Search PubMed⌕ Search

Biomedical subjects

J Ennen

Publications and source records attributed to J Ennen.

23 records · Page 2Linked to original sources
PubMed1987

Large granular lymphocytes are central cells in the interleukin-2-dependent differentiation pathway of natural killer cells.

Peripheral blood low-density cells were sorted, with respect to their ability to accumulate the lysosomotropic agent mepacrine (Mep), into lysosome-rich (Mep+) and lysosome-poor (Mep-) cell populations. Cells of large granular lymphocyte (LGL) morphology and phenotype were found in the Mep+ but not in the Mep- cell population. The latter cells lacked any natural killer (NK) activity. Cultures of the Mep- cells resulted in the appearance of cells showing K-562 lytic activity, LGL morphology and CD16 and/or Leu-7 positivity. This process was facilitated by the supplementation of the culture with recombinant human interleukin-2 (rIL-2). Mep+ cells retested after 7 days of culture showed a decline in the fraction of granular (LGL and Mep+) cells. This decrease was less pronounced but also seen in rIL-2-supplemented cultures. In spite of the lower number of typical LGL, Mep+ cells cultured with rIL-2 were mostly large but scarcely granular; rIL-2-activated K-562 killing (rIL-2 AK) of originally Mep+ cells was much higher than K-562 lytic activity of these cells at the beginning of the culture, and as compared to rIL-2 AK of Mep- cells. From this finding it is apparent that the most active rIL-2 AK cells originate from low-density granular (Mep+) cells (LGL) and, therefore, we propose to call them 'giant' NK cells. Furthermore, in the presence of rIL-2, LGL differentiate from agranular (Mep-) low-density cells. In view of these data, LGL appear to be resting cells on the differentiation pathway of NK cells.

Cell Differentiation↗
PubMed1984

Dissociation of responses measured by natural cytotoxicity and chemiluminescence.

Monocyte/macrophage-mediated cytotoxicity requires the generation of activated oxygen radicals, which can be measured by chemiluminescence (CL). To investigate whether natural killer (NK) cell activity required activated oxygen species, both cytotoxicity against K562 target cells and CL were measured in cell populations of human peripheral blood. The following results were obtained: (a) Peripheral blood mononuclear cells (MNC) showed NK activity and a response in CL, which could be induced by viable or paraformaldehyde-fixed K562 target cells as well as by latex particles. (b) Both T cells and non-T cells exhibited NK activity, but T cells gave no K562- or latex-induced CL responses. (c) Depletion of phagocytic cells from MNC abolished CL, but only marginally affected NK activity. (d) Reconstitution of phagocyte-depleted MNC with adherent cells revealed a superadditive enhanced CL response, but had no augmenting effect on NK activity. (e) Phagocyte-depleted cell populations, enriched for NK activity by density gradient centrifugation, did not respond in K562- and latex-induced CL. (f) MNC, highly enriched for NK activity by cell sorting with a cytofluorograf using the fluorescein isothiocyanate-labeled monoclonal antibody anti-Leu-11a, responded only with reduced CL, whereas the NK activity was enriched up to 45-fold. From these results it is concluded that NK cell-mediated cytolysis of K562 target cells and K562-induced CL are not functionally correlated, but represent properties of two distinct cell populations, namely NK cells and monocytes.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1984

[The C3 activating capacity in human serum--measured as monocyte mediated chemiluminescence].

Phagocytosing monocytes form activated oxygen species which can be detected by the luminol-mediated chemiluminescence (CL). C3b-coated particles yield enhanced CL-signals due to their binding to the monocytes' C3b-receptor. Thus, the zymosan-induced monocyte-CL in a medium containing fresh or heat-inactivated serum provides a means of measuring in sera the capacity to activate C3.

Biological Assay↗
PubMedDate not supplied

Activation of human monocytes by interleukin 2: role of T lymphocytes.

The effect of interleukin 2 (IL2) on the capability of human monocytes to secrete reactive oxygen species triggered via Fc-gamma receptor (Fc-gamma R) function had been investigated by measurement of chemiluminescence (CL). IL 2 did not activate highly purified (hp) monocytes to respond to Fc-gamma R mediated phagocytic stimulation with an enhanced respiratory burst activity unless low numbers of T cells had been co-cultured with hp monocytes. Supernatants from IL 2 treated PBMC contained interferon-gamma (IFN-gamma) and monocyte activating factor (MAF) activity. The secretion of both cytokine activities was strongly enhanced by cooperative function of monocytes. The correlation of IL 2 induced secretion of IFN-gamma and MAF activity was striking, however, monoclonal antibody (mAb) anti-human IFN-gamma failed to abrogate IL 2 stimulated and lymphocyte dependent monocyte activation. Although IL 2 had no direct monocyte activating effect, pretreatment of hp monocytes with IL 2 led to monocyte priming: subsequent co-culture with autologous control T cells enhanced the monocyte Fc-gamma R mediated CL response. The priming of monocytes by IL 2 was dependent on the interaction of IL 2 with the monocytic IL 2 receptor as shown by inhibition experiments with anti IL 2 R monoclonal antibody. Thus the IL 2 driven monocyte/T-cell interaction leads to an increased Fc-gamma R mediated monocytic respiratory burst activity and to the secretion of a soluble MAF activity, but there were no detectable amounts of IFN-gamma.

Antibodies, Monoclonal↗