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T W Klein

Publications and source records attributed to T W Klein.

At least 109 records · Page 6Linked to original sources
PubMed1990

Age-related suppression of murine lymphoid cell blastogenesis by marijuana components.

Marijuana components modulate a variety of immune response parameters. The cannabinoids delta 9-tetrahydrocannabinol (THC) and 11-hydroxy-tetrahydrocannabinol (11 OH-THC) are known to depress the in vitro proliferative response of murine lymphoid cells to the mitogens concanavalin A (Con A) and phytohemagglutinin (PHA). In the present report the effects of THC and 11 OH-THC on adult thymus and spleen cells were compared to effects on lymphoid cells of those organs from juvenile mice at various ages. The results demonstrate differences in susceptibility to cannabinoid-induced suppression by lymphoid cells from different organs and different age mice. In adults, thymus cells were suppressed more readily than spleen cells. Splenocytes from mice under 2 weeks old were suppressed much more readily than those from older mice. Cell populations from organs with higher proportions of L3T4+/Lyt2- cells were more difficult to suppress. The possible mechanisms involved and directions for future work are discussed.

Age Factors↗
PubMed1990

Differential suppression of T-cell subpopulations by thc (delta-9-tetrahydrocannabinol).

THC (delta-9-tetrahydrocannabinol), the major psychoactive component of marijuana, has been shown to suppress various immune functions in vivo and in vitro. THC suppresses murine T-lymphocyte proliferation; however, the effects on T-cell subsets remain unclear. We have stimulated cultured murine splenocytes with the mitogens concanavalin A (Con A) or phytohemagglutinin (PHA) while exposing them to varying concentrations of THC. After three days, the cells were analyzed by the fluorescent activated cell sorter for the following T-cell markers--Thy1, L3T4 and Ly2. The Ly2 cells represent the suppressor/effector T-cells while L3T4 cells represent the helper T-cell subpopulations. The results show that the dose response suppressive effect of THC on T-cell proliferation reflects a preferential inhibition of Ly2 vs L3T4 cells. The effects of THC on other functional parameters are in the process of investigation.

Animals↗
PubMed1990

Alteration of rat splenocyte blastogenesis and interleukin-1 production following slow infusion of human tumor necrosis factor-alpha.

The bolus injection of tumor necrosis factor (TNF)/cachectin into rats has been reported to induce shock and tissue injury similar to catabolic states seen in cachexia. In the present study, we administered TNF/cachectin to rats by either bolus injection or slow infusion and analyzed the influence on splenocyte mitogen-induced proliferation and interleukin-1 (IL-1) production. Also, TNF administration was compared with lipopolysaccharide (LPS) injection and saline injection. Serum TNF levels were elevated by 30 min following the start of slow infusion, peaked at around 90 min, and remained elevated throughout the 3-h sampling. However, analysis of serum TNF following a bolus injection showed that TNF peaked earlier (30 min) but then declined over the next 2.5 h. LPS infusion resulted in a serum TNF peak at 60-90 min with a rapid decline to near baseline by the end of the 3-h sampling. Spleens were removed from rats following either 3 h of infusion or 3 h following bolus injection, and single-cell suspensions were prepared and analyzed in culture for lymphocyte proliferation to either concanavalin-A (con-A) or pokeweed mitogen (PWM). Adherent spleen cell cultures were also tested for IL-1-forming capacity in response to LPS. The slow infusion of TNF had a suppressive effect on splenic T lymphocyte responsiveness to con-A. This suppressive effect was not observed in the response to the T cell-dependent B cell mitogen PWM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Induction of interferon-gamma and tumor necrosis factor by Legionella pneumophila: augmentation of human neutrophil bactericidal activity.

We have previously reported that Legionella pneumophila antigens can induce interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) in vitro and in vivo in mice. Furthermore, treatment of murine polymorphonuclear leukocyte (PMN) cultures with these cytokines resulted in augmented killing of the bacteria in vitro. The purpose of the present study was to determine if these findings could be extended to human responses. Here we report that Legionella antigens induced IFN-gamma and TNF in nonimmune human leukocytes cultures, and that these cytokines were able to stimulate the bactericidal activity of isolated PMN against L. pneumophila in vitro. Furthermore, optimal production of IFN-gamma was found in cultures which were enriched for large granular lymphocytes (LGL). The phenotype of IFN-producing cells was determined to be CD11+, CD16+, CD2+, and negative for CD4, CD8, CD14, and Leu 7. Additionally, Legionella-infected monocytes were found to produce TNF in a dose-dependent response to the number of infecting bacteria, and the addition of recombinant IFN-gamma to infected monocytes resulted in augmented production of TNF in a synergistic manner. Finally, treatment of PMN with recombinant IFN-gamma and recombinant TNF augmented their bactericidal activity against Legionella in a dose-dependent response. Thus, cytokines which can be induced by L. pneumophila antigens are able to stimulate PMN function in vitro, suggesting that resistance to infection results from a complex interaction of cytokines and cell responses.

Antibodies↗
PubMed1989

Induction of interleukin 1 by Legionella pneumophila in murine peritoneal macrophage cultures.

Legionella pneumophila-induced production of both membrane-associated and secreted interleukin 1 (mIL-1 and sIL-1, respectively) was examined utilizing peritoneal macrophages from BALB/c mice. The Legionella preparations for these studies included viable bacteria and formalin-killed whole cell preparations. Both of the preparations induced mIL-1 and sIL-1 in a dose-dependent fashion. However, the viable bacteria required about 1 log lower concentrations than the formalin-killed bacteria to induce the same level of IL-1 activity measured in the thymocyte proliferation assay. Kinetic studies showed that mIL-1 and sIL-1 were detectable within 4 hr after addition of either of the L. pneumophila preparations to the peritoneal macrophage cultures, with peak levels achieved within 24 hr. These results indicate that L. pneumophila is a potent inducer of both mIL-1 and sIL-1 in normal mouse peritoneal macrophage cultures.

Animals↗
PubMed1988

Protective effects of tumor necrosis factor in experimental Legionella pneumophila infections of mice via activation of PMN function.

Tumor necrosis factor (TNF) was found in the lung lavage fluids of Legionella pneumophila-infected mice within 24 hr of intratracheal (i.t.) inoculation. Since this cytokine has been reported to activate polymorphonuclear leukocyte (PMN) function, the effect of TNF on the in vitro bactericidal capacity of PMN-enriched cultures was determined. Murine thioglycollate-elicited PMN which were treated with recombinant human TNF demonstrated augmented killing of L. pneumophila bacteria in vitro. Furthermore, treatment of PMN suspensions with cytokine-containing lung lavage fluid was found to enhance the bactericidal activity of PMN. The addition of anti-cachectin/TNF antibodies partially abrogated the stimulatory effects of the lavage fluid, suggesting that in vivo activation of PMN during the course of infection was likely, and that TNF was partially responsible for the enhanced bactericidal activity. In vivo treatment of animals with TNF resulted in significant protection of the animals from mortality. Furthermore, the rate of clearance of bacteria from the lung tissues of infected mice was increased in those animals treated with TNF, and correlated with the ability of this cytokine to protect the animals. These data suggest that the induction of TNF by Legionella bacteria during infection are involved in the non-specific host defense mechanisms, and that PMN activated by the TNF may be instrumental in clearing the organism from infected lung tissues, thereby protecting the animal.

Animals↗
PubMed1988

Legionella pneumophila immunity and immunomodulation: nature and mechanisms.

L. pneumophila is a facultative intracellular opportunistic pathogen ubiquitously present in the environment. Much is now known concerning the ecological niche of this organism as well as many other characteristics of these bacteria, including physiology and biochemistry. However, much less is known about immune mechanisms responsible for host resistance vs susceptibility. Not only outer membrane protein rich fractions but also LPS-rich components are potent immunogens, both in experimental animals such as susceptible guinea pigs and more resistant rodent species like rats and mice. Immunity to these organisms can be readily observed by a variety of serologic techniques. Antibody titers increase rapidly after exposure of individuals to these bacteria either by infection or immunization. However, such antibody does not appear to play an important role in host resistance. Serum antibody plus complement is not lytic for the bacteria in vitro. Furthermore, antibody appears to promote the phagocytosis of the bacteria by monocytes and/or macrophages in culture but such phagocytosis does not result in killing of the bacteria, merely an enhanced uptake and subsequent replication of the organisms. Studies on cellular immunity have focused attention on the role of T lymphocytes, monocytes and macrophages. In addition, cutaneous hypersensitivity is readily induced by infection or immunization of experimental animals with Legionella or antigenic components. In vitro correlates of hypersensitivity is also readily evident after infection or immunization. Although lymphoid cells from guinea pigs only show evidence of responsiveness to Legionella antigens by the lymphocyte blastogenic reaction after animals have been sensitized, peripheral blood monocytes from man as well as splenocytes from mice show evidence of responsiveness to Legionella even before known infection or sensitization. However, higher blastogenic responses become evident after sensitization or infection. In addition, interleukins, such as interleukin 1 and 2, as well as interferon and tumor necrotizing factor, appear in response to Legionella antigens and seem to play a role in resistance mechanisms. Cellular replication of Legionella in monocytes from man as well as macrophages from susceptible animals seems related to susceptibility or resistance to these organisms. Further analyses of the nature and mechanism of humoral vs cellular immune responses to Legionella antigens will provide valuable information about immunity and resistance to these intracellular pathogens in susceptible individuals.

Animals↗
PubMed1988

Suppression by delta-9-tetrahydrocannabinol of interleukin 2-induced lymphocyte proliferation and lymphokine-activated killer cell activity.

The major psychoactive marijuana component, delta-9-tetrahydrocannabinol (THC), suppressed proliferation of murine spleen cells stimulated with recombinant human interleukin 2 (IL-2) and also suppressed the appearance of the lymphokine-activated killer (LAK) cell phenomenon in IL-2-treated spleen cell preparations. Cell function was depressed in a dose-dependent manner with as little as 2.5 micrograms/ml THC (8 microM). In addition, spleen cells previously stimulated in culture with IL-2 and then incubated with THC for 4 h prior to target cell addition, displayed suppressed cytolytic activity against both YAC-1 and EL-4 tumor targets. Killing of EL 4 cells was suppressed at lower drug doses than the killing of YAC-1 targets. These results suggest that THC can suppress several important functions of IL-2 including clonal expansion of lymphocytes, expansion of killer cell populations and stimulation of killer cell cytotoxic activity.

Animals↗
PubMed1988

Growth of Legionella pneumophila in thioglycolate-elicited peritoneal macrophages from A/J mice.

Legionella pneumophila is a facultative intracellular bacterium which readily grows in cultures of guinea pig and human mononuclear phagocytes. In this report, we demonstrate that the Legionella sp. also grows in thioglycolate-elicited macrophages obtained from A/J mice but not in cells from other mouse strains tested, such as BDF1, DBA/2, C3H/HeN, C57BL/6, and BALB/c. Growth of Listeria monocytogenes and interleukin-1 production in A/J mice were similar to their growth and production in other strains tested, and the growth of Staphylococcus epidermidis was restricted by A/J macrophages. This finding suggests that although A/J macrophages share functional capabilities with cells from other mouse strains, they differ in growth restriction capacity for the Legionella sp. Resident macrophages were less permissive than were thioglycolate-elicited cells in that resident cells from A/J mice failed to support the growth of Legionella pneumophila. Also, resident cells from BDF1 mice rapidly eliminated the bacteria, rather than merely restricting growth. This finding was also observed in in vivo studies in which thioglycolate pretreatment of mice resulted in the enhanced recovery of viable bacteria from the peritoneal cavity of mice infected intraperitoneally. Higher numbers of bacteria were obtained from A/J mice and, in addition, this strain was more susceptible to the lethal effects of Legionella infection. These data suggest that, as with other intracellular bacteria, macrophages may serve a pivotal role in the early stages of Legionella infection and further suggest that the A/J mouse represents a useful animal model for the study of Legionella infection and immunity.

Animals↗
PubMed1988

Role of gamma interferon in induction of natural killer activity by Legionella pneumophila in vitro and in an experimental murine infection model.

Legionella pneumophila has been shown to induce gamma interferon (IFN-gamma) both in vitro and in vivo during experimental infections of mice. With complement-mediated serologic depletion of murine splenocytes, the cellular sources of IFN-gamma following in vitro stimulation with L. pneumophila antigens were Thy-1.2+, Lyt-2-, L3T4-, and asialo-GM1+, which is consistent with the natural killer (NK) cell phenotype. Additionally, Percoll density discontinuous centrifugation demonstrated that maximal production of IFN coincided with high NK activity in fractions which were enriched for large granular lymphocytes. Furthermore, 18- to 24-h incubation of splenocytes with L. pneumophila whole-cell vaccine resulted in augmented NK cytotoxic activity against YAC-1 tumor target cells in a 51Cr release assay. The addition of macrophages to purified large granular lymphocyte populations augmented both IFN-gamma production and NK activity, suggesting that antigen is required for optimal responses. In an experimental infection model using an intratracheal inoculation route, NK activity was enhanced in the spleen, peripheral blood, and lung cells of infected mice, with maximal stimulation in the lung leukocytes at the site of infection. The results of the present study indicate that NK cells respond in vivo and in vitro to stimulation by L. pneumophila by producing IFN-gamma and by increased cytolytic activity.

Animals↗
PubMed1988

Suppression by cannabinoids of a cloned cell line with natural killer cell activity.

Preincubation of a cloned cell line with natural killer (NK) cell activity, as well as splenic mononuclear cells with either delta 9-tetrahydrocannabinol (THC) or 11-hydroxy-delta 9-tetrahydrocannabinol (11-OH-THC) suppressed NK cytolytic activity against YAC-1 target cells in a dose-dependent manner. THC was more inhibitory for cloned cells than 11-OH-THC and suppressed the lytic activity of these cells without reducing cell viability in the concentration range of 5 micrograms/ml (16 microM) to 10 micrograms/ml (32 microM). THC also inhibited proliferation of cloned NK cells, but this inhibitory effect was reversible in that extensive washing of cells following cannabinoid pretreatment eliminated the suppressive effect. Single-cell analysis revealed that THC did not inhibit the binding of cloned NK cells to target cells and further showed that NK cells freshly isolated from mouse spleen were restricted in killing capacity following binding to target cells. Therefore, THC and 11-OH-THC appear to directly inhibit NK cell cytolytic activity in a postbinding stage.

Animals↗
PubMed1987

Cytolytic activity of human peripheral blood leukocytes against Legionella pneumophila-infected monocytes: characterization of the effector cell and augmentation by interleukin 2.

The present study was an in vitro attempt to define the effector mechanisms against the intracellular bacterium Legionella pneumophila. Monocytes from human peripheral blood leukocytes (PBL) were infected in vitro with L. pneumophila and cultured for 2 days to allow intracellular replication of the bacterium. Cells were then labeled with 51Cr and used as targets in a 4-h 51Cr-release assay. We report here that autologous nonadherent PBL effectively lysed infected monocytes, and this activity was enhanced when the effector cells were precultured with IL 2 for 2 days. The IL 2-activated killer cells were also cytolytic against uninfected cultured monocytes, but cytotoxicity was higher against Legionella-infected target cells in a dose-dependent manner. The effector cells were located in Percoll density fractions that were enriched for large granular lymphocytes. The phenotype of the effector cell activated by IL 2 was determined to be OKM1+, OKT11+, partially Leu-11+, and negative for Leu-M1, OKT4, OKT8, and Leu-7, indicating that it is neither a T cell nor a monocyte, and is possibly and NK subset that is Leu-11+ and Leu-7-. Cold target inhibition studies indicated that a similar recognition structure is shared by both infected and uninfected monocytes, but differs from that on K562 tumor target cells. Thus, in addition to tumor surveillance and controlling viral infections, killer cells can be activated to provide protection against intracellular bacterial infections.

Antibodies, Monoclonal↗
PubMed1987

Modulation of carrier-induced epitopic suppression by Bordetella pertussis components and muramyl peptide.

Synthetic antigens employed in experimental synthetic vaccines are generally small haptenic peptides. Therefore, effective immunization with these antigens usually requires the use of an immunogenic carrier. Tetanus toxoid has been proposed for use as a carrier in future synthetic vaccines due to its high immunogenicity and acceptance for human use. Previous studies employing standard hapten/carrier systems such as DNP/KLH have demonstrated, however, that an epitope-specific suppression occurs when mice previously primed with carrier are subsequently immunized with an haptenic epitope conjugated to the same carrier. These same studies have shown that Bordetella pertussis vaccine administered at the time of carrier priming abrogates epitopic suppression. In the present investigation, epitopic suppression was studied in a synthetic vaccine model employing tetanus toxoid as a carrier. Results from these studies indicated that mice primed with tetanus toxoid 1 month before immunization with a peptide-tetanus toxoid conjugate exhibited enhanced secondary anti-tetanus toxin responses but decreased anti-peptide responses. Furthermore, injection of pertussis vaccine or purified B. pertussis toxin or endotoxin at the time of carrier priming could block the establishment of epitopic suppression. Administration of B. pertussis components enhanced antibody responses to both the carrier and the synthetic peptides as compared with responses of control animals. In addition, administration of an adjuvant-active nonpyrogenic derivative of muramyl dipeptide. Murabutide, with carrier priming reduced epitopic suppression of anti-peptide responses. B. pertussis toxin or endotoxin administered to mice previously suppressed by carrier priming with the first injection of carrier-peptide conjugate overcame epitopic suppression with resultant titers of anti-peptide antibody equal to or greater than nonsuppressed controls. These results suggest that the use of adjuvants with future synthetic vaccines may contribute the additional advantage of overcoming epitopic suppression, thus permitting the use of common, well-tolerated carrier systems such as tetanus toxoid in synthetic vaccine preparations.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Age-associated differences in cannabinoid-induced suppression of murine spleen, lymph node and thymus cell blastogenic responses.

The effects of delta 9-tetrahydrocannabinol (THC) and 11-OH THC on the proliferative responses of murine thymus, spleen and lymph node cells were examined. Specifically, weanling and adult mouse lymphocytes were stimulated in vitro with the T-cell mitogens concanavalin A and phytohemagglutinin. Thymus cells were suppressed at lower cannabinoid concentrations than cells from either spleen or lymph nodes. However, splenic cells from weanling mice were much more readily suppressed than were those from adult animals. Lymphoid cell numbers were varied from 1 x 10(6) to 8 x 10(6) cells/ml/culture and treated with a constant dose of THC or 11-OH THC. The smallest number of cells from the spleen or lymph nodes resulted in the greatest suppression. Thymus cells, however, were more readily suppressed than spleen or lymph node cells, regardless of the number of cells in culture. Furthermore, 11-OH THC suppressed the responses of the thymus cells to phytohemagglutinin more than to concanavalin A. The proliferative responses of spleen and lymph node cells from weanling mice to concanavalin A and phytohemagglutinin were much more readily suppressed than were cells from adult mice. This age-related difference was seen in the dose-response studies as well as in the studies with varying cell numbers in culture. In all cases, spleen and lymph node cells from younger mice were more readily suppressed to concanavalin A and phytohemagglutinin than those from older mice when treated with the cannabinoid preparations.

Age Factors↗
PubMed1987

Induction of interleukin 1 by Legionella pneumophila antigens in mouse macrophage and human mononuclear leukocyte cultures.

Exposure to Legionella pneumophila antigens has been reported to result in both an adjuvant effect and pathophysiological changes such as fever, headache, myalgia and arthralgias. Immunoenhancement and inflammatory changes have been associated with the production of interleukin 1, and we, therefore, sought an involvement of interleukin production in the alteration of biological responsiveness following exposure to Legionella pneumophila antigens. Killed Legionella pneumophila cells, incubated with mouse splenocytes, induced the formation of a soluble substance which enhanced splenocyte antibody production to heterologous antigen. The immunoenhancing substance was also produced by mouse peritoneal macrophages and supernatants from these cultures were demonstrated to also contain thymocyte co-mitogenic activity. Following gel filtration, this co-mitogenic activity eluted in the 15,000 molecular weight range suggesting an involvement of interleukin 1. Experiments with Legionella pneumophila cells, and cell extracts containing endotoxin, and purified endotoxin suggested that the interleukin 1 activity was induced by both endotoxin and non-endotoxin antigens. The Legionella pneumophila antigens were also found to be potent inducers of interleukin 1 activity in human peripheral blood mononuclear cell cultures. These results suggest that Legionella pneumophila antigens are potent inducers of interleukin 1 in both mouse and human cells. The induction of this monokine may partially account for both the immunoenhancing property of this bacterial species and the associated pathophysiological changes following infection with this microorganism.

Animals↗