No abstract

In order to develop a human immunodeficiency virus type 1 vaccine with global efficacy, it is important to evaluate the virus populations that are transmitted to individuals living in high-incidence areas. To determine the nature of the human immunodeficiency virus type 1 population transmitted to women during heterosexual contact, we examined the diversity of the proviral envelope gene in infected cells in both genital secretions and peripheral blood from six recently seroconverted Kenyan women. Heterogeneous virus populations were present in cervical secretions and/or peripheral blood shortly after seroconversion for five of six infected individuals, and tissue-specific variants were identified in several cases.

Clear cell sarcoma of soft tissue (CCS-ST) is a rare malignant neoplasm characterized by a tumor-defining translocation [t(12;22) (q13;q12)], resulting in the EWS-ATF1 gene fusion. An extremely limited number of visceral CCS-ST cases have been reported in the literature. Here the authors report a visceral CCS-ST in a Hispanic adolescent male with a large infiltrative mass involving the small bowel. The tumor was evaluated by light microscopy, immunocytochemistry, electron microscopy, cytogenetics, and molecular genetics. The tumor cells were strongly positive for S-100 protein, but negative for HMB-45. Rare premelanosomes were identified only after an extensive search with electron microscopy. Cytogenetics showed a characteristic t(12;22)(q13;q12) for CCS-ST with isochromosome 18q and trisomy 22. An EWS exon 8 sense primer and an antisense ATF1 primer were employed for detection of the CCS-ST tumor-defining EWS-ATF1 translocation, using reverse transcriptase-polymerase chain reaction techniques (RT-PCR), and the fusion gene breakpoint underwent DNA sequencing. This tumor is exceptional, because it is the first visceral CCS-ST that has been confirmed by RT-PCR and DNA sequencing. This case also illustrates the necessity of a multimodal approach to tumor diagnosis, and the utility of cytogenetics and molecular pathology in confirming the diagnosis of CCS-ST and eliminating conventional metastatic or primary visceral malignant melanoma as a consideration.

Transforming growth factor (TGF)-beta, a pleiotropic cytokine that regulates cell growth, is secreted by many human tumors and markedly inhibits tumor-specific cellular immunity. It has previously been shown by our group that transduction of cytotoxic T lymphocytes (CTLs) with a retroviral vector expressing the dominant-negative TGFbeta type II receptor (DNR) overcomes this tumor evasion in a model of Epstein-Barr virus (EBV)-positive Hodgkin disease. TGFbeta is an important physiologic regulator of T-cell growth and survival, however, abrogation of this regulatory signal in genetically modified cells is potentially problematic. To ensure that unresponsiveness to TGFbeta did not lead to the unregulated growth of genetically modified CTLs, the characteristics of DNR-transduced CTLs in vivo were studied. Donor C57BL6 mice were vaccinated with human papillomavirus-E7 plasmid DNA to induce production of E7-specific CTLs. The E7-specific CTLs were genetically modified to express enhanced green fluorescent protein (GFP) or DNR and administered to syngeneic mice. All mice received monthly boosts with E7 DNA for 9 months, and during this time, transduced CTLs were detected in the peripheral blood of most of the mice using a quantitative real-time polymerase chain reaction. By 12 months, 3 months after cessation of vaccination, no DNR-transduced CTLs or GFP-transduced CTLs were detected in the peripheral blood. There were 4 cases of lymphoma (2 DNR-transduced mice and 2 control mice): all tumors were CD3-/CD8- and were also negative for the DNR transgene. Hence, mature antigen-specific cytotoxic T cells can be genetically modified to resist the antiproliferative effects of TGFbeta without undergoing spontaneous lymphoproliferation in vivo. They may be of value for treating human cancers, which use TGFbeta as a powerful immune evasion mechanism.