Search PubMed⌕ Search

Biomedical subjects

O Lassila

Publications and source records attributed to O Lassila.

At least 91 records · Page 5Linked to original sources
PubMed1983

Development of natural killer cell function in the human fetus.

NK cell activity of four human premature infants between 28 and 33 wk of gestation and eleven human fetuses at 9 to 22 wk of gestation was tested against the K-562 cell line in a 4-hr 51Cr-release assay. Cord blood lymphocytes from premature infants expressed well-developed NK capacity, although the level of cytotoxicity was lower than that of full-term newborns or adults. Cells prepared from fetal liver displayed cytotoxicity against K-562 targets in four out of eleven fetuses, whereas cells from fetal bone marrow, spleen, and thymus expressed only marginal or negative anti-K-562 killing. NK cell activity in the fetal liver was observed as early as at 9 wk of gestation. The functional NK capacity of premature infants and fetuses was augmented in vitro by IFN-alpha treatment. Fetal cells without spontaneous NK activity did not develop cytotoxicity against K-562 target cells in the presence of IFN-alpha. The present results corroborate the concept of the intrauterine development of human NK cell activity.

Female↗
PubMed1982

Migration of erythropoietic and prebursal stem cells from the early chicken embryo to the yolk sac.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk sac-embryo chimeras constructed of histoincompatible partners. The results obtained indicate that the early chick yolk sac produces transiently erythroid stem cells whereas definitive erythrocytes are derived from the intraembryonic stem cells. Such a change from the yolk sac-derived cells into embryo-derived cells is not observed in the lymphocytes which are exclusively derived from the embryo-borne stem cells. Experiments with cell transfers from the chimeric yolk sacs demonstrate that erythropoietic and prebursal stem cells migrate from the early embryo to the yolk sac during the second to the seventh day of incubation. The results obtained also exclude the de novo generation of prebursal stem cells in the yolk sac.

Animals↗
PubMed1982

Natural killer cell activity in atopic dermatitis.

Natural killer (NK) cell activity against K562 cells was studied in 12 male adults with atopic dermatitis (AD). In a 4-h chromium release microcytotoxicity assay normal NK cell function and its augmentation by interferon (IFN-alpha) were observed in AD patients. Slightly higher NK cell activity was observed in patients with allergic respiratory symptoms. The role of NK cells in the pathogenesis of atopic dermatitis is discussed.

Adolescent↗
PubMed1982

Cell-mediated immunity in normal pregnancy and pre-eclampsia.

The in vitro responses of maternal lymphocytes to phytohaemagglutinin (PHA), concanavalin A (Con A) and purified protein derivative of tuberculin (PPD) were determined in uncomplicated and pre-eclamptic pregnancies and nongravid female controls. PHA, Con A and PPD responses were significantly lower in both pregnant groups compared to nongravid controls. No difference was observed in lymphocyte reactivity between women with pre-eclampsia or uncomplicated pregnancy. Both pregnant groups exhibited normal numbers of circulating T and B lymphocytes. The number of active E rosette-forming cells was significantly higher in peripheral blood of pre-eclamptic patients.

Adolescent↗
PubMed1982

Alpha-naphthyl acetate esterase activity in human foetal lymphocytes.

Human foetal mononuclear cells from thymus, spleen, liver, bone marrow and peripheral blood at 8-24 weeks of gestation were examined for cytochemical evidence of acid alpha-naphthyl acetate esterase (ANAE) activity. The focal brownish-red ANAE reaction product (T cell staining pattern) was observed in counterstained cytocentrifuged cell smears in the cytoplasm. ANAE-positive lymphoid cells were first observed in the thymus at 9 weeks of gestation. A gradual increase in frequency of ANAE-positive cells in foetal thymus was observed, from about 10% at 14-15 weeks to about 20% at 22-24 weeks of gestation. By 14 weeks of foetal age, spleen and liver contained a few ANAE-positive cells and after 15 weeks of gestation consistent occurrence of ANAE-positive cells was observed in foetal bone marrow and peripheral blood. These results demonstrate that ANAE-positive lymphocytes first appear in the foetal thymus and are subsequently found in the foetal liver, spleen, bone marrow and peripheral blood.

Bone Marrow↗
PubMed1982

Migration of prebursal stem cells from the early chicken embryo to the yolk sac.

Allogeneic yolk sac-embryo chimaeras were constructed by association of B15B15 yolk sac and B2B2 embryo on day 2 of incubation. Five days later yolk sac cells from the chimaeras were injected intravenously into 14-day-old irradiated embryos, using recipients of B2B2 and B15B15 genotypes. One week after hatching, cells in the bursa of Fabricius and peripheral blood erythrocytes were studied for Ia-like antigens and B alloantigens, respectively, to determine whether they were derived from the embryo or yolk sac part of the chimaera. The results obtained demonstrate that prebursal and erythropoietic stem cells migrate from the early embryo to the yolk sac during the 2nd to the 7th day of incubation. They also exclude the de novo generation of prebursal stem cells in the yolk sac.

Aging↗
PubMed1982

Alpha-naphthyl acetate esterase activity in human adult and cord blood rosette forming cells.

Alpha-naphthyl acetate esterase (ANAE) activity was studied in cells forming rosettes with sheep and mouse erythrocytes. In adult peripheral blood, on the average 74% of E-rosette-forming cells expressed simultaneous focal ANAE activity, whereas most cells forming rosettes with mouse erythrocytes were negative. No difference was observed in ANAE-staining proportions of active and total E-rosette forming cells in adult peripheral blood. The proportions of total and active E-rosette and M-rosette forming cells were similar in adult peripheral blood and cord blood lymphocytes. However, the mean percentage of cord blood total E-rosette-forming cells expressing ANAE activity (61%) was significantly lower (P less than 0.001) than in adult peripheral blood.

Animals↗
PubMed1982

Natural killer cell function in trisomy-21 (Down's syndrome).

Natural killer (NK) activity and antibody-dependent cell mediated cytotoxicity (ADCC) against a human myeloid target cell line (K 562) was measured in adult patients with trisomy-21 (Down's syndrome) and in chromosomally normal age and sex matched control subjects. The effect of human leucocyte interferon (IFN-alpha) on the NK activity was also estimated. Spontaneous NK activity was stronger in the adult patients with trisomy-21 than in the healthy controls, but the difference did not reach statistical significance. The augmentation of NK activity by IFN-alpha, measured using lymphocytes not depleted of monocytes as effector cells, was statistically significant in both the trisomic patients (P less than 0.004) and the healthy controls (P less than 0.0005). Using monocyte and macrophage depleted lymphocytes in the patients with trisomy-21 the NK activity proved stronger than in the healthy controls, but not significantly and IFN-alpha did not augment it as it did in the healthy controls (P = n.s., P less than 0.05), for augmentations respectively). These results support the view that monocytes and macrophages are connected with the NK cell system. ADCC correlated with NK activity in both groups. Since NK cells are important components of many immune processes, including tumour and virus and/or bacteria-infected cell elimination, and have regulatory functions in immune reactions, the deficient augmentation of trisomic NK cells shown in vitro with extrinsic human leucocyte interferon may, paradoxically be an explanation for the greater susceptibility of trisomic individuals to lymphatic leukaemia and virus and bacterial infections. In vivo, this could be explained by the more potent secondary suppression by the 'immune' interferon produced by the virus, bacteria and malignant cells. In other words, the potential of the 'fighting couple' of the immune system, NK cell/interferon, is perhaps disturbed genetically due to the chromosome 21.

Adult↗
PubMed1982

Natural killer cell function of human neonatal lymphocytes.

Human natural killer cell (NK cell) activity against K-562 target cell line was evaluated in full term cord blood (n = 30) and adult peripheral blood (n = 20) using 51Cr release assay. The level of NK cell activity was lower in cord blood compared to adult controls (39.6 +/- 11.4% vs 27.4 +/- 11.8% at effector:target ratio 50:1). Adult males showed a significantly higher NK activity compared to females. No sex difference was observed in cord blood. Furthermore, partially purified human leucocyte interferon (IFN alpha) increased in vitro NK cell function of both adult and newborn lymphocytes. The present results indicate that the appearance and maturation of human NK cells occurs during the intrauterine life of the human fetus.

Adult↗
PubMed1982

Deficient natural killer cell function in preeclampsia.

Natural killer cell activity of peripheral blood lymphocytes was measured against K-562 target cells with a 4-hour 51Cr release assay in 15 primigravid women with preeclamptic symptoms. Nineteen primigravid women with an uncomplicated pregnancy and 18 nonpregnant women served as controls. The natural killer cell activity of preeclamptic women was observed to be significantly lower than that of both control groups. Natural killer cells in preeclamptic women responded normally to augmentation caused by interferon. These findings give further evidence for the participation of the maternal immune system in this pregnancy disorder.

Adult↗
PubMed1982

Induction of B cell differentiation in vitro by bursal epithelium.

The inductive capacity of in vitro cultured epithelium of chicken bursa of Fabricius and of its soluble products on B cells precursors was evaluated. The appearance of surface Ia-like antigens was used as an indicator of the early B cell differentiation in vitro. Cultured bursal epithelium as well as soluble substances produced by it were able to initiate B cell development; Ia alloantigens were induced by both syngeneic and allogeneic epithelia. In both cases the induced Ia antigens represented the genotype of the responding cells.

Animals↗
PubMed1982

Erythropoiesis and lymphopoiesis in the chick yolk-sac-embryo chimeras: contribution of yolk sac and intraembryonic stem cells.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk-sac-embryo chimeras differing at the B locus antigens. Erythroid cells derived from the yolk sac or from the intraembryonic mesenchyme were demonstrated by indirect immunofluorescence in the peripheral blood of these allogenic chimeras. At 7 days of incubation, yolk-sac-derived red cells represent a majority in the peripheral blood. From 9 days of incubation onwards, embryo-derived erythrocytes appear in increasing proportions, making up approximately 90% of the peripheral blood cells at 17-18 days of development. After hatching, no yolk-sac-derived erythrocytes are found in the peripheral blood. Such a change from the yolk-sac-derived cells into embryo-derived cells was not observed in the lymphocytes, as analyzed using specific anti-B and anti-la antisera for detection of thymus and bursa cells, respectively. Ia-like antigens were detected on bursa cells using a triple layer immunofluorescence system. These results obtained from the allogeneic chimeras indicate that the early chicken yolk sac produces only transiently erythroid stem cells, while intraembryonic stem cells are involved in the production of definitive erythrocytes as well as of lymphocytes, both of T and B cells.

Animals↗
PubMed1981

A rosette assay for identification of Ia-like alloantigens on chicken lymphoid cells.

An Ia-rosette assay for the detection of Ia-like alloantigens on the chicken lymphoid cell surface is described. The method is based on the ability of cells treated with alloantiserum to Ia and then with rabbit antiserum against the Fc portion of chicken IgG, to form rosettes with sheep erythrocytes (SRBC) coated with chicken anti-SRBC IgG antibody. Interference with Ia-rosette formation by Fc IgG receptors was eliminated by pronase treatment which removes Fc receptor activity without affecting Ia antigens. The Ia-rosette assay is at least as sensitive as the triple-layer immunofluorescence test for identification of Ia antigens. In addition, the assay allows morphological study and separation of the rosetting cells.

Animals↗
PubMed1981

Acid alpha-naphthyl acetate esterase activity in nucleated red cells of human fetal liver.

Acid alpha-naphthyl acetate esterase (ANAE) activity was investigated in nucleated red cells obtained from nine human fetal livers at 9-24 weeks of gestation. A strong ANAE activity was demonstrated in fetal liver erythroblasts with a staining pattern of a perinuclear ring. Occasionally some polychromatophilic normoblasts expressed a focal ANAE activity usually observed in human T-lymphocytes. Some 50-70% of erythroblasts in human fetal livers showed a ring-like staining pattern. A slight decrease of ANAE positivity was observed in cells of fetal livers after 17 weeks of gestation.

Carboxylic Ester Hydrolases↗