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S Fossum

Publications and source records attributed to S Fossum.

At least 55 records · Page 3Linked to original sources
PubMed1989

[HIV screening of pregnant women and women seeking abortion. A preventive measure against HIV?].

In our opinion, screening of women seeking abortion and pregnant women does not benefit the work of HIV-prevention. Of the 115,600 tested from September 1987 to December 1988 in Norway, four new and HIV-positive and 92 false positive women were diagnosed. From the time screening started in September 1987 to the end of February 1989, the program has cost NOK 6-7 million. The prevalence of HIV among pregnant and abortion-seeking women is too low, and the problems associated with false positive results are too great for the project to be recommended. Pregnant women and women seeking abortion, and their partners, should be given the possibility of taking the HIV-test in the same manner as other low prevalence groups, where information and counselling are integrated and confidentiality is secured.

Abortion Applicants↗
PubMed1989

[Norwegian nomenclature in immunology].

Immunology represents one of the medical disciplines that has witnessed the fastest growth in new knowledge in recent decades. In the international journals the new concepts are introduced using English terminology. Norwegian immunologists are almost exclusively exposed to English immunological literature, and are therefore prone to adopt English rules of syntax when translating this literature into Norwegian. Two years ago a nomenclature-committee was established, with the mandate to ensure improved translations and, where relevant, to point out rules of syntax. The article presents the results from the work of this committee.

Allergy and Immunology↗
PubMed1989

[Heterosexual transmission of HIV--a predominantly female problem?].

Heterosexual dissemination of HIV is increasing in Norway. Women are apparently more exposed than men. 70% of Norwegian HIV-cases attributed to domestic heterosexual transmission are women. The two groups of sexual partners that most frequently infect Norwegian women with HIV are drug abusers and men from countries with a high prevalence of the disease. Physicians ought to be aware of this increase in heterosexual HIV-contamination, especially among younger women, so that they can undertake the public-health measures needed to delimit the spread of the disease. In particular, they should include sexual anamnesis in their examination of all cases where HIV-infection is a possibility.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The proliferation and life-span of rat large granular lymphocytes: effects of cytokines.

Pulse labeling of large granular lymphocytes (LGL) with [3H]thymidine for 1 h in vitro showed that 1%-7% of LGL were in S phase in the blood, spleen and liver of unstimulated euthymic and athymic rats as scored with autoradiography. Repetitive injections of [3H]thymidine over 2-7 days revealed that about half of the blood and spleen LGL had formed by division of precursors during this week. Stimulation of rats with the interferon inducer poly(I).poly(C) increased the proportion of S phase LGL rapidly and simultaneously in the blood, spleen and liver, so that by 20 h after stimulation ca 30% of LGL were in the S phase in these organs. This LGL proliferation was accompanied by an increased number of LGL in all three compartments 48-96 h after poly(I).poly(C) injection. Blood LGL cultured in cell impermeable diffusion chambers in the peritoneal cavity of poly(I).poly(C)-stimulated rats exhibited enhanced natural killer (NK) activity but no proliferative response, indicating that mature LGL were not induced to undergo blastogenesis by poly(I).poly(C) in vivo. Pretreatment of NK cells with rat interferon (IFN-alpha/beta) and with human recombinant interleukin 2 (rIL 2) in vitro, showed that these two cytokines, when combined, had opposing effects on NK activity and proliferation: whereas rIL 2 inhibited the IFN-induced augmentation in NK activity, IFN inhibited the rIL 2-induced LGL proliferation.

Animals↗
PubMed1989

Properties of lymph-borne (veiled) dendritic cells in culture. II. Expression of the IL-2 receptor: role of GM-CSF.

Fresh lymph-borne (veiled) dendritic cells (L-DC) in the rat are almost totally negative for the interleukin-2 (IL-2) receptor detected by the monoclonal antibody (mAb) MRC OX39. After 16 hr culture more than 90% of L-DC are OX39 positive, and increased levels of expression can be seen within 5 hr culture. In cultures of L-DC and allogeneic lymphocytes. L-DC appear to express the IL-2 receptor more rapidly than lymphocytes. The intensity of labelling of L-DC is variable but maximal levels are similar to those seen on lymphoblasts. Culture in the presence of concanavalin A (Con A)-stimulated spleen cell supernatants or recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) results in a more rapid and intense expression of the IL-2 receptor by L-DC. L-DC cultured following rigorous T-cell depletion, or derived from athymic rats also express the IL-2 receptor after culture with GM-CSF. Cultured, but not fresh, L-DC bind iodinated recombinant IL-2 in a dose-dependent manner and binding is inhibited by excess unlabelled ligand. The amount of IL-2 bound varies but maximal amounts are similar to those bound by lymphoblasts. Following intravenous endotoxin injection, a large proportion of freshly collected L-DC express the IL-2 receptor and the number of L-DC released into the lymph is increased. An antibody to the IL-2 receptor which blocks an allogeneic MLR has no effect on a xenogeneic MLR using rat L-DC as stimulators and mouse lymphocytes as responders.

Animals↗
PubMed1988

Lymph-borne dendritic leucocytes do not recirculate, but enter the lymph node paracortex to become interdigitating cells.

Peripheral lymph contains constitutively major histocompatibility complex (MHC) class II-positive, dendritic leucocytes (DL) with a veiled (VC) or dendritic (DC) shape. On the basis of phenotypic similarities to the interdigitating cells (IDC) of T-dependent areas of lymphoid tissues, they are believed, but not yet proven, to be IDC precursors that develop into mature IDC within the draining lymph nodes. In order to determine the relationship between VC/DC and IDC, highly purified radiolabelled peripheral lymph DL (collected by thoracic duct cannulation of mesenteric lymphadenectomized congenitally athymic, nude rats) were reinjected into the veins or footpads of syngeneic recipients. Later, host blood and lymph were collected and the tissues were biopsied and processed for scintillation counting or for light microscopic autoradiography combined with electron microscopy of neighbouring sections. The intravenously injected VC/DC did not enter lymph nodes or Peyer's patches directly from blood and did not re-enter the lamina propria of the gut, but became localized largely in the liver and the spleen. From the liver some of the cells proceeded via afferent lymphatics to the liver and the spleen. From the liver some of the cells proceeded via afferent lymphatics to the coeliac lymph nodes. Similarly, some of the locally injected cells were carried with peripheral lymph to the draining popliteal lymph nodes, although most were retained in the footpads. In the spleen the VC/DC entered the periarteriolar lymphoid sheaths and in the coeliac and popliteal lymph nodes they became localized in the paracortex, where they acquired the morphology of mature IDC.

Animals↗
PubMed1987

Specific inhibition of natural killer (NK) activity against different alloantigens.

Allogeneic lymphocyte cytotoxicity (ALC), i.e., rapid rejection of i.v. injected allogeneic lymphocytes in unprimed hosts, is an example of NK activity. Apparently anomalous rejection patterns, such as acceptance of F1 hybrid cells by parental hosts and rejection of parental cells by F1 hybrid hosts in many strain combinations, would fit the hypothesis that the effector cells in ALC recognize the absence of certain self-molecules (passwords) rather than the presence of nonself determinants. However, cold target inhibition studies showed that ALC displays allospecificity: when a mixture of radiolabeled AO and DA cells were injected i.v. into euthymic or athymic PVG rats, adding a surplus of cold DA cells reduced killing only of labeled DA cells and vice versa. Furthermore, semiallogeneic cold target cells were ineffective in inhibiting elimination of fully allogeneic cells, which supports the argument against a modification of the hypothesis that self-determinants inhibit a postbinding stage of lysis. Finally, (DA x AO)F1 cells injected into (DA x PVG)F1 hosts were rapidly rejected, despite the fact that donor and host shared expressed DA determinants. In sum, our results show that a hypothesis based on inhibition of killing by self-determinants can only be sustained with extensive modifications, and favor the alternative mechanism that the effector cells positively recognize the presence of allospecific determinants on the target cell surface.

Animals↗
PubMed1987

The localization of antigen in lymph node follicles of congenitally athymic nude rats.

We have examined the postulated dependence on T cells of follicular retention of antigen by studying antigen retention in the draining lymph nodes of congenitally athymic, nude rats after local injections of horseradish peroxidase (HRP). The lymphoid tissues of these rats contained germinal centres and follicular dendritic cells (FDC) that were ultrastructurally identical to those seen in euthymic rats and expressed the differentiation antigen MRC OX2. Nude rat FDC captured and retained locally injected antigen on their surfaces, but as with euthymic rats, only in the presence of previously injected anti-HRP antibody. This demonstrates that the FDC mature both morphologically and functionally in the absence of a thymus or T cells. However, in contrast to euthymic rats, there was no detectable antigen retention in nude rats that had been actively immunized by repeated intraperitoneal injections with HRP for 3 months. The lower number of germinal centres observed in athymic animals compared with their euthymic littermates could thus be explained by deficient production of specific antibody of the isotype necessary for follicular localization of environmental antigens.

Animals↗
PubMed1987

Allogeneic lymphocyte cytotoxicity (ALC) in rats: establishment of an in vitro assay, and direct evidence that cells with natural killer (NK) activity are involved in ALC.

The evidence that NK cells can recognize and kill allogeneic lymphocytes has hitherto been based mainly on experiments in intact animals. Here we report results from an in vitro assay, showing allogeneic lymphocyte cytotoxicity in cell suspensions enriched for NK activity against tumour cells by Percoll gradient centrifugation of nylon-wool non-adherent cells. The addition of phytohaemagglutinin (PHA) to the NK-target cell cultures greatly enhanced the cytotoxic response against K562 and allogeneic, but not syngeneic, lymphocytes. The effector cells of ALC are present in the spleen of both euthymic and athymic nude rats, and to a lesser extent in the blood. ALC is augmented by interferon pretreatment of the effector cells, and by depleting the effector cell suspensions of all T cells and helper T cells with the monoclonal antibody MRC Ox19 and W3/25, respectively. Conversely, the activity was nearly abolished by depleting the cell suspensions of MRC Ox8+ cells reacting with rat cytotoxic T cells and NK cells. Furthermore, removal of residual B cells (Ox12+ cells) from the effector cells or attempts to block any putative antibody-dependent cellular cytotoxic mechanism in vitro with the monoclonal antibody Ox12 did not inhibit the NK activity against allogeneic lymphocytes nor against tumour cells. ALC in vitro did not discriminate between T and B or large and small lymphocyte targets. These characteristics of the ALC effector cells substantiate that they are present within the thymus-independent population of cells with NK activity, and are dependent on neither B cells nor immunoglobulin for their recognition and destruction of the target.

Animals↗
PubMed1986

The roles of interdigitating cells and natural killer cells in the rapid rejection of allogeneic lymphocytes.

The fate of radiolabeled allogeneic thoracic duct lymphocytes injected into congenitally athymic, nude rats was followed by autoradiography and electron microscopy. The allogeneic cells entered the host lymphoid organs at a normal rate, but once inside the lymphoid tissue they were rapidly phagocytozed by interdigitating cells (IDC) situated in the lymph node paracortex and the splenic periarteriolar lymphoid sheaths. Neither host nor donor T cells were required to initiate phagocytosis, as purified donor B cells were also avidly ingested by the athymic host IDC. Compared with fully allogeneic cells phagocytosis of semiallogeneic donor cells was much less efficient. When natural killer cell activity was blocked by preinjecting the recipients with antibodies against natural killer cells (anti-asialo GM1 or MRC OX-8) phagocytosis of the allogeneic cells was strongly reduced. As IDC did not bind these antibodies, the finding indicates that natural killer cells were needed to discriminate between own and foreign lymphocytes and to kill the allogeneic cells, which were then ingested by surrounding IDC. This was further supported by the observation that dendritic, constitutively Ia+ cells from peripheral lymph, phenotypically identical to IDC, did not lyse or phagocytoze allogeneic lymphocytes in vitro.

Animals↗
PubMed1986

The host component of the popliteal lymph node graft-versus-host reaction. Selective representation of lymphocyte subsets and the requirement for alloantigenic incompatibility between donor cells and activated host B cells.

We have examined the cellular changes taking place in rat popliteal lymph nodes undergoing a graft-versus-host (GvH) reaction. Examination of immunoperoxidase-stained lymph node sections, using a panel of mouse monoclonal antibodies directed against different rat lymphoid cell subsets, revealed a disorganization of the lymph node architecture with disappearance of the follicles, and an intermingling of T and B cells, so that no distinct T- and B-cell areas were visible any more. Since the GvH nodes showed a preferential accumulation of host B cells over host T cells (particularly over the W 3/25+ T helper cell subset), we also investigated the requirements for host B cell activation. The popliteal lymph node GvH reaction was induced in (PVG X DA)F1 rats by the injection of PVG cells into one foot and by DA cells into the other foot, and then immunoglobulin kappa allotype marked PVG B cells from athymic donors were injected intravenously. The allotype marked B cells proliferated vigorously in response to the DA T cells, but much less in response to the PVG T cells. These results indicate that the massive B-cell activation taking place in GvH reactions may require an alloantigen incompatibility between donor T cells and host B cells, and argue against non-specific mitogenic induction of the B cells.

Animals↗
PubMed1985

The organization of cell populations within lymph nodes: their origin, life history and functional relationships.

The normal lymph node comprises a superficial cortex, a deep cortex or paracortex and a medulla. In each of these regions there are three kinds of spaces: an intralymphatic space, an intravascular space and an extravascular space or interstitium. Both the vascular endothelium and the lymphatic endothelium are specialized in these different regions. The cell types in lymph nodes comprise lymphoid cells, accessory or non-lymphoid cells and stromal cells, and within these cell types a number of different sub-types can now be identified by means of enzyme- and immunocytochemistry. Based predominantly on experimental studies, the origin, migratory patterns, localization, inter-relationships and interactions between these various cells are reviewed.

Animals↗