaly. Detailed karyotypic findings were ascertained in 28 additional patients reported in the literature. Some striking differences were observed in the combined material of the present series and cases previously published as regards (a) distribution of morphological leukemia types among patients with different types of constitutional anomalies, and (b) incidence and type of acquired chromosomal abnormality among patients with different types of constitutional anomalies