Human T-cell-porcine endothelial cell interactions induce human Th1 cytokines and porcine activation markers.

BACKGROUND: Since the future of clinical transplantation will undoubtedly include xenotransplantation, there is a need to examine human anti-pig cellular reactions. The objective of this study is to use human anti-porcine mixed lymphocyte endothelial cell culture (MLEC) to investigate cell interactions, cross-species molecular compatibilities, and the induction of human cytokines and porcine activation markers. METHODS: Human peripheral blood mononuclear cells or enriched CD4+ T cells depleted of professional antigen-presenting cells were cultured with resting pig aortic endothelial cells in the absence of exogenous cytokines. T-cell proliferative responses were measured and PAEC were monitored for cell surface markers by flow cytometry. Culture supernatants were assayed for human TNF-alpha and IFN-gamma by ELISA. RESULTS: Human T cells proliferated strongly in response to PAEC (median stimulation index = 75), even in serum-free cultures. High levels of the human Th1 cytokines TNF-alpha (20-350 pg/ml) and IFN-gamma (200-3800 pg/ml) were detected only in cultures containing PAEC, with levels peaking on Day 4. CD4+ T-cell-enriched, APC-depleted responders maintained proliferative anti-PAEC responses and cytokine release. By Day 3, MHC Class II and VCAM expression was induced in 92-96% PAEC: mean fluorescence intensity (MFI) increased from 5 to 83 +/- 12 and 166 +/- 74, respectively, and MHC Class I was increased from MFI 31 to 965 +/- 269. CONCLUSIONS: These results indicate that MLEC is an excellent in vitro model in which to study human anti-porcine cellular responses. Human T cells are activated in response to direct antigen presentation by PAEC, which are also activated in this system. Specific cytokines, receptors, and adhesion molecules appear to cross the xenograft barrier and play a critical role in T-cell - PAEC interactions. Such interactions are likely to affect VEC activation and immune responses to porcine xenografts in vivo.

Differential cytotoxicity of trace metals in cisplatin-sensitive and -resistant human ovarian cancer cells.

Cellular resistance of cisplatin is related to various factors such as membrane transformations, changes in cellular transport systems, and an increased efflux of cisplatin by the tumor cells. Deficiencies of one or more trace metals can affect normal physiological functions, leading to altered enzymatic activities and a reduction in immune responses. This in vitro investigation was undertaken to study and determine the differential cytotoxicity of certain trace metals in human ovarian cancer cells that were sensitive and resistant to cisplatin. Standard cytotoxicity assays were performed using the neutral red assay. In general, the cisplatin-resistant cells exhibited an increased resistance to the externally supplied trace metals. For both cell lines the rank order of cytotoxicity from greatest to least with the non-essential metals was Cd2+ > Bi3+, and for the macrometals, Ca2+ > K+ > Mg2+. The transition metals and selenium exhibited a slight difference between the two cell lines with respect to the order of cytotoxicity. The cisplatin-sensitive cells had a rank order of V5+ > Se6+ > Cu2+ > Zn2+ > Fe3+, from greatest to least toxicity. The cisplatin-resistant cells had a rank order of Cu2+ > V5+ > Se6+ > Zn2+ > Fe3+. Since trace metals have various functions in maintaining normal health, these results provide key baseline cytotoxicity data and show that, in general, cytotoxic resistance to the trace metals tested followed a pattern similar to cellular cisplatin resistance.

The cytotoxic interaction of inorganic trace elements with EDTA and cisplatin in sensitive and resistant human ovarian cancer cells.

Cisplatin (CDDP)-sensitive and -resistant human ovarian cells were studied in vitro with the objective of enhancing CDDP cytotoxicity by the addition of a metal and the chelate ethylenediaminetetraacetic acid (EDTA), to the CDDP. Chelateable elements, such as bismuth, calcium, cadmium, copper, iron, magnesium, selenium, vanadium, and zinc, when added to CDDP and in the presence of EDTA increased the cytotoxicity of the CDDP as compared to CDDP treatment alone.