We studied the genetic pattern of inheritance of the ratio between circulating CD4+ and CD8+ T lymphocytes in a population of healthy donors. The distribution of the CD4/CD8 ratio in males and females was significantly different and was significantly affected by age. In 46 randomly selected families, the parental CD4/CD8 ratio significantly influenced the ratio in offspring. Complex segregation analysis of the data rejected the non-genetic hypothesis; among the genetic models tested, a major recessive gene with a polygenic component and random environmental effects was the most parsimonious model. These findings indicate that the ratio of CD4+ and CD8+ T cells is genetically controlled in humans.

The recent identification of major genomic rearrangements in breast and breast/ovarian cancer families has widened the mutational spectrum of the BRCA1 gene, thus increasing the number of informative patients who can benefit from molecular screening. Numerous types of alterations have been identified in different populations with variable frequencies, probably due to both ethnic diversity and the technical approach employed. In fact, although several methods have been successfully used to detect large genomic deletions and insertions, most are laborious, time-consuming, and of variable sensitivity. In order to estimate the contribution of BRCA1 genomic rearrangements to breast/ovarian cancer predisposition in Italian families, we applied, for the first time as a diagnostic tool, the recently described multiplex ligation-dependent probe amplification (MLPA) methodology. Among the 37 hereditary breast/ovarian cancer (HBOC) families selected, all had a high prior probability of BRCA1 mutation, and 15 were previously shown to carry a mutation in either the BRCA2 (five families) or BRCA1 gene (10 families, including one genomic rearrangement). The application of BRCA1-MLPA to the remaining 22 uninformative families allowed the identification of five additional genomic rearrangements. Moreover, we observed that loss of constitutive heterozygosity of polymorphic markers in linkage disequilibrium is predictive of such BRCA1 alterations. By means of this approach, we demonstrate that BRCA1 genomic deletions account for more than one-third (6/15) of the pathogenic BRCA1 mutations in our series. We therefore propose to systematically include MLPA in the BRCA1 mutational analysis of breast/ovarian cancer families.

The X region of the HTLV-I genome contains four major open reading frames (ORFs), two of which, termed x-I and x-II, are of still unde®ned biological signi®cance. By indirect immuno¯uorescence and dual labeling with marker proteins, we demonstrate that p13 II , an 87-amino acid protein coded by the x-II ORF, is selectively targeted to mitochondria. Mutational analysis revealed that mitochondrial targeting of p13 II is directed by an atypical 10-amino acid signal sequence that is not cleaved upon import and is able to target the Green Fluorescent Protein to mitochondria. Expression of p13 II results in speci®c alterations of mitochondrial morphology and distribution from a typical string-like, dispersed network to round-shaped clusters, suggesting that p13 II might interfere with processes relying on an intact mitochondrial architecture. Functional studies of mitochondria with the cationic¯uorochrome tetramethylrhodamine revealed that a subpopulation of the cells with p13 II -positive mitochondria show a disruption in the mitochondrial inner membrane potential (Dc), an early event observed in cells committed to apoptosis. Taken together, these results suggest novel virus-cell interactions that might be important in HTLV-I replication and/or pathogenicity.

IFNs are highly pleiotropic cytokines also endowed with marked antiangiogenic activity. In this study, the mRNA expression profiles of endothelial cells (EC) exposed in vitro to IFN-α, IFN-β, or IFN-γ were determined. We found that in HUVEC as well as in other EC types 175 genes were up-regulated (>2-fold increase) by IFNs, including genes involved in the host response to RNA viruses, inflammation, and apoptosis. Interestingly, 41 genes showed a >5-fold higher induction by IFN-α in EC compared with human fibroblasts; among them, the gene encoding the angiostatic chemokine CXCL11 was selectively induced by IFN-α in EC along with other genes associated with angiogenesis regulation, including CXCL10, TRAIL, and guanylate-binding protein 1. These transcriptional changes were confirmed and extended by quantitative PCR analysis and ELISA; whereas IFN-α and IFN-β exerted virtually identical effects on transcriptome modulation, a differential gene regulation by type I and type II IFN emerged, especially as far as quantitative aspects were concerned. In vivo, IFN-α-producing tumors overexpressed murine CXCL10 and CXCL11, guanylate-binding protein 1, and TRAIL, with evidence of CXCL11 production by tumor-associated EC. Overall, these findings improve our understanding of the antiangiogenic effects of IFNs by showing that these cytokines trigger an antiangiogenic transcriptional program in EC. Moreover, we suggest that quantitative differences in the magnitude of the transcriptional activation of IFN-responsive genes could form the basis for cell-specific transcriptional signatures.

Human T-cell leukemia virus type 1 encodes a number of "accessory" proteins of unclear function; one of these proteins, p13 II , is targeted to mitochondria and disrupts mitochondrial morphology. The present study was undertaken to unravel the function of p13 II through (i) determination of its submitochondrial localization and sequences required to alter mitochondrial morphology and (ii) an assessment of the biophysical and biological properties of synthetic peptides spanning residues 9 -41 (p13 9 -41 ), which include the amphipathic mitochondrialtargeting sequence of the protein. p13 9 -41 folded into an ␣ helix in micellar environments. Fractionation and immunogold labeling indicated that full-length p13 II accumulates in the inner mitochondrial membrane. p13 9 -41 induced energy-dependent swelling of isolated mitochondria by increasing inner membrane permeability to small cations (Na ؉ , K ؉ ) and released Ca 2؉ from Ca 2؉ -preloaded mitochondria. These effects as well as the ability of full-length p13 II to alter mitochondrial morphology in cells required the presence of four arginines, forming the charged face of the targeting signal. The mitochondrial effects of p13 9 -41 were insensitive to cyclosporin A, suggesting that full-length p13 II might alter mitochondrial permeability through a permeability transition pore-independent mechanism, thus distinguishing it from the mitochondrial proteins Vpr and X of human immunodeficiency virus type 1 and hepatitis B virus, respectively.HTLV-1 1 is a complex retrovirus that is associated with two distinct pathologies, a leukemia/lymphoma of mature CD4 ϩ