The effect of non-steroidal anti-inflammatory drugs on osteosarcoma cells.

OBJECTIVE: Osteosarcoma (OS), an aggressive malignancy, is the most common primary bone tumor in children. Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used to reduce pain and inflammation. NSAIDs have shown to be toxic to certain malignancies such as colorectal, breast, and pancreatic cancers, but are not well-studied in OS. The purpose of this study is to assess whether ketorolac induces apoptosis in OS cells, compare this to indomethacin, which has been shown to inhibit OS proliferation, and explore the underlying mechanism. MATERIALS AND METHODS: A rat OS cell line (UMR-108) was exposed to various concentrations of ketorolac and indomethacin. Cell viability, cytotoxicity, apoptosis induction, DNA fragmentation and the expression of apoptosis-related markers were examined by MTT assay, colony formation assay, flow cytometry, agarose gel electrophoresis, and Western blot respectively. RESULTS: The results indicated that ketorolac and indomethacin could induce apoptosis of rat OS cells in a dose- and time-dependent manner. Apoptosis was confirmed by cell morphology and annexin positivity. The molecular data showed that NSAIDs affected expression of Bcl-2, survivin, and Poly (ADP-ribose) polymerase-1 (PARP). CONCLUSIONS: These findings demonstrated that NSAIDs induced apoptosis in rat OS cells in vitro. Further research focusing on the potential cytotoxicity of NSAIDs in vivo is needed.

Molecularly cloned SHIV-1157ipd3N4: a highly replication- competent, mucosally transmissible R5 simian-human immunodeficiency virus encoding HIV clade C Env.

Human immunodeficiency virus type 1 (HIV-1) clade C causes >50% of all HIV infections worldwide, and an estimated 90% of all transmissions occur mucosally with R5 strains. A pathogenic R5 simian-human immunodeficiency virus (SHIV) encoding HIV clade C env is highly desirable to evaluate candidate AIDS vaccines in nonhuman primates. To this end, we generated SHIV-1157i, a molecular clone from a Zambian infant isolate that carries HIV clade C env. SHIV-1157i was adapted by serial passage in five monkeys, three of which developed peripheral CD4(+) T-cell depletion. After the first inoculated monkey developed AIDS at week 137 postinoculation, transfer of its infected blood to a naïve animal induced memory T-cell depletion and thrombocytopenia within 3 months in the recipient. In parallel, genomic DNA from the blood donor was amplified to generate the late proviral clone SHIV-1157ipd3. To increase the replicative capacity of SHIV-1157ipd3, an extra NF-kappaB binding site was engineered into its 3' long terminal repeat, giving rise to SHIV-1157ipd3N4. This virus was exclusively R5 tropic and replicated more potently in rhesus peripheral blood mononuclear cells than SHIV-1157ipd3 in the presence of tumor necrosis factor alpha. Rhesus macaques of Indian and Chinese origin were next inoculated intrarectally with SHIV-1157ipd3N4; this virus replicated vigorously in both sets of monkeys. We conclude that SHIV-1157ipd3N4 is a highly replication-competent, mucosally transmissible R5 SHIV that represents a valuable tool to test candidate AIDS vaccines targeting HIV-1 clade C Env.

Anergy in peripheral memory CD4(+) T cells induced by low avidity engagement of T cell receptor.

Induction of tolerance in self-reactive memory T cells is an important process in the prevention of autoimmune responses against peripheral self-antigens in autoimmune diseases. Although naive T cells can readily be tolerized, memory T cells are less susceptible to tolerance induction. Recently, we demonstrated that low avidity engagement of T cell receptor (TCR) by low densities of agonist peptides induced anergy in T cell clones. Since memory T cells are more responsive to lower antigenic stimulation, we hypothesized that a low avidity TCR engagement may induce tolerance in memory T cells. We have explored two antigenic systems in two transgenic mouse models, and have tracked specific T cells that are primed and show memory phenotype. We demonstrate that memory CD4(+) T cells can be rendered anergic by presentation of low densities of agonist peptide-major histocompatibility complex complexes in vivo. We rule out other commonly accepted mechanisms for induction of T cell tolerance in vivo, such as deletion, ignorance, or immunosuppression. Anergy is the most likely mechanism because addition of interleukin 2-reversed anergy in specific T cells. Moreover, cytotoxic T lymphocyte antigen (CTLA)-4 plays a critical role in the induction of anergy because we observed that there was increased surface expression of CTLA-4 on anergized T cells, and that injection of anti-CTLA-4 blocking antibody restored anergy in vivo.

In vitro effects of various metals on natural killer cell activity in cultured human lymphocytes.

Heavy metals have been shown to have a differential effects on various aspects of immune response. Recently natural killer cells have been widely investigated due to their purported role in immune surveillance. To ascertain the immunotoxic effects of lead, cadmium, nickel and chromium on natural killer (NK) cell activity in vitro, peripheral blood lymphocytes from normal donors were examined in the presence of different concentrations (10(-5)-10(-8) M) of four selected metal salts (cadmium sulphate, lead nitrate, chromium nitrate and nickel sulphate). NK cell activity was evaluated in a 4-h chromium release assay against K562 target cells. All of the metal salts were found to exert no effect on NK cell function in the human concentration range.

Induction of T cell anergy by low numbers of agonist ligands.

Engagement of TCR by its ligand, the MHC/peptide complex, causes T cell activation. T cells respond positively to stimulation with agonists, and are inhibited by antagonist MHC/peptide ligands. Failure to induce proper conformational changes in the TCR or fast TCR/MHC dissociation are the leading models proposed to explain anergy induction by antagonist ligands. In this study, we demonstrate that presentation of between 1 and 10 complexes of agonist/MHC II by unfixed APC induces T cell anergy that persists up to 7 days and has characteristics similar to anergy induced by antagonist ligand or TCR occupancy without costimulation. Furthermore, anergy-inducing doses of hemagglutinin 306-318 peptide led to the engagement of less than 1000 TCR/CD3 complexes. Thus, engagement of a subthreshold number of TCR by either a low density of agonist/MHC or a 2-3 orders of magnitude higher density of antagonist/MHC causes anergy. Moreover, we show that anergy induced by low agonist concentrations is inhibited in the presence of IL-2 or cyclosporin A, suggesting involvement of the calcineurin signaling pathway.

Effects of some antigenic fractions of Leishmania major on nitric oxide production and IL-12 secretion by murine peritoneal macrophages.

Nitric oxide (NO) and IL-12 are important mediators of the immune response to Leishmania major. In this study, the effects of L. major promastigotes, crude antigenic fraction (CAF) and its subfractions on NO production and IL-12 secretion by BALB/c mice peritoneal macrophages is investigated. The subfractions of CAF, namely, fractions 1, 2 and 3, that were in the molecular weight range of 97.4-66, 66-45 and below 45 kDa, respectively, were separated by SDS-PAGE. NO production was determined by using Griess reagent and IL-12 was measured by ELISA. It was found that NO production was stimulated by promastigotes but not by CAF or its subfractions. IL-12 secretion was stimulated by promastigotes, CAF and fraction 1 while fractions 2 and 3 did not have any effect.

Effects of high-level exposure to lead on NK cell activity and T-lymphocyte functions in workers.

1. NK and T cell functions were measured in peripheral blood lymphocytes of workers occupationally exposed to lead. 2. No differences were found in these functions even in those workers with higher levels of blood and urine lead and urinary delta-ALA than the currently accepted biological limit values as compared to controls. 3. We conclude that high chronic exposure to lead is not associated with an impairment or either T- or NK cell functions in man.

Effects of crude antigenic fractions of Leishmania major on natural killer cell cytotoxicity, interferon-gamma and interleukin-4 secretion from peripheric blood lymphocytes of unexposed individuals.

The crude antigenic fraction (CAF) isolated from Leishmania major was fractionated into three subfractions by sodium dodecyl sulphate-polyacrylamide gel (SDS-PAGE). The effects of CAF and its subfractions on NK cell cytotoxicity is investigated by chromium release assay. These subfractions designated as fractions 1, 2 and 3 correspond to 97.4-66 kD, 66-45 kD and 29 kD and below respectively. Although both CAF and its subfractions have inhibited the cytotoxicity of natural killer (NK) cells, the effects of fractions 2 and 3 were more pronounced. The effect of the fractions on the Interferon-gamma (IFN-gamma) and Interleukin-4 (IL-4) secretion by peripheric blood lymphocytes was also analyzed. It was found that CAF and fraction 1 induce IFN-gamma secretion while on the other hand IL-4 secretion was mostly suppressed by fraction 2. Therefore, further research is being executed which focuses on the effects of CAF, fractions 1 and 2 on macrophage effector functions.