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T Timonen

Publications and source records attributed to T Timonen.

At least 73 records · Page 4Linked to original sources
PubMed1979

Human natural killer cell activity is augmented by interferon via recruitment of 'pre-NK' cells.

Contact with various cell-line targets increases the natural killer (NK) activity of human lymphocytes. Supernatants of such 20 h co-cultures augment the NK activity of virgin lymphocyte populations, and the augmenting factor penetrates 0.2 micrometer Millipore filters. The supernatants also contain interferon, and partially purified human leucocyte interferon increases NK activity when added to 20 h assays with 51Cr-labelled K-562 target cells. Potent anti-interferon antiserum added to the co-cultures inhibits the target-cell-induced augmentation phenomenon. Both the target-cell contact and interferon-induced augmentation affect a population of human lymphocytes, from which the 'mature' NK cells have been removed by adsorption-elution using fetal fibroblasts as adsorbents. The activity of 'mature' NK cells is not enhanced, and we conclude that the augmentation is mediated by recruitment of 'pre-NK' cells.

Adsorption↗
PubMed1979

Human natural cell-mediated cytotoxicity against fetal fibroblasts. IV. Comparison of cytotoxic activity with antibody-dependent cell-mediated cytotoxicity.

The dependence of human natural killer (NK) cell activity on antibodies was investigated. Absorption of the culture medium with target cells, trypsinization of the effector cells followed by a brief recovery, and incubation of the effector cells in serum-free nutrient medium did not affect natural killer cell activity against fetal fibroblasts. No soluble mediator in the nutrient media of effector cell--fibroblast co-cultures could be demonstrated. It was therefore concluded that antibodies are not involved in the cytolytic activity of natural killer cells. However, competition data and the activity of isolated NK cells against antibody-coated target cells suggested overlapping between the effector cells mediating natural and antibody-dependent cell-mediated cytotoxicity.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1977

A simplified isotope release assay for cell-mediated cytotoxicity against anchorage dependent target cells.

An assay for cell-mediated cytotoxicity has been developed in which anchorage-dependent target cells are cultured on small plastic beads in suspension. Confluent target cells on the beads are handled by methods appropriate to suspension-grown cells and labelled with chromium-51, iodine-125 and [3H]proline. Fetal human lung fibroblasts and HeLa cells were used as targets in model experiments measuring human natural killer cell activity. In 20 h experiments, chromium-51 was the most suitable isotope. In 40 h experiments, [3H]proline release assay was superior to chromium-51 and iodine-125 assays. The bead cytotoxicity assay offers a rapid and simple isotope release technique for anchorage dependent cells because no trypsinization and re-seeding of target cells is needed.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1976

Blocking effect of rheumatoid factor on the in vitro cytotoxicity of lymphoid cells from carcinoma patients.

Human cryo-IgM rheumatoid factor (RF) preparations blocked the tumor-specific in vitro cytotoxicity of ovarian or bladder carcinoma patients' lymphoid cells in microcytotoxicity assays. The effect was mediated by pretreatment of the effector cells. Cryo-IgM RF free of detectable IgG blocked in a dilution-dependent manner, and immunosorbent purification of contaminating IgG from another preparation did not abrogate the blocking effect. Control IgM preparations lacking RF activity did not block the cytotoxicity, and normal human serum preincubation of the RF preparations rendered them inactive, indicating that the blocking effect was due to the anti-IgG activity of the RF.

Cryoglobulins↗
PubMed1976

Cell-mediated anti-embryo cytotoxicity in human pregnancy.

The microcytotoxicity assay has been used to study human maternal cell-mediated immunity against foetal lung cells derived from foetal autopsies and amnion cells from full-term deliveries. Cytotoxicity against semi-allogeneic foetal lung cells but not against adult skin fibroblasts was detected in fourteen cases. No cytotoxicity was detected in six mothers tested during the first 15 weeks of gestation whereas 58% of mothers in the 15-17 weeks of gestation (twelve cases) and 88% with more advanced pregnancies (eight cases) were specifically cytotoxic. Cross-reactions against allogeneic foetal lung cells were mainly produced by effector cells from patients with 16-17-week-old pregnancies. No cytotoxicity was detected against semi-allogeneic amnion cells by effector cells from mothers after full-term deliveries. Cytotoxicity was blocked by autologous post-abortum sera in two out of seven cases. The effect of autologous post-abortum sera on non-cytotoxic effector cells was nonspecifically arming in four out of ten cases.

Amniotic Fluid↗