Neopterin production in SCID mice injected with human peripheral blood mononuclear cells

Neopterin, a prognostic marker in human malignancies

Increased neopterin concentrations are established in patients with an activated cellular (= Th1-type) immune response which includes allograft rejection, viral infection and autoimmune disorders as well as various malignant tumors. In patients with several types of cancer, neopterin concentrations in body fluids like urine, serum/plasma or ascites parallel the course of the disease, and a higher neopterin concentration in patients is an independent predictor of a shorter survival period. Neopterin is released in large amounts from human monocyte-derived macrophages and dendritic cells preferentially following stimulation with the pro-inflammatory cytokine interferon-gamma, thus reflecting the immune activation status. Therefore, not only as a laboratory diagnostic tool, the measurement of neopterin concentrations allows studying the immunological network and its interaction with the pathogenesis of tumor development. It contributes to a better understanding how immune activation is involved in the development of tumor-induced immune escape and tumor antigen specific tolerance.

Allergenic sensitization prevents upregulation of haemopoiesis by cyclo-oxygenase inhibitors in mice

1. We evaluated whether immunization affects bone-marrow responses to indomethacin, because allergenic sensitization and challenge upregulate responses to haemopoietic cytokines (including IL-5-driven eosinopoiesis) in murine bone-marrow, while indomethacin upregulates haemopoiesis and protects bone-marrow from radiation damage. 2. Progenitor (semi-solid) and/or precursor (liquid) cultures were established from bone-marrow of: (a) normal mice; (b) ovalbumin-sensitized mice, with or without intranasal challenge. Cultures were established with GM-CSF (2 ng ml(-1)) or IL-5 (1 ng ml(-1)), respectively, alone or associated with indomethacin (10(-7) - 10(-11) M) or aspirin (10(-7) - 10(-8) M). Total myeloid colony numbers and numbers of eosinophil-peroxidase-positive cells were determined at day 7. 3. In naïve BALB/c mice, indomethacin (10(-7) - 10(-9) M) increased GM-CSF-stimulated myeloid colony formation (P=0.003 and P=0.009, respectively). In contrast, it had no effect on bone-marrow of ovalbumin-sensitized and challenged mice. Indomethacin (10(-7) - 10(-9) M) also increased eosinophil precursor responses to IL-5 in bone-marrow of naïve (P<0.001 and P=0.002 respectively), but not sensitized-challenged mice. Aspirin (10(-7) M) had similar effects, equally abolished by sensitization. Enhancement of haemopoiesis by indomethacin required adherent cells from naïve bone-marrow. Nonadherent cells responded to IL-5 but not to indomethacin. Indomethacin was effective on bone-marrow from sham-sensitized, ovalbumin-challenged, but not from sensitized, saline-challenged mice. Plasma transfer from immune mice abolished eosinophil precursor responses to indomethacin in bone-marrow of naïve recipients. This was not prevented by previous removal of antibody from immune plasma. 4. COX inhibitors enhance haemopoiesis in naïve but not allergic mice. Responsiveness to indomethacin can be abolished either by active sensitization or by immune plasma transfer. Specific antibody is not involved.