Macroscopic and microscopic evaluation of Eurasian lynx (Lynx lynx) female tubular reproductive organs in relation to ovarian structures

Although monitoring wild animals in the field is essential for estimations of population size and development, there are pitfalls associated with field monitoring. In addition, some detailed data about reproductive physiology can be difficult to obtain in wild live animals. Studying reproductive organs from the Eurasian lynx killed at hunting or found dead could be used as a valuable addition to other field data. We evaluated reproductive organs from 39 Eurasian lynx females (Lynx lynx) killed in Sweden during the hunting seasons in 2009, 2010, and 2011. According to notes on ovarian structures, the animals were categorized as being in one of four different reproductive stages: juvenile (n = 10), follicular stage (n = 8), luteal stage (n = 11), and anestrus (n = 10). Corpora lutea were classified as fresh CL from the present season or as luteal bodies from previous cycles. Microscopic evaluations were blindly coded while the outer measurements of the vagina and uterus were taken at the time of organ retrieval. The width of the endometrium, myometrium, outer width of the uterine horns, and the diameter of the vagina differed significantly with the reproductive stage (P < 0.001) and were largest in the follicular and luteal phases. The number of endometrial glands evaluated blindly coded on a subjective scale was significantly associated with the reproductive stage (P < 0.0001) and was significantly higher in the luteal phase than that in any other reproductive stages (P < 0.05). Cornification of the vaginal epithelium was only observed in females in the follicular stage or in females with signs of a recent ovulation. In conclusion, both macroscopic and histologic measurements are useful for a correct classification of the reproductive stage when evaluating reproductive organs in the Eurasian lynx killed during the hunting season. Routine evaluation of reproductive organs has a potential to be a useful additional tool to field studies of live lynx to monitor their reproduction.

A protein disulfide isomerase/thioredoxin-1 complex is physically attached to exofacial membrane tumor necrosis factor receptors: overexpression in chronic lymphocytic leukemia cells

AIMS

The 3D structures and functions of cysteine-rich receptors such as tumor necrosis factor receptors (TNFRs) are redox-modulated by dithiol-disulfide exchange. TNFR superfamily members participate in growth regulation in B-cell chronic lymphocytic leukemia (CLL), and tissue stromal cells interact with leukemia cells, profoundly affecting their viability via release of redox-active components, including cysteine, thioredoxin-1 (Trx1), and Trx reductase. Trx1 was previously shown to enhance release of TNF, which acts as an autocrine/paracrine growth factor in CLL. The nature of the mechanism is not known, however. Here, we investigated whether Trx1 and protein disulfide isomerase (PDI), a chaperone and Trx-family member, may interact with TNFRs.

RESULTS

We found direct physical association between PDI and TNFR1 or TNFR2 by coclustering and affinity isolation. PDI (57 kDa) formed covalent/reduction-sensitive 69-kDa complexes with Trx1 (12 kDa) in a majority of CLL cell samples, detected at low levels only in control B-cells. Functionally, the TNF/TNFR signaling via the nuclear factor kappa B-driven autocrine loop was disrupted in a dose-dependent fashion by PDI-inhibitors bacitracin, anti-PDI, or anti-Trx1 antibodies, resulting in reduced viability. PDI was significantly overexpressed in immunoglobulin heavy-chain variable (IGHV) unmutated versus mutated CLL (p=0.0102), and amplified TNF release was observed in the former group.

INNOVATION

This study points out a previously unrecognized physical and functional association of TNFRs with the redox-active proteins PDI and Trx1.

CONCLUSION

We describe here a new level of TNF regulation, in which membrane TNFRs are redox controlled at the exofacial surface by PDI/Trx1. These findings shed new light on the observed survival benefit in CLL B-cells exerted by TNFR-superfamily ligands and point at potential therapeutic strategies.

Myelin protein zero is naturally processed in the B cells of monoclonal gammopathy of undetermined significance of immunoglobulin M isotype: aberrant triggering of a patient's T cells

BACKGROUND

Monoclonal gammopathy of undetermined significance of immunoglobulin M isotype is a condition with clonally expanded B cells, recently suggested to have an infectious origin. This monoclonal gammopathy is frequently associated with polyneuropathy and antibodies against myelin protein zero, whereas the role of the T cells remains largely unknown. We analyzed protein zero-specific B cells, as antigen-presenting cells, and their capacity to activate T helper cells.

DESIGN AND METHODS

We used a well-characterized monoclonal gammopathy of undetermined significance-derived B-cell line, TJ2, expressing anti-protein zero immunoglobulin M. The ability of TJ2 cells to bind, endocytose, process, and present protein zero was investigated by receptor-clustering and immunofluorescence. The activation of protein zero-specific autologous T cells was studied by measuring interleukin-2 and interferon-gamma with flow cytometry, immunobeads, and enzyme-linked immunospot assays.

RESULTS

Surface-receptor clustering and endocytosis of receptor-ligand (immunoglobulin M/protein zero) complexes were pronounced after exposure to protein zero. Naturally processed or synthetic protein zero peptide (194-208)-pulsed TJ2 cells significantly induced interleukin-2 secretion from autologous T cells compared to control antigen-pulsed cells (P<0.001). The numbers of interferon-gamma-producing T helper cells, including CD4(+)/CD8(+) cells, were also significantly increased (P=0.0152). Affinity-isolated naturally processed myelin peptides were potent interferon-gamma stimulators for autologous peripheral blood mononuclear cells, but not for control peripheral blood mononuclear cells.

CONCLUSIONS

We show for the first time that myelin protein zero is naturally processed in B cells from monoclonal gammopathy of undetermined significance of immunoglobulin M isotype, acting as aberrant antigen-presenting cells in activation of a patient's T helper cells. Our findings cast new light on the important role of autoreactive protein zero-specific B cells in the induction of the pathogenic T-cell responses found in nerve lesions of patients with monoclonal gammopathy of undetermined significance with peripheral neuropathy.

Facing inadequacy and being good enough: psychiatric care providers' narratives about experiencing and coping with troubled conscience

The aim of this study is to illuminate the meaning of encounters with a troubled conscience among psychiatric therapists. Psychiatric care involves ethical dilemmas which may affect conscience. Conscience relates to keeping or losing a sense of personal integrity when making judgments about one's actions. Ten psychiatric therapists were interviewed in June 2006. The interviews were tape-recorded, transcribed verbatim and interpreted using a phenomenological-hermeneutic method. Two themes 'Facing inadequacy' and 'Struggling to view oneself as being 'good enough'' are presented. In the therapists interviewed, awareness of their use of power, a sense of powerlessness and a sense of blame gave rise to feelings of betrayals and shameful inadequacy. By sharing their inadequacy with co-workers, they managed to endure the sense of their inadequacy which otherwise would have threatened to paralyse them. Finding consolation in sharing wearing feelings, becoming realistic and attesting their worthiness, they reached reconciliation and found confirmation of being good enough. The findings are interpreted in light of Lögstrup's ethics of trust, according to which conscience alerts us to silent but radical ethical demand and the risk of self-deception.

Redox-signaling transmitted in trans to neighboring cells by melanoma-derived TNF-containing exosomes

Hydrogen peroxide is known to be involved in redox signaling pathways that regulate normal processes and disease progression, including cytokine signaling, oxidative stress, and cancer. In studies on immune surveillance against cancer, hydrogen peroxide was found to disrupt cytotoxic T-cell function, thus contributing to tumor escape. In this study, secretion of TNF-containing vesicles of rab9+ endosomal origin, termed exosomes, was investigated using GFP-TNF constructs. We observed a polarized intracellular trafficking and apical secretion of TNF-positive nanovesicles. Cell-to-cell transfer of TNF was observed in exosomes in real-time microscopy, occurring separate from the melanin/melanosome compartment. Exosomes were prepared by ultracentrifugation or immunoisolation on anti-beta2-microglobulin magnetic beads. TNF as well as TNF receptors 1 and 2 were present in the exosomes as determined by Western blot, flow cytometry, and deconvolution microscopy. The functional significance of melanoma-derived exosomes was established by their signaling competence with ability to generate significantly higher ROS levels in T cells compared with sham exosomes (P=0.0006). In conclusion, we report here, for the first time, that TNF is found in tumor cell-derived exosomes and that these exosomes transmit redox signaling in trans to neighboring cells. The results are of importance for a better understanding of tumor escape mechanisms.

Selenite-induced apoptosis in doxorubicin-resistant cells and effects on the thioredoxin system

Selenium treatment of the doxorubicin-resistant cell line, U-1285dox, derived from human small cell carcinoma of the lung, resulted in massive apoptosis. This effect appeared maximal at 2 days after addition of selenite. The apoptosis was caspase-3 independent as revealed by Western blot analysis, activity measurement and by using caspase inhibitors. Induction of apoptosis was significantly more pronounced and occurred after addition of lower concentrations of selenite in the doxorubicin-resistant cells compared to the parental doxorubicin-sensitive cells. High levels of selenite caused necrosis in the doxorubicin-sensitive cells. Analysis of enzymatic activity (insulin reduction) of thioredoxin reductase (TrxR) and TrxR protein concentration, measured by ELISA, revealed increasing activity and protein levels after treatment with increasing concentrations of selenium. Maximum relative increase was induced up to 1 microM in both sublines and at this selenium level the concentrations of TrxR measured as insulin reducing activity or ELISA immunoreactivity were nearly identical. Increasing concentrations of selenite up to 10 microM resulted in increased activity and concentration of TrxR in the sensitive subline but decreasing levels in the resistant subline. The level of truncated Trx (tTrx) was higher in the resistant U-1285dox cells but the level did not change with increasing selenite concentrations. Our results demonstrate pronounced selective selenium-mediated apoptosis in therapy-resistant cells and suggest that redox regulation through the thioredoxin system is an important target for cancer therapy.

Enzyme-linked immunospot assay for detection of thioredoxin and thioredoxin reductase secretion from cells

Oxidative stress response was determined in this study by enzyme-linked immunospot (ELISpot) assays for thioredoxin (Trx) and Trx reductase (TrxR). On exposure to oxidative stress, cells can launch a variety of defense mechanisms, including release of antioxidant proteins. The Trx system, consisting of Trx, TrxR, and NADPH, constitutes one of these cellular defense systems for maintenance of a healthy reduction-oxidation (redox) balance. Trx and TrxR are rapidly upregulated and released from monocytes, lymphocytes, and other normal and neoplastic cells on exposure. Secreted Trx and TrxR have proved to be eminent indicators of oxidative stress. Trx is a small, 12-kDa protein released through a leaderless pathway, whereas TrxR, which is a 116-kDa selenoprotein and required for regeneration of Trx, is secreted through the Golgi pathway. In this chapter we present a detailed laboratory bench protocol for enumeration of single cells secreting redox-active Trx and TrxR after oxidative stress exposure. Physiological stimuli (such as interferon gamma, lipopolysaccharide, interleukin 1, and CD23 ligation; and phorbol 12-myristate 13-acetate and ionophore) as well as UV light and hydrogen peroxide were used to generate oxidative stress, and some are presented in detail. The protocol includes a description of cell isolation, preparation, handling, and development of ELISpot plates, troubleshooting notes, presentation of results, statistical evaluation, and comments on alternative sources of materials and manufacturer Web addresses. We concluded that the ELISpot assay is a useful method for detection of single cells secreting the redox-active proteins Trx and TrxR after oxidative stress exposure.

Thioredoxin reductase, a redox-active selenoprotein, is secreted by normal and neoplastic cells: presence in human plasma

Thioredoxin (Trx) and Trx reductase (TrxR) are redox-active proteins that participate in multiple cellular events, including growth promotion, apoptosis, and cytoprotection. Studies on overexpression of Trx and TrxR in human cancers have indicated a role of these proteins in tumor development. In this study, we analyzed the expression of TrxR in peripheral blood cells, tumor-transformed leukemia, and melanoma cells and found, in addition to abundant plasma membrane localization, that TrxR was released from these cells. Secretory cells were observed at the single cell level using a sensitive enzyme-linked immunospot assay. The release was inducible, and physiological stimulation of human monocytes by IFN-gamma, lipopolysaccharide, and interleukin 1alpha significantly increased the number of TrxR-secreting cells (P = 0.004). Secretion of TrxR followed the classical Golgi pathway, and it was confirmed by metabolic labeling using [35S]methionine and [35S]cysteine. TrxR was also detected for the first time in fresh healthy blood donor plasma (n = 21; median concentration, 18.0 ng/ml), with biological activity as determined by insulin reduction assay. These results highlight the role of extracellular Trx and TrxR during inflammation and tumor progression. Released Trx, with its active site motif containing amino acids Cys-X-X-Cys, was recently shown to have chemoattractant properties beside its previously described antioxidant and cocytokine activities. Regeneration of oxidized Trx requires available TrxR outside the cell, the presence and induction of which is described in this paper for normal and transformed cells.

Transforming desolation into consolation: the meaning of being in situations of ethical difficulty in intensive care

The purpose of this phenomenological-hermeneutic study was to illuminate the meaning of being in ethically difficult care situations. The participants were 20 enrolled nurses employed in six intensive care units in Sweden. The results reveal a complex human process manifested in relation to one's inner self and the other person, which transforms desolation into consolation through becoming present to the suffering other when perceiving fragility rather than tragedy. The main point of significance here is for all health professionals to create an ethical work environment and strive for praxis that fosters 'at-homeness', which renders us free to transform desolation into consolation. Consolation is of significance in ethics because it makes us available and helps us to fulfil the demands of life, while desolation makes us unavailable to others.

Monoclonal antibodies to human thioredoxin reductase

The thioredoxin system consisting of thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH is an electron donor for ribonucleotide reductase but has also been implicated in other cellular events, including secretion, growth promotion, regulation of transcription factors, protection against oxidative stress, and apoptosis. Mammalian TrxR is a dimeric flavoprotein with 58 kDa subunits each with a catalytically active selenocysteine residue. To study the function and expression of TrxR, we have produced and characterized, for the first time, monoclonal antibodies against human TrxR. Native placenta TrxR was used for immunization of BALB/c mice, followed by hybridization, cloning, and establishment of hybridomas producing specific antibodies against human TrxR. Three clones of IgG1, kappa subclass, termed anti-TrxR1, anti-TrxR2, and anti-TrxR3, were studied in detail. The isoelectric points (pIs) of the mAbs were 6.5, 6.0, and 6.5, respectively. The affinities (Ka) of the mAbs were 2 x 10(8) M-1. Inhibition ELISA using biotin-labeled versus nonconjugated mAb IgG revealed that all three mAbs recognized one immunodominant epitope. Western blot analysis showed that the antibodies specifically bound to a 58 kDa protein, representing the subunit of TrxR. A Trx-dependent insulin reduction assay was used for analysis of enzymatic activity and the antibodies neutralized the reductase activity.

Thioredoxin expression and localization in human cell lines: detection of full-length and truncated species

Thioredoxin (Trx) is an intracellular multifunctional 12-kDa protein with a reduction/oxidation (redox) active disulfide constitutively expressed by most cells of the human body. Trx can also be released by cells such as lymphocytes upon activation or oxidative stress exposure and exert a cocytokine and cytoprotective activity. In addition, a truncated 10-kDa form of Trx has been reported. In order to better understand the function of full-length and truncated Trx, we have produced, for the first time, specific monoclonal antibodies, which can discriminate between the two forms. Using these novel antibodies, designated alpha Trx1 to alpha Trx4, a panel of cell lines derived from human B and T lymphocytes, monocytes, granulocytes, and melanomas was analyzed by immunochemical techniques. The cellular distribution differed between the two forms. All lines contained full-length Trx, also located to a minor extent on the cell surface. One exception was the melanoma cell line FM28.4, which did not show any Trx expression. Truncated Trx was present in most cells in minimal amounts only, whereas the monocytic cell lines THP-1 and U-937 expressed high amounts on the cell surface, as shown by flow cytometric analysis of living cells and confocal laser-scanning microscopy. The biological importance and function of the short versus long forms of Trx as detected by the antibodies are discussed.

Dignity in situations of ethical difficulty in intensive care

In intensive care, situations of ethical difficulty are common. For the purpose of illuminating the meaning of being in ethically difficult situations, 20 registered nurses (RNs) employed in six intensive care units in Sweden narrated episodes of ethical difficulty. From a phenomenological hermeneutic perspective, the core theme of 'dignity' was identified in 85 stories. Stories with the concept of dignity reveal a threefold meaning; transforming disrespect into respect for the inviolable value of the human being; transforming ugly situations into beautiful ones; transforming discord of death into togetherness. Stories without the concept of dignity were oriented toward skills and physical care without reflection on actions and a 'taken-for-granted attitude' that good will prevail. Comparing and contrasting stories with and without dignity revealed the demands of dignity: attentiveness, awareness, personal responsibility, engagement, fraternity and active defence of dignity. In light of the philosophies of Weil, Marcel and Ricoeur, the demands of dignity correspond to qualities generated when struggling for respecting the dignity of human beings. This study reveals that dignity begets dignity, which opens the RNs to the ethical dimension. This, in turn, counteracts the risk of dehumanizing care in technocratic environments.

Meeting tragedy: interviews about situations of ethical difficulty in intensive care

For the purpose of illuminating the meaning of being in ethically difficult situations, eight enrolled nurses, 12 registered nurses and 10 physicians (n = 30) working in intensive care units in Sweden were asked to narrate care episodes of ethical difficulty. A phenomenological-hermeneutical analysis of the 30 narratives about nine care episodes disclosed that all stories concerned meeting tragedy, which evoked a spirit of compassion that pointed to values. The 'intention of compassion' aimed at respecting these ethical values. Respecting ethical values meant being consoled, which generated confidence in life that helped the person to embrace tragedy. When values were not respected, ethical problems emerged. Communication of values facilitated realisation, while unconscious values were indirectly communicated through emotions. Such communication meant risking vulnerability and meeting oneself. Meeting self and one's vulnerability demanded abilities of being consoled, i.e. in this study giving consolation, providing realistic treatment and being faithful in one's profession. A prerequisite for expressing personal standpoints and cooperating in the struggles of respecting ethical values was holding each other in great respect. When meeting tragedy, the spirit of compassion pointed to ethical problems, to the possibilities of solving the problems, and to the fulfilment of vision through converting feelings of despair into action energy.

Intensive care: situations of ethical difficulty

Twenty enrolled nurses (ENs), 20 registered nurses (RNs) and 20 physicians working in intensive care in northern Sweden narrated 255 stories about their experience of being in ethically difficult care situations. The ENs' stories mainly concerned problems relating to relationship ethics, the stories narrated by the physicians mainly concerned problems relating to action ethics, while the RNs' stories gave equal attention to both kinds of problems. The most common theme of both the RNs' and the physicians' stories was that of too much treatment. An obvious similarity between the ENs, RNs and physicians was that they saw themselves as equally lacking in influence in ethically difficult care situations. The only apparent difference between the three groups, however, was that the ENs brought up relationship problems more often than the others. Thus, the differences between the RNs and the physicians were fewer than usually reported in the literature. This might be related to the specialization of intensive care.

Growth inhibitory activity in extracts from human fibroblasts

Indirect evidence for the presence of a growth inhibitor in normal human fibroblasts has been obtained previously; the inhibitory activity has been found associated with crude cell extracts, but the molecule responsible for the growth inhibition has never been isolated. We have isolated a glycopeptide fraction from human fibroblast cultures, whose synthesis decreases when the cells are stimulated into the division cycle. It was separated by electric charge, lectin affinity, and molecular mass. When added to quiescent cells simultaneously with a growth stimulus, the glycopeptide reduces DNA synthesis activity. The relationship of the kinetics of the synthesis of the glycopeptide with the cell division cycle and its molecular weight are different from what has been described so far for other growth regulators. The decreased synthesis of this inhibitor, induced by growth factors, seems to be one of the requirements for the initiation of the division cycle by human fibroblasts. This response to growth factors was stable during the lifespan of the fibroblast population and became less pronounced only in cells at the end of their replicative potential.

Functional maturation of murine B lymphocyte precursors--III. Soluble factors involved in the regulation of growth and differentiation

When 5-fluorouracil (5-FU) resistant bone marrow (BM) cells are depleted of B-cells and then cultured in insert chambers [separated from a layer of adherent BM (aBM) cells by a nucleopore membrane], no mature, lipopolysaccharide (LPS) reactive B-cells are formed. Factors acting on B-cell precursors are not produced unless nonadherent accessory cells have been cultured with aBM cells in the surrounding well. Moreover, soluble products are insufficient to induce differentiation of B-cell precursors unless the cells have been conditioned by direct contact with aBM cells. Such preconditioned precursors complete differentiation when cultured with IL-3 plus IL-1 in dishes coated with fibronectin. In cultures supplemented with IL-3, IL-1 and fibronectin, a pleomorphic layer of aBM cells is generated after a few days. This is not the case in cultures lacking IL-3. Therefore, an important function of IL-3 may be to recruit an adherent accessory cell type from the pool containing precursors of the B-cell as well as myeloid lineages. This view is further supported by experiments on the generation of colonies containing antibody secreting B-cells from day 15 fetal liver precursors which depends on soluble products secreted by aBM cells. When aBM cells established in the absence of IL-3 are present, more than one cell type (or cell product) is limiting. However, if aBM cell layers are generated in the presence of IL-3, only B-cell precursors seem to be limiting. Since macrophages play an important role in the aBM population, the effect of CSF-1 was investigated. Even though CSF-1 potentiates the effect of IL-3 and IL-1, it cannot replace these interleukins. Like IL-3, it may influence B-cell differentiation in an indirect manner by modifying the microenvironment. Another important function of macrophages seems to be related to the production of C3, which binds to CR2 after degradation. P14, a peptide of the CR2 binding C3d fragment, strongly inhibits maturation of B-cell progenitors. A larger CR2 binding peptide, P28, is inhibitory at low concn but stimulatory at higher concn. It is assumed that aggregated P28 may cross-link with CR2 and thereby transfer a differentiation signal to the cell.

Functional maturation of murine B lymphocyte precursors. I. Selection of adherent cell-dependent precursors from bone marrow and fetal liver

A cell culture assay is described which is suitable to explore interactions between cells of the bone marrow (BM) microenvironment on one side and B lymphocyte progenitors on the other. First, a heterogeneous adherent BM (aBM) cell population was established on Cytodex 1 microcarriers. Then, adherent cell and surface IgM+(sIgM+) cell-depleted BM precursors or adherent cell-depleted day 12 fetal liver cells were added. The generation of B cells in these cultures was monitored by staining with fluorochrome-labeled anti-mu-chain antibody and by lipopolysaccharide (LPS) induction of protein A plaque-forming cells at limiting dilution. In the absence of aBM cells, some B cells arose after 24 hr from BM precursors but not from day 12 fetal liver cells. With aBM cells, BM precursors gave rise to a distinct second wave of B cells starting after 5 days of culture. When fetal liver cells were cultured on aBM cells, B cells appeared after a delay of 4 to 5 days. By using Ig allotype-congenic mouse strains (C.AL 20, BALB/c) and an allotype-specific plaque assay, we established that mature B cells originate from the putative progenitors and not from the aBM cell population. In an attempt to eliminate the aBM cell-independent progenitor subset, mice were pretreated with 5-fluorouracil 5 days before BM cells were collected. The remaining cells still contained B cells, but the frequency of c mu+ sIgM- pre-B cells was less than 10(-5). Remaining B cells were removed by anti-mu panning. In cultures of this precursor cell population, LPS-responsive B cells appeared after a delay of about 1 wk, and their generation was totally aBM cell-dependent and was maintained for more than 2 wk.

Functional maturation of murine B lymphocyte precursors. II. Analysis of cells required from the bone marrow microenvironment

The development of mature B cells in cultures of early B cell precursors depends on the presence of a confluent adherent bone marrow (aBM) cell layer. Adherent and sIgM+ cell-depleted bone marrow (BM) from untreated or 5-fluorouracil-pretreated donors or day 12 fetal liver cells were used as precursor cell populations. When adherent cells from thymus or highly enriched BM-derived macrophages were co-cultured with precursor cells, mature B cells were not developed. Similarly, aBM cell layers generated in the presence of hydrocortisone and horse serum were unable to support aBM cell-dependent precursor differentiation, even though cortisone was removed before the addition of precursor cells. In contrast, this type of microenvironment promoted the differentiation of precursor of myeloid cell lineages. Repeated treatment of established aBM cell populations with a monoclonal anti-macrophage antibody (31.3, known to recognize a surface marker on a subset of BM macrophages) and complement abolished the capacity of otherwise functional aBM cells to sustain the development of B cell precursors. Macrophage-depleted aBM cells regained their function after supplementation with highly enriched BM-derived macrophages grown in vitro. Limiting dilution analysis of aBM cells in microcultures containing saturating numbers of early B cell progenitors also suggests the participation of more than one cell type in the BM cell population. In conclusion, differentiation of early B cell progenitors requires macrophages in addition to at least one additional cell type contained in the aBM cell population.

Functional maturation of murine B lymphocyte precursors. I. Selection of adherent cell-dependent precursors from bone marrow and fetal liver

A cell culture assay is described which is suitable to explore interactions between cells of the bone marrow (BM) microenvironment on one side and B lymphocyte progenitors on the other. First, a heterogeneous adherent BM (aBM) cell population was established on Cytodex 1 microcarriers. Then, adherent cell and surface IgM+(sIgM+) cell-depleted BM precursors or adherent cell-depleted day 12 fetal liver cells were added. The generation of B cells in these cultures was monitored by staining with fluorochrome-labeled anti-mu-chain antibody and by lipopolysaccharide (LPS) induction of protein A plaque-forming cells at limiting dilution. In the absence of aBM cells, some B cells arose after 24 hr from BM precursors but not from day 12 fetal liver cells. With aBM cells, BM precursors gave rise to a distinct second wave of B cells starting after 5 days of culture. When fetal liver cells were cultured on aBM cells, B cells appeared after a delay of 4 to 5 days. By using Ig allotype-congenic mouse strains (C.AL 20, BALB/c) and an allotype-specific plaque assay, we established that mature B cells originate from the putative progenitors and not from the aBM cell population. In an attempt to eliminate the aBM cell-independent progenitor subset, mice were pretreated with 5-fluorouracil 5 days before BM cells were collected. The remaining cells still contained B cells, but the frequency of c mu+ sIgM- pre-B cells was less than 10(-5). Remaining B cells were removed by anti-mu panning. In cultures of this precursor cell population, LPS-responsive B cells appeared after a delay of about 1 wk, and their generation was totally aBM cell-dependent and was maintained for more than 2 wk.

Functional maturation of murine B lymphocyte precursors. II. Analysis of cells required from the bone marrow microenvironment

The development of mature B cells in cultures of early B cell precursors depends on the presence of a confluent adherent bone marrow (aBM) cell layer. Adherent and sIgM+ cell-depleted bone marrow (BM) from untreated or 5-fluorouracil-pretreated donors or day 12 fetal liver cells were used as precursor cell populations. When adherent cells from thymus or highly enriched BM-derived macrophages were co-cultured with precursor cells, mature B cells were not developed. Similarly, aBM cell layers generated in the presence of hydrocortisone and horse serum were unable to support aBM cell-dependent precursor differentiation, even though cortisone was removed before the addition of precursor cells. In contrast, this type of microenvironment promoted the differentiation of precursor of myeloid cell lineages. Repeated treatment of established aBM cell populations with a monoclonal anti-macrophage antibody (31.3, known to recognize a surface marker on a subset of BM macrophages) and complement abolished the capacity of otherwise functional aBM cells to sustain the development of B cell precursors. Macrophage-depleted aBM cells regained their function after supplementation with highly enriched BM-derived macrophages grown in vitro. Limiting dilution analysis of aBM cells in microcultures containing saturating numbers of early B cell progenitors also suggests the participation of more than one cell type in the BM cell population. In conclusion, differentiation of early B cell progenitors requires macrophages in addition to at least one additional cell type contained in the aBM cell population.

Hormonal responses to change in posture in hypertensive man. Evaluation by measurements of prostaglandin E2, renin activity, angiotensin II, and norepinephrine in renal venous blood

The hormonal responses to the stimulus of changing from resting supine to sitting upright for 15 minutes were assessed in 20 patients with hypertension, divided into 2 groups. 8 patients had essential hypertension (EH) and 12 unilateral renal artery stenosis (URS). The prostaglandin E2 (PGE2) concentration, plasma renin activity (PRA), angiotensin II (A-II) concentration, and norepinephrine (NE) concentration were measured in renal vein blood using specific methods. The PGE2 concentration increased after sitting for 15 minutes in all patients (p less than 0.001), but the increment was significant only in those with URS. The PRA was lower both at rest and after sitting up in the EH group than in the URS group. After sitting up the A-II concentration increased more in patients with URS than in those with EH (p less than 0.05). NE levels rose significantly when all patients were included (p less than 0.01), mainly owing to changes in the EH group. Supine and sitting PRA and A-II were correlated (r=0.47 and r=0.52; both p less than 0.05), and also sitting PGE2 and A-II (r=0.46, p less than 0.05). The inverse relation between PGE2 and NE for the difference in hormone concentrations between supine and sitting (r=-0.44, p less than 0.05) may be explained by an inhibitory effect of PGE2 on renal NE release, earlier observed in experiments in vitro. Similar changes in PGE2 and the measured components of the renin-angiotensin system in response to change in posture may indicate these factors are interrelated.

Limiting dilution analysis of the suppressive effect mediated by alloantigen-primed cells

T cells primed in mixed lymphocyte culture exert both positive and negative allogeneic effects on B cells expressing the appropriate alloantigens. The positive and negative effects can be separated by limiting dilution analysis: positive effects, measured by production of anti-sheep erythrocyte antibody, are revealed when low numbers of primed T cells are added to cultures of B cells and sheep erythrocytes, while suppression of the response occurs at higher T-cell inputs. In the present report, these negative allogeneic effects have been analysed in detail. Suppression was qualitatively and quantitatively similar when helper T cell activity was provided from any of several sources. Helper T cells in the alloantigen-primed population gave rise to active T-cell replacing factors even under conditions in which all microcultures were suppressed and suppressor cells were present at a high multiplicity in every well. The degree of suppression was influenced by the multiplicity of B cells in culture; as the number of B cells increased, more suppressor cells were required to inactivate a microculture. Taken together, these data indicate that the targets of the suppressor cells are B cells and not helper T cells or T-cell replacing factors. Although suppressor cells can prevent the activation of B cells by the more frequent helper cells in the primed T-cell population, detailed analysis of the stoichiometry of the suppression demonstrated that a single suppressor cell is capable of inactivating only a limited number of B cells, suggesting that a 'ratio-dominance' model of suppression is operative in this system.