Lack of disease in long-term nonprogressors with human immunodeficiency virus type 1 (HIV-1) infection was strongly associated with very low copy numbers of HIV-1 DNA and RNA in peripheral blood mononuclear cells and plasma and the presence of high levels of anti-HIV-1 CD8 ؉ memory cytotoxic T lymphocytes specific for Gag, Pol, and Env, compared with levels present in intermediate and advanced progressors. CD8 ؉ memory cytotoxic T lymphocytes may have an important role in controlling HIV-1 replication and preventing disease in long-term nonprogressors.

CD4 T cell responses were studied for >2 years in 27 zidovudine-experienced patients with advanced human immunodeficiency virus type 1 (HIV-1) infection who received triple combination drug therapy with indinavir, zidovudine and lamivudine or zidovudine plus lamivudine or zidovudine alone for 24-42 weeks before switching to the three-drug therapy. Subjects initially given the three drugs had viremia suppressed to undetectable levels and increases in T cell proliferative and cytokine responses to microbial antigens through 2 years of follow-up. Patients receiving the triple-drug therapy after either indinavir or zidovudine-lamivudine treatment had similar increases in T cell responses only if they also had suppression of virus load. CD4 T cell reactivity to HIV-1 antigens was not restored. Prolonged indinavir-zidovudine-lamivudine treatment has significant but incomplete enhancing effects on CD4 T cell reactivity, which could be important in host control of microbial and persistent HIV-1 infections.

T-cell responses to X4 strains of human immunodeficiency virus type 1 (HIV-1) are considered important in controlling progression of HIV-1 infection. We investigated the ability of dendritic cells (DC) and various forms of HIV-1 X4 antigen to induce anti-HIV-1 T-cell responses in autologous peripheral blood mononuclear cells from HIV-1-infected persons. Immature DC loaded with HIV-1 IIIB-infected, autologous, apoptotic CD8− cells and matured with CD40 ligand induced gamma interferon production in autologous CD8+ and CD4+ T cells. In contrast, mature DC loaded with HIV-1 IIIB-infected, necrotic cells or directly infected with cell-free HIV-1 IIIB were poorly immunogenic. Thus, HIV-1-infected cells undergoing apoptosis serve as a rich source of X4 antigen for CD8+ and CD4+ T cells by DC. This may be an important mechanism of HIV-1 immunogenicity and provides a strategy for immunotherapy of HIV-1-infected patients on combination antiretroviral therapy

Alkaloids with allelopathic activity are not as well-known as other allelochemicals. Our study revealed that total alkaloids from seeds of the medicinal plant Peganum harmala L. possessed significant growth inhibitory effect on four treated plants, with dicot plants (lettuce and amaranth) being more sensitive than the tested monocot plants (wheat and ryegrass). Further investigation led to the isolation of harmaline and harmine as the main active ingredients in the total alkaloids of P. harmala seeds. Harmaline exerted potent inhibitory effects on seedling growth of treated plants, especially dicots, inhibiting root elongation of lettuce and amaranth by 31% and 47% at a very low concentration (5 µg/mL), whereas harmine exhibited much weaker non-selective inhibitory effect on the plants. Considering the high yield and poor utilization of P. harmala in China, we anticipate that this plant could be exploited as an alternative weed management tool in the future.