Biomedical subjects

D M Murasko

Publications and source records attributed to D M Murasko.

At least 37 records · Page 2Linked to original sources

PubMed1994

Differences between young and aged mice in susceptibility to Friend virus.

Friend virus (FV) is a murine leukemia virus that infects progenitor red blood cells and causes an erythroleukemia in susceptible mouse strains, resulting in splenomegaly. Several genetic loci of the host have been identified that affect erythroleukemia development, differentiation status of target cells and virus replication. Since age may change expression of these loci, age may affect FV disease. To explore this possibility, FV expression in four genetically diverse strains of mice of different ages was examined. Extent of viral replication and of disease were evaluated by measuring spleen focus forming units (SFFU), spleen weight and reverse transcriptase (RT) activity in target organs. Young DBA/2 and (C57BL/6 x DBA/2)F1 mice exhibited a greater level of virus expression than their aged counterparts in all parameters investigated. Young CBA/Ca mice had slightly higher spleen weights and SFFU values than aged CBA/Ca mice, but a definitive age-related change was not observed in the RT activity of the target organs. C57BL/6 mice, which are genetically resistant to the development of FV-induced erythroleukemia, exhibited a limited degree of virus replication that was not effected by the age of the animal. Our results indicate that the age of the mouse, as well as the genetic background, can contribute to the level of susceptibility to FV.

Aging↗

PubMed1994

Inhibition of macrophage-induced, antigen-specific T-cell proliferation by poly I:C role of suppressor macrophages.

Poly I:C treatment can inhibit the ability of macrophages (M phi) to induce antigen-specific T-cell proliferation. This study investigated whether this inhibition is the result of suppressor or cytotoxic activity. Pretreatment of M phi with indomethacin in vivo, in vitro or both failed to reverse the inhibition of T-cell proliferation induced by poly I:C-treated, keyhole limpet haemocyanin (KLH)-pulsed M phi, suggesting that prostaglandin production does not mediate the inhibition of T-cell proliferation. The transfer of supernatants from cultures containing poly I:C-treated, KLH-pulsed M phi to cultures containing saline-treated, KLH-pulsed M phi and T cells did not inhibit T-cell proliferation, suggesting that the inhibition of T-cell proliferation by poly I:C is not mediated by the production of soluble suppressor factors. As addition of poly I:C-treated, KLH-pulsed M phi to cultures containing saline-treated, KLH-pulsed M phi did not significantly inhibit KLH-specific T-cell proliferation, the inhibition of T-cell proliferation is also not mediated by direct cell contact or short-range soluble suppressor factors. In addition, poly I:C-treated, KLH-pulsed M phi did not induce cytolysis of syngeneic T cells. These results indicate that cytotoxic or suppressor effector functions of M phi are not involved in the mechanism by which poly I:C inhibits M phi-induced, antigen-specific T-cell proliferation.

Animals↗

PubMed1993

Anesthesia inhibits interferon-induced natural killer cell cytotoxicity via induction of CD8+ suppressor cells.

Anesthesia (Avertin, halothane, isoflurane, ether, or ketamine/xylazan) of mice inhibits subsequent stimulation of splenic natural killer cell (NK) cytotoxicity by interferon (IFN) treatment either in vitro and in vivo. The current data demonstrate (a) in vitro depletion of CD8+ cells from mononuclear splenocytes of anesthetized mice restored the ability of NK cells to respond in vitro to IFN stimulation and (b) coincubation of CD8+ splenocytes from anesthetized mice with CD8- splenocytes of naive mice resulted in a significant reduction of the IFN-induced stimulation of NK activity in the coculture. These results suggest that anesthesia induces CD8+ cells that suppress stimulation of NK cytotoxicity by IFN.

Anesthetics↗

PubMed1993

Age associated changes in mitogen induced proliferation and cytokine production by lymphocytes of the long-lived brown Norway rat.

The long-lived, inbred Brown Norway (BN) rat demonstrates an age associated decrease in lymphoproliferation in response to ConA; however, these declines only become apparent after the age of median survival, 31 months. Significant declines in IL-2 production after ConA stimulation also occur after median survival. In contrast, production of IFN after ConA stimulation increases with age in BN rats. This increase in IFN production begins about 12 months of age and plateaus at about median lifespan. The imbalance in IL-2 and IFN production may reflect a dysregulation that results in a decreased proliferative response of lymphocytes with increasing age.

Aging↗

PubMed1993

Maintenance of normal T lymphocyte function after transfection with SV40 large T.

Human T lymphocytes in culture undergo cellular senescence similar to that observed in fibroblasts. We recently demonstrated that senescence of T lymphocytes can be postponed by transfection with SV40 large T. In the current study, we examine the functional activity of SV40 large T transfected T lymphocytes. Transfected T cells of both young and elderly subjects appear to display normal T cell function: they cease doubling upon removal of IL-2; in the presence of autologous adherent mononuclear cells they respond to mitogen stimulation and produce IL-2 and IFN-gamma during proliferation; and they express both IL-2 and transferrin receptors similar to those observed in mitogen-stimulated nontransfected T cells. In addition, more than 90% of the transfected cells express both the CD4 and "naive" T cell marker, CD45RA. In order to investigate whether the lack of long-lived CD8+ cells reflects phenotypic restriction, separated CD4+ and CD8+ subpopulations were transfected with SV40 large T. All transfections resulted in extended life spans of CD4+, but not CD8+, cells. Therefore, although SV40 large T transfected T lymphocytes maintain normal function, while demonstrating an extended life span, the effect may be restricted to CD4+ cells.

Antigens, Polyomavirus Transforming↗

PubMed1993

Hydrocortisone regulation of interleukin-6 protein production by a purified population of human peripheral blood monocytes.

The direct effect of the endogenous glucocorticoid (GC) hydrocortisone (HC) on interleukin-6 (IL-6) production was examined using purified populations of human peripheral blood monocytes (Mo). Lipopolysaccharide (LPS) induced IL-6 production by Mo in a dose-dependent fashion. IL-6 was detected in Mo supernatants as early as 2 hr after stimulation, with peak IL-6 production observed by 16 hr. Simultaneous addition of HC and LPS resulted in a significant decrease of IL-6 production 4 hr after LPS treatment, with maximum inhibition observed at 16-24 hr. An attenuation of the inhibitory effect of HC occurred with greater concentrations of LPS and with the delay of HC addition until after LPS. However, there was no correlation between the quantity of IL-6 produced by Mo and the level of HC inhibition. The inhibitory effect of HC was greater if LPS, rather than IL-1 beta, were used as a stimulus to induce IL-6 production. The EC50 of LPS-induced IL-6 production by HC was 2.0 x 10(-7) M. The inhibitory effect of HC on LPS-stimulated IL-6 production was GC specific and receptor mediated because: (i) equivalent inhibition was not observed with other endogenous steroids and (ii) equimolar amounts of the GC antagonist RU 486 blocked the GC-mediated effect.

Adult↗

PubMed1993

Inhibition of interferon stimulation of natural killer cell activity in mice anesthetized with halothane or isoflurane.

BACKGROUND: Basal cytotoxic activity of NK cells, a subtype of lymphocytes involved in the nonspecific immune response to viruses, tumors, and some bacteria, is altered in the postoperative period. The current study examines the effects of halothane and isoflurane on interferon-induced stimulation of NK cell cytotoxicity in vivo and in vitro. METHODS: Mice were exposed to either anesthetic on days 10, 5, 1, or -1 relative to interferon treatment on day 0. NK cytotoxicity was assessed 24 h later. Similarly, splenic mononuclear cells containing NK cells were treated with interferon, before or after in vitro exposure with either halothane or isoflurane, and cytotoxicity was determined. RESULTS: In vivo, isoflurane or halothane inhibited subsequent interferon-induced NK cell stimulation (> 90% and 67%, respectively). No inhibition occurred if interferon was given before anesthetic exposure. Significant inhibition of interferon-induced NK cell stimulation could be observed 11 days after anesthesia. In vitro, both anesthetics inhibited the subsequent stimulation of NK cytotoxicity by interferon, however, cytotoxicity of NK cells treated with interferon before anesthetic exposure was comparable to untreated interferon-stimulated NK cells. CONCLUSIONS: Halothane and isoflurane inhibit interferon stimulation of NK cytotoxicity in naive (unstimulated) NK cells of the splenic mononuclear cell pool without affecting the cytotoxicity of previously stimulated (interferon) NK cells. This could occur directly by preventing the NK cell from responding or indirectly by altering other cells in the splenic mononuclear cell pool (T cells, macrophages), which then inhibit NK cell induction.

Anesthesia↗

PubMed1992

Splenic and inguinal lymph node T cells of aged mice respond differently to polyclonal and antigen-specific stimuli.

Numerous changes have been reported to occur in T cell responsiveness of mice with increasing age. However, most of these studies have examined polyclonal stimulation of spleen cells from a limited number of mouse strains. This study investigated the influence of genetic background, source of lymphocytes, and type of stimulus on age-associated changes in T cells response. Con A-induced proliferation and IL-2 and IFN-gamma production by splenic lymphocytes (SL) was significantly greater in CBA/Ca mice compared to C57BL/6 mice, regardless of age. SL of both strains exhibited the predicted age-dependent decline in proliferative response and an increase in IFN-gamma production in response to Con A. In contrast, however, only SL from C57BL/6 mice demonstrated the predicted age-dependent decline in Con A-induced IL-2 production; Con A-induced SL of young and aged CBA/Ca mice produced comparable amounts of IL-2. Differences in age-associated responses to Con A were also observed between SL and inguinal lymph node (ILN) cells of CBA/Ca mice. In contrast to SL, ILN cells demonstrated an increased proliferative response to Con A. However, lymphokine production by Con A-stimulated ILN cells from aged CBA/Ca mice was similar to that of Con A-stimulated SL from aged CBA/Ca mice. To determine if aged ILN T cells respond similarly to polyclonal and antigen-specific stimuli, keyhole limpet hemocyanin (KLH) responses of T cells isolated from ILN of aged and young CBA/Ca mice were examined. KLH-specific T cells from aged mice cultured with KLH-pulsed macrophages (M phi) from aged mice were significantly reduced in their ability to proliferate compared to KLH-specific T cells of young mice cultured with young KLH-pulsed M phi. In contrast to the expected results, the defect was not at the level of the T cells; proliferation of young T cells cultured with aged KLH-pulsed M phi was equivalent to the proliferation of aged T cells cultured with aged M phi. These results suggest that aging has differential effects on polyclonal and antigen-specific T cell proliferation and on polyclonal stimulation of T cells isolated from different lymphoid organs and from different strains of mice.

Aging↗

PubMed1992

Extension of lifespan of human T lymphocytes by transfection with SV40 large T antigen.

Lymphocytes have a finite and predictable proliferative life span in culture similar to that observed in fibroblasts. In general, the senescence of human fibroblasts is inevitable and irreversible, but their proliferative life span can be extended by certain DNA tumor virus oncogenes, such as the large T antigen of the SV40 virus. Here, we show that human T lymphocytes (HTL) can be stably transfected with SV40 large T and that expression of T antigen extended the life span of T cell cultures. PHA-stimulated HTL were transfected with pSV3neo, an expression vector containing the SV40 early region and the neomycin resistance gene. Transfectants were selected for neomycin (G418) resistance. Control HTL, either mock transfected or transfected with pSV2neo (containing the neomycin resistance gene only), ceased proliferation after about 17 population doublings. In contrast, HTL transfected with pSV3neo underwent more than 170 doublings. pSV3neo-transfected cells expressed SV40 large T RNA, detectable by in situ hybridization, and SV40 T antigen, detectable by immunofluorescence. Greater than 95% of the transfected cells were CD4 positive. These results clearly show that SV40 large T enables HTL to escape senescence. Transfection with SV40 large T may be a valuable method for obtaining long term human T cell lines for studies of both aging and immunology.

Adult↗

PubMed1992

Effect of exogenous cytokines on the inhibition of macrophage-induced, antigen-specific T cell proliferation by poly(I:C).

We have previously demonstrated that IFN-alpha/beta, poly(I:C) (an inducer of IFN-alpha/beta), or IFN-gamma can inhibit the ability of KLH-pulsed peritoneal macrophages (M phi) to induce the proliferation of syngeneic, KLH-immune T lymphocytes from CBA/J mice. In this study we investigated whether the mechanism by which poly(I:C) inhibits M phi-induced, antigen-specific T cell proliferation involved decreased cytokine production by poly(I:C) treated KLH-pulsed M phi or by T cells cultured with these M phi. The production of IL-2 by T cells cultured with poly(I:C)-treated, KLH-pulsed M phi was decreased by 80%; however, addition of exogenous rIL-2 could not restore proliferation. Although IL-1 production by poly(I:C)-treated M phi was comparable to the level produced by saline-treated, KLH-pulsed M phi controls, addition of exogenous rIL-1 was still examined to explore the possibility that a greater amount of IL-1 may be needed to induce T cell proliferation with poly(I:C)-treated, KLH-pulsed M phi. Increasing concentrations of rIL-1 alone or with rIL-6 did not abrogate the inhibition of M phi-induced, antigen-specific T cell proliferation by poly(I:C). Interestingly, the addition of combinations of IL-1 and IL-6 increased the proliferation of T cells in response to KLH presented by either saline- or poly(I:C)-treated M phi. The effect of the combination of rIL-1 and rIL-6 was synergistic in that addition of either monokine alone had no effect on T cell proliferation. These results suggest that although poly(I:C)-induced inhibition of T cell proliferation is not due to insufficient quantities of IL-1, IL-2, or IL-6, a combination of IL-1 and IL-6 can augment proliferation of freshly isolated T cells in response to antigen presented by freshly isolated accessory cells.

Animals↗

PubMed1991

Heterogeneous effects of exogenous lymphokines on lymphoproliferation of elderly subjects.

Although the ability of peripheral blood mononuclear cells of a population of elderly subjects (mean age 85.3) to proliferate in response to the T cell mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) is significantly reduced compared to young subjects (mean age 24.7), the response of the elderly subjects is heterogeneous. While 47% of the elderly subjects responded at about half the level of young controls, 15% responded at less than 20% the level and the remaining 38% responded comparably to young controls. Similar heterogeneity was observed in lymphokine production. However, there was no significant correlation between the level of proliferative response and production of either interleukin 2 (IL-2) or interferon gamma (IFN-g). In an effort to further explore the role of lymphokines in the decreased proliferative response of elderly subjects, various concentrations of exogenous IL-2 and/or IFN-gamma were added at the initiation of the mitogen stimulated cultures. Similar increases in both the level of response and the number of subjects demonstrating an increase was observed for both young and elderly subjects upon addition of either IL-2 or IFN-gamma. However, addition of a combination of IL-2 and IFN produced more pronounced effects in the elderly subjects. Approximately 1/3 of the elderly subjects who demonstrated decreased PHA-induced proliferation doubled their PHA induced proliferative response upon addition of a combination of lymphokines. The amounts of IL-2 and IFN-gamma required for this increase varied for each individual.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Role of natural killer and T-cells in interferon induced inhibition of spontaneous metastases of the B16F10L murine melanoma.

We have previously demonstrated that interferon (IFN) treatment of mice bearing the spontaneously metastasizing B16F10L murine melanoma on days -5 to -1 prior to surgical removal (day 0) of the primary tumor resulted in survival of greater than 50% of treated mice. The antitumor effect was correlated with an early increase of natural killer (NK) cell cytotoxicity followed by a later developing specific cytolytic T-cell response. The purpose of this study was to establish definitively the roles of NK, CD4, and CD8 cells as mediators of the antitumor/antimetastatic effects of IFN treatment by administration of anti-asialo-GM1, anti-L3T4, and/or anti-Lyt-2 antisera. Depletion of NK cells, alone or in combination with T-cells, eliminated the protective effect of IFN treatment. Depletion of both CD4 and CD8 cells, however, did not significantly alter the therapeutic effect of IFN therapy. Collectively, these data conclusively demonstrated the importance of NK cells as mediators of the IFN induced antitumor state. However, in mice depleted of CD4 cells alone, the protective effect of IFN was eliminated, in spite of the presence of intact NK cells. In vitro analysis of NK cytotoxicity on day 1 after surgery demonstrated (a) a lack of IFN induced stimulation of NK activity in CD4 depleted mice and (b) a significant increase in both baseline and IFN induced NK cytotoxicity in CD8 depleted mice. These data suggested a CD8 cell mediated inhibition of NK activity/stimulation in CD4 depleted mice, possibly responsible for the lack of response to IFN therapy in that group. These results demonstrate the importance of not only individual components of the immune system but also the interaction of these components in both the natural and IFN induced control of spontaneous B16F10L metastases.

Animals↗

PubMed1991

Inhibition of macrophage-induced antigen-specific T lymphocyte proliferation by poly I:C: strain and antigen independence.

We have previously demonstrated that IFN-alpha/beta, poly I:C (an inducer of IFN-alpha/beta), and IFN-gamma can inhibit the ability of KLH-pulsed peritoneal macrophages to induce proliferation of syngeneic, KLH immune T lymphocytes in CBA/J mice. In this study, we show that this IFN-induced immunosuppression is not restricted to CBA/J (H-2k) mice but is also seen in BALB/cJ (H-2d) mice. A similar inhibition of proliferation is observed with the KLH-specific T cell hybridoma BDK, 100, which requires KLH-pulsed macrophages for optimum proliferation and IL-2 production. The immunosuppression produced by IFN was also independent of the antigen employed. Inhibition of T lymphocyte proliferation was observed when casein, instead of KLH, was used to immunize T cells and to pulse peritoneal macrophages in vivo. Utilizing KLH and casein, the antigen specificity of the inhibition was demonstrated. Therefore, the inhibition by the IFN-inducer poly I:C of macrophage-induced, antigen-specific T cell proliferation is not limited by H-2 type of the mice or to one antigen.

Animals↗

PubMed1991

Inhibition of induction of natural killer activity in mice by general anesthesia (Avertin): role of interferon.

We have previously reported that general anesthesia (Avertin) inhibits the induction of natural killer (NK) cell activity following administration of Poly I:C in vivo. Since Poly I:C has been shown to increase NK activity through the induction of interferon (IFN), the current study examines the role of IFN in this inhibition. The data suggest that (i) anesthesia does not affect the ability of Poly I:C to induce endogenous IFN synthesis (serum IFN levels are unaltered by anesthesia) and (ii) anesthesia is capable of inhibiting stimulation of NK activity induced directly by treatment with IFN either in vivo or in vitro. The duration of the former effect was at least 10 days, with complete recovery by Day 14 after anesthesia. Interestingly, NK activity stimulated by IFN prior to anesthesia was not significantly altered. In view of the increasingly evident role of NK cells in anti-tumor and anti-infectious host defenses, their inertness to stimulation in the post-anesthesia period may be a significant contributing factor to the clinically observed postoperative morbidity. Thus, preanesthesia stimulation of NK activity with IFN may be of therapeutic value.

Anesthetics↗

PubMed1991

Heterogeneity of changes in lymphoproliferative ability with increasing age.

Although mean mitogen-induced lymphoproliferation decreases with increased age, the response of individual subjects demonstrates great heterogeneity. Results of this study clearly illustrate that individual variation is apparent not only in the level of proliferation, but also in the amount of interleukin-2 (IL-2) detectable after mitogen stimulation. Further, addition of exogenous IL-2 significantly increases proliferation in only about one third of elderly subjects. Data from inbred strains of rats housed under identical environmental conditions indicate that although genetic factors greatly influence both the level of proliferation and the rate of decline with age, variation occurs even within one inbred strain of rat.

Adult↗

PubMed1990

Neoadjuvant immunotherapy with interferon of the spontaneously metastasizing murine B16F10L melanoma.

We have previously demonstrated that administration of interferon a/b (IFN) for 4-5 days after challenge with a transplantable Moloney sarcoma virus-induced tumor completely inhibited tumor development. In the present study, we examined the therapeutic effects of IFN on mortality induced by metastatic dissemination of the B16F10L murine melanoma. IFN was administered at various times in relation to the surgical removal of primary tumor: days -5 to -1 prior to tumor excision (neo-adjuvant protocol), or for 5 days after tumor excision, beginning on days 1, 6 or 11 after excision of the primary tumor (adjuvant protocols). The neo-adjuvant protocol was superior to all other protocols, significantly increasing percentage survival (56% vs. 0%) and median survival time (greater than 84 days vs. 33 days) compared to untreated controls, as well as to all adjuvant protocols. In contrast, IFN treatment on days 1 to 5 after excision of the primary tumor decreased median survival time of cases compared to untreated controls (20 days vs. 33 days). Both IFN-induced inhibition and enhancement of metastatic dissemination were dose-dependent, with higher amounts of IFN producing greater inhibition or enhancement. The superior therapeutic efficacy of the neo-adjuvant IFN treatment was associated with increased spleen and lung-derived natural killer cell cytolytic activity (on days -4, 0 and 2) followed by a later (day 13) increase in lung-associated cytolytic T-cell responses.

Animals↗

PubMed1990

T-cell function in aging: mechanisms of decline.

The above sections have provided numerous facts, many of which are conflicting, regarding the changes that occur with increasing age in T lymphocytes. Although it is impossible to state with absolute certainty the alterations that are responsible for decreased proliferation of lymphocytes from elderly subjects, the following summarizes the current status of the data: 1. The interaction of T lymphocytes with foreign stimuli appears to be generally intact. 2. Changes in numbers of CD3+, CD4+, or CD8+ cells before interaction with foreign stimuli or in the density of these markers or of mitogen receptors on the surface of aged T cells have not been consistently observed. When reported to occur, the changes are not sufficient to account for the significant decrease in T-cell proliferation that occurs with increasing age. 3. A defect in the ability of the membrane interaction with foreign stimulus to signal subsequent internal events may occur, because stimulation with phorbol esters and calcium ionophore can result in increased proliferation in some elderly subjects. 4. Decreased accumulation of cytosolic calcium after stimulation of elderly T cells occurs in mice and may be a major component of the defective activation system. This defect appears to be most apparent in the "memory" T cells (T cells expressing high levels of Pgp-1), which increase in number with increasing age. Decreases in Ca++ accumulation have not been observed in humans, but this may be due to different stimuli used. Further, investigation of an increase in "memory" T cells and of their inability to mobilize Ca++ has not been done in humans and rats. 5. Decreases in mRNA for c-myc, IL-2 receptor, and IL-2 have been reported in some, but not all, species. Whether these decreases are the result of decreases in Ca++ mobilization or are independent events in unknown. 6. Decreases in membrane expression of the activation marker RL388 and of TfR have been reported. 7. Lymphokines: a. Decreases in IL-2 production occur in mice and humans, but not in rats. In individuals with decreased IL-2 production, addition of exogenous IL-2 totally restores proliferative ability in only some individuals. Changes in IL-2R expression (number or affinity) may be an additional defect. b. Decreases in IFN-gamma occur in humans, but not in mice or rats. c. No change in IL-1 occurs in any species. Genotypic effects must be considered when evaluating the preceding observations. The heterogeneity among individuals, even within an inbred strain, cannot be discounted.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗

PubMed1990

Anesthesia inhibits poly I:C induced stimulation of natural killer cell cytotoxicity in mice.

The effects of general anesthesia on the levels of baseline and inducible splenic natural killer (NK) activity of mice were examined. General anesthesia significantly inhibited the induction of NK activity by Poly I:C, while having no effect on baseline NK. Since this effect was reproduced using three different anesthetics (Avertin, ether, and Ketamine/Xylazan), the inhibition of inducible NK activity is probably due to the state of general anesthesia, rather than to the pharmacological properties of the anesthetics. Inhibition of the Poly I:C mediated induction of NK was observed for at least 4 days after anesthesia. In contrast to anesthesia alone, anesthesia with surgery significantly decreased baseline NK activity. However, the addition of surgery to anesthesia did not significantly alter the level of inhibition of NK stimulation by Poly I:C compared to anesthesia treatment alone. Experiments assessing the NK modulatory effects of surgery alone were not performed. Interestingly, neither anesthesia alone nor anesthesia with surgery were able to significantly decrease splenic NK activity that had been induced with Poly I:C prior to anesthesia. In view of the important role of NK cells in the innate immune defenses, the possible clinical applications of these results are discussed.

Anesthesia↗