Biomedical subjects

B S Wang

Publications and source records attributed to B S Wang.

At least 37 records · Page 2Linked to original sources

PubMed1995

Augmentation of the effectiveness of porcine GH with swine antibodies induced by a synthetic GH peptide.

An effort was made to evaluate the potential usefulness of a peptide vaccine in improving the growth performance of farm animals. It was previously reported that a murine PS-7.6 monoclonal antibody (mAb) which was specific to porcine GH (pGH) enhanced the growth-promoting activity of pGH in an experimental hypophysectomized rat model. Additional data from a epitope mapping study suggested that PS-7.6 mAb recognized a pGH fragment corresponding to an amino acid sequence 54-95. In this report, therefore, a peptide pGH(54-95) was synthesized in an attempt to induce PS-7.6-like antibodies in swine. It was demonstrated that the peptide pGH(54-95) competed with PS-7.6 mAb for the binding to radioactive pGH in a competition radioimmunoassay and also caused pigs to elicit polyclonal antibodies immunoreactive to pGH protein. The association and dissociation rate constants of the swine antibody to pGH were 1.9 x 10(2) M-1 s-1 and 3.2 x 10(-4)s-1 respectively, thus producing an overall binding affinity of Kd = 1.6 x 10(-6) M. The swine antibody partially competed with murine PS-7.6 mAb for the binding to pGH, suggesting that the pGH-recognizing sites for both antibodies might be closely related. The biological effect of the swine antibody was examined in hypophysectomized rats and shown to significantly augment pGH activity in promoting the growth of these GH-deficient animals. The present findings suggest that a synthetic peptide may be developed as a potential growth vaccine for swine to generate antibodies capable of enhancing the effectiveness of endogenous pGH.

Animals↗

PubMed1995

Epitope mapping and analysis of a growth-enhancing monoclonal antibody by limited tryptic digestion of porcine GH.

In this study, the epitope of a murine PS-7.6 monoclonal antibody (mAb) which was raised against the recombinant porcine GH (pGH) and subsequently shown to enhance the growth-promoting activity of pGH in a hypophysectomized rat model, was mapped by the limited tryptic digestion of pGH. A pGH fragment corresponding to amino acid residues 70-95 was separated by reverse-phase HPLC and also immunoprecipitated by PS-7.6 mAb. This fragment was found in an RIA to compete with radiolabelled pGH for the binding of PS-7.6 mAb in a dose-dependent fashion. Several peptides covering this potential epitope region of pGH(70-95) were synthesized and assayed by competitive RIA. The results suggested that pGH(75-90) was the optimal sequence recognized by PS-7.6 mAb. Sequential alanine substitution of each residue of pGH(75-90) revealed that the side chains of Leu76, Ile83 and Leu87 were critical for binding to PS-7.6 mAb. Other residues could be replaced by alanine without substantially altering the binding affinity. The region of amino acids 75-95 comprises the C-terminal end of the second helix of pGH and the repeating pattern of i and i + 3 (i + 7) of the critical amino acids appears consistent with PS-7.6 mAb binding to the hydrophobic side of the helix. The sequence and the helical structure of the epitope of PS-7.6 mAb provide the basis for designing the effective peptide vaccines to enhance the growth performance of animals.

Amino Acids↗

PubMed1994

Promotion of animal growth with a monoclonal anti-idiotype specific to anti-porcine growth hormone antibody.

A monoclonal antibody (mAb), designated PS-7.6, was previously shown to enhance the growth-promoting activity of porcine growth hormone (pGH) in an experimental hypophysectomized (hypox) rat model. The long lasting effect of PS-7.6 was postulated to be a result of the induction of anti-idiotypic antibody (anti-id) in these treated animals. An attempt was made in this report to further explore this issue. It was demonstrated that mice following immunization with PS-7.6 were capable of producing anti-id in serum. The antibody titers of mice immunized with a mixture of PS-7.6 and pGH were much higher than that of those being immunized with PS-7.6 alone. A monoclonal anti-id, designated 2A6, was generated and found to recognize the intact PS-7.6 and its F(ab')2 fragment under non-reducing condition in Western analysis. However, it did not interact with reduced PS-7.6, suggesting the necessity of both H and L chains for the expression of a conformational idiotype. In radioimmunoassay, 2A6 competed with pGH for the binding to PS-7.6, but failed to do so with a control anti-pGH mAb recognizing a distinct pGH epitope from that of PS-7.6. Results from a biospecific interaction analysis which monitored the molecular interactions in a real-time fashion confirmed the facts that 2A6 specifically recognized the variable region of PS-7.6 and that the recognition was inhibited by the presence of pGH. Enzyme-linked immunosorbent assay provided further evidence to indicate that 2A6 bound to GH binding protein, i.e. the soluble GH receptor, and pGH prevented this interaction in a dose-dependent manner. The biological effect of 2A6 was evaluated in hypox rats and shown to promote the growth of these GH-deficient animals. Taken together, the present findings clearly demonstrate that 2A6 raised against a growth-enhancing anti-pGH mAb mimics pGH both conformationally and functionally.

Animals↗

PubMed1994

Generation of heterohybridomas capable of releasing swine monoclonal antibody specific to porcine growth hormone.

An effort was made to generate stable swine hybridomas capable of releasing monoclonal antibodies (MAb) with antigenic specificity. Crossbred pigs were immunized with recombinant porcine growth hormone (r-pGH) and the splenic cells were harvested from these animals. B lymphocytes enriched by gradient centrifugation and nylon wool adherence were briefly stimulated in vitro with r-pGH prior to hybridization with murine SP2/0 myeloma cells. The fused hybrids were screened for their ability to produce anti-pGH antibody and the positive ones were subcloned by a limiting dilution procedure. The stable cell lines were maintained by serial passages in cultures for further analysis. One such hybridoma, designated PM20/20, was found to secrete swine IgM. It recognized not only the immunizing r-pGH but also the native pGH extracted from the swine pituitary glands, as demonstrated by Western analysis. It also recognized two smaller fragments with m.w. of 10 kD and 5 kD of r-pGH following trypsin digestion. In addition to pGH, PM20/20 immunoreacted with several other GH species including bovine, chicken, and human origins, but not with ovine prolactin nor rat GH binding protein. The binding association rate constant and dissociation rate constant of PM20/20 to pGH were 5.3 x 10(4) M-1 s-1 and 1.0 x 10(-4) s-1, respectively, thus producing a dissociation constant of 1.9 x 10(-9) M. Therefore, stable swine-mouse heterohybridoma lines have been established and shown to continuously release swine mAb in cultures. These mAb may serve as useful alternatives to murine mAb in certain areas of research.

Animals↗

PubMed1994

Antibody response elicited by T-dependent and T-independent antigens in gene targeted kappa-deficient mice.

Animal models substantially contribute to the understanding of the pathogenesis of various human diseases, including those associated with genetic defects. Our study investigated the characteristics of antibody responses elicited by T-dependent and T-independent antigens in mice rendered kappa-deficient by targeted deletion of the J kappa C kappa gene segments. It is known that in normal murine species the kappa repertoire dominates the antibody repertoire (kappa/lambda ratio = 95:5). Our results indicate that the kappa gene deletion causes the alternative usage of lambda 1 (93%) and lambda 2 (7%) light chains, confirming previous studies demonstrating that in kappa-deficient mice all B cells express Ig lambda receptors. The anti-trinitrophenylbenzene (TNP) response in K-/- mice was compensated for by lambda 1 and lambda 2 bearing Igs. However, isoelectric focusing analysis of anti-TNP antibodies showed a considerably more restricted pattern of lambda anti-TNP antibodies in K-/- as compared with kappa antibodies in normal mice. No major differences were observed in the affinity for the hapten of kappa or lambda 1 or lambda 2 mAbs obtained from 129/Sv and K-/- mice. Furthermore, lambda 1 and lambda 2 chains can reconstitute the expression of an idiotype (460Id) borne on kappa anti-TNP antibodies. The 460Id was detected both in polyclonal and monoclonal anti-TNP antibodies obtained from K-/- mice. Our results clearly showed that the kappa anti-TNP repertoire is compensated by the lambda repertoire even though the latter is clonally restricted in K-/- mice.

Animals↗

PubMed1994

The G gamma:A gamma ratios in the fetal hemoglobin of newborns of the Man ethnic group and their gamma-globin gene arrangements.

The G gamma:A gamma ratios of Hb F were determined in 331 newborn babies of the Man ethnic group in Liaoning Province, P.R. China, using polyacrylamide gel electrophoresis; in 27 cases they were also determined by reversed phase high performance liquid chromatography. The results showed that a high G gamma value (> 80%) was present in four cases (1.21%) and low G gamma values (30-48%) in six cases (1.81%); not a single case with the A gamma T [A gamma 75(E19)Ile->Thr] chain was found. Gene mapping analysis demonstrated that two babies with high G gamma values had the -G gamma-G gamma-/-G gamma-A gamma- (0.60%), and two others the -G gamma-AG gamma-A gamma-/-G gamma-A gamma- (0.60%) arrangements. Two of the four babies with low G gamma values were identified as -A gamma-A gamma-/-G gamma-A gamma- (0.60%) and the other two as -GA gamma-/-G gamma-A gamma- (0.60%). The genotype -A gamma-A gamma- has not been reported before in Chinese.

Asian People↗

PubMed1994

[Combined non-operative intervention for retained bile duct stones].

Basket lithotriptor, piezoelectric shock wave lithotripsy, electrohydraulic shock wave lithotripsy, and endoscopic papillosphincterotomy were used to manage respectively 10, 15, 14, and 15 patients with retained intra and extrahepatic bile duct stones that could not be removed with a Dormia basket. In these four group patients the stones ranged from 5 to 25 mm in diameter. A residual stone was fragmented with a basket lithotriptor if its diameter exceeded that of the T tube tract. Shock-wave was used when mechanical lithotripsy was unsuccessful. Endoscopic papillosphincterotomy was carried out in patients with stenosis of the sphincter, or impacted stone at the Ampulla of Vater. Combined biliary lavage, Dormia basket, and choledochoscopy after lithotripsy accelerated clearance of fragments. In these four groups, stone-free rates and reoperation rates were 90, 46.7, 85.7, and 100 percent and 10, 6.6, 14.3, and 0 percent respectively. There were no serious complications.

Adolescent↗

PubMed1993

The phylogenetic position of Taxaceae based on 18S rRNA sequences.

The evolutionary position of the yew family, Taxaceae, has been very controversial. Some plant taxonomists strongly advocate excluding Taxaceae from the conifer order and raising its taxonomic status to a new order or even class because of its absence of seed cones, contrary to the case in the majority of conifers. However, other authors believe that the Taxaceae are not fundamentally different from the rest of the conifers except in that they possess the most reduced solitary-ovule cones. To resolve the controversy, we have sequenced the 18S rRNA genes from representative gymnosperms: Taxus mairei (Taxaceae), Podocarpus nakaii (Podocarpaceae), Pinus luchuensis (Pinaceae), and Ginkgo biloba (Ginkgoales). Our phylogenetic analysis of the new sequence data with the published 18S rRNA sequence of Zamia pumila (a.cycad) as an outgroup strongly indicates that Taxus, Pinus, and Podocarpus form a monophyletic group with the exclusion of Ginkgo and that Taxus is more closely related to Pinus than to Podocarpus. Therefore, Taxaceae should be classified as a family of Coniferales. Our finding that Taxaceae, Pinaceae, and Podocarpaceae form a clade contradicts both the view that the uniovulate seed of Taxaceae is a primitive character and the view that the Taxaceae are descendants of the Podocarpaceae. Rather, the uniovulate seed of Taxaceae and that of some species of Podocarpus appear to have different origins, probably all reduced from multiovulate cones.

Base Sequence↗

PubMed1993

Inhibitory effect of growth-enhancing antibody on the interaction between growth hormone and growth hormone binding protein.

A monoclonal antibody (mAb), designated PS-7.6, was generated in mice by immunizing these animals with recombinant porcine growth hormone (pGH). This antibody has been previously shown to enhance the growth-promoting activity of pGH in an experimental rat model. An effort was made in this report to further characterize the immunologic properties of this antibody and its effect on the interaction between pGH and GH binding protein (GHBP). This antibody was classified as IgG1 isotype and found to be highly specific to pGH in a competition radioimmunoassay (RIA). It did not recognize several other GHs including those of bovine, chicken and human origins, nor several growth related factors including prolactin, insulin, somatostatin and growth hormone releasing factor. In Western analysis, PS-7.6 mAb identified not only the 22.5 kDa recombinant pGH, but also the native pGH in swine pituitary gland. An additional 45 kDa protein was also detected in the gland by the antibody, presumably a dimer form of pGH. The association and dissociation rate constants of the antibody as determined by biospecific interaction analysis (BIA) were 2.43 x 10(4) M-1 s-1 and 1.29 x 10(-3) s-1, respectively and its affinity (Kd) was 4.85 x 10(-8) M. Furthermore, PS-7.6 mAb prevented pGH from interacting with GHBP in RIA and BIA, indicating that the antibody epitope closely associated with the pGH binding region for GHBP. Therefore, present findings suggest that a possible mechanism of action of PS-7.6 mAb in enhancing animal growth is to prevent pGH from being bound to GHBP in circulation, thus making more pGH available to tissue receptors.

Animals↗

PubMed1993

Effect of murine ascites on the ability of hybridoma cells to produce antibody and proliferate in vitro.

Murine ascites has been shown to contain a variety of growth promoting activities. In this study, we examined the effects of ascites fluid on the efficiency of hybridoma production and cell growth. SP2/0 mouse myeloma cells were injected into peritoneal cavities of mice and ascitic fluid was collected. Lymphocytes from mice immunized with porcine growth hormone (pGH) were fused with myeloma cells in a standard hybridization procedure. These cells were then dispensed in 96-well plates in medium containing either 2.5% ascites or 20% fetal calf serum (FCS) and cultured for few days. Supernatants from these cultures were collected and analyzed for anti-pGH antibodies. It was demonstrated that ascites-supplemented medium increased the efficiency in generating specific antibody-secreting hybridomas by 4-fold over FCS-supplemented medium. Furthermore, hybridoma cells were cultured in microtiter plate and found to proliferate in response to ascites in a dose dependent manner. This effect was abolished by prior digestion of ascites with trypsin, indicating its protein nature. B-lymphocyte related cytokines seemed less likely involved because antibodies to IL-4 and IL-6 failed to alter the stimulatory effect of ascites. Ascites was fractionated by FPLC using Superose 12 column and the active moiety was found to be a small m.w. peptide (< 1,000 dalton). Therefore, murine ascites is capable of substituting for conventional FCS in culture medium in the area of hybridoma technology.

Animals↗

PubMed1993

Interaction of monoclonal antibodies with growth hormone-binding protein and its complex with growth hormone.

The properties of four independent lines of monoclonal antibodies (MAbs) specific to rat GH-binding protein (GHBP) were examined. Three MAbs, designated GHR-12, GHR-13 and GHR-16, were raised against the entire GHBP molecule. The fourth MAb, designated as GHBP4.3, was raised against the 17 amino acid residues at the C-terminal end of rat GHBP. The interaction of these antibodies with GHBP and their effect on GH binding to GHBP were analysed by conventional competition binding assays and surface plasmon resonance, i.e. with a Biospecific Interaction Analysis (BIAcore) instrument. The binding affinity of these MAbs to GHBP ranged from 29 nmol/l to 30.9 pmol/l. The pair-wise antibody binding to GHBP on BIAcore suggested that GHR-13 and GHR-16 recognized different antigenic determinants while part of the GHR-12 epitope might be shared with the other antibodies. The antibodies inhibited the interaction of GH with GHBP in the competition binding assay. However, in sequential binding on the BIAcore instrument, they were able to bind GHBP after its interaction with GH, indicating that the inhibition observed in the competition binding assay resulted from steric hindrance rather than direct interference with the GH-binding site of GHBP. The present findings, therefore, suggest that these antibodies are useful for investigating GHBP and its interaction with GH.

Animals↗

PubMed1993

EDAP piezoelectric shock wave lithotripsy for gallbladder stones.

EDAP piezoelectric shock wave lithotripsy combined with oral ursodeoxycolic acid dissolution of stones was used to treat 1055 patients with gallbladder stones. 926 of them (87.8%) were followed up for more than 1 year. The patients were divided into two groups: Group I, 637 patients with functioning gallbladders containing one radiolucent stone less than or equal to 20 mm in diameter or 2 to 3 stones each less than or equal to 12 mm, and Group II: 289 patients with stones exceeding the above criteria. The stone fragmentation rate was 96.2% and 94.1% respectively in Group I and in Group II. Gallbladder stones disappeared in 18.5%, 35.0%, 46.2% and 52.4% of the patients in Group I in 1, 3, 6, and 12 months after treatment and 7.3%, 11.4%, 20.1%, and 27.7% in Group II. The treatment was more effective for solitary stones less than or equal to 20 mm in diameter. No serious complications were noted. The midterm curative effect was satisfactory. Further study is required to raise the curative effect and prevent stone recurrence.

Adult↗

PubMed1992

A proposed mechanism of action of a growth hormone-specific monoclonal antibody in the enhancement of hormonal activity.

The potentiation of the biological activity of recombinant porcine growth hormone (pGH) by immunologic manipulation was investigated. An anti-pGH monoclonal antibody, designated PS-7.6, was generated and its effect on pGH was evaluated in hypophysectomized (hypox) rats. As expected, administration with pGH for 5 consecutive days promoted these animals to grow. The effect was further augmented when pGH was given together with PS-7.6 antibody and the enhancing ability of the antibody lasted beyond the treatment period. The growth profile of rats receiving antibody alone did not differ from that of untreated controls, indicating that PS-7.6 antibody by itself was not a growth stimulant. The possible mechanism of action of the antibody was investigated by analyzing blood and tissue samples of animals following injection with 125I-labeled pGH either in its free form or complexed with PS-7.6 antibody. As compared to the pGH levels in animals receiving free pGH, approximately a half pGH was released into circulation from the injection sites when it was given in a complex form. Furthermore, 2-4-fold increases in pGH deposition were also found in various tissues of animals treated with pGH-antibody complexes over that of respective tissues of animals receiving free pGH. Therefore, the present findings suggest that PS-7.6 antibody is capable of augmenting the somatogenesis of pGH and the effect is, at least in part, explainable by its ability in altering the pharmacokinetics and biodistribution of pGH in animals.

Animals↗

PubMed1992

Cellular localization of the growth hormone binding protein in the rat.

In the rat a GH-binding protein (GHBP) exists that is derived from the GH receptor gene by an alternative messenger RNA splicing mechanism such that the transmembrane and intracellular domains of the GH receptor are replaced by a hydrophilic carboxy terminus. Previous immunohistochemical studies detailing the localization of the GH receptor binding protein (BP) have used monoclonal antibodies that recognize extracellular region-specific epitopes common to both the GH receptor and GHBP. In this study we have used a monoclonal antibody (MAb 4.3) specific for the carboxy terminus of the rat GHBP to map its somatic distribution in the rat and have compared this distribution with that of a MAb recognizing both the BP and the GH receptor. A variety of tissues including the skeletal and muscular systems, the gastrointestinal tract and derivatives, the male and female reproductive systems, skin, central and peripheral nervous systems, and the 18 day gestation fetus were investigated. The distribution of GHBP immunoreactivity (MAb 4.3) was widespread and identical to that previously reported for the extracellular region of the GH receptor (MAbs 263 and 43). Immunoreactivity was both cytoplasmic and nuclear, indicating a possible role for the GHBP in intracellular function. GHBP immunoreactivity was predominantly associated with epithelial/endothelial cell subtypes and with mesenchymal elements such as muscle, chondrocytes, and osteoblasts, as previously described for the GH receptor extracellular region. We also report here the distribution of the GH receptor/GHBP in the kidney, cardiovascular, and respiratory systems. The most prominent immunoreactivity (MAbs 4.3 and 263) was associated with the distal convoluted tubules and collecting ducts of the kidney, with the epithelium and smooth muscle of the broncho-alveolar tree (including type I and II pneumocytes), with the Purkinje and myocardial fibers of the heart and with the endothelium and smooth muscle of blood vessels. Thus we have identified sites of direct GH action in the cardiovascular, renal, and respiratory systems. In conclusion, the extensive cellular distribution of the GHBP in the rat indicates physiological function(s) other than the binding of GH in plasma. Since GHBP mRNA has also been reported in a number of tissues, it may be that the GHBP is synthesized locally to mediate intracellular transport of GH and/or transcriptional regulation by GH in a variety of target tissues.

Amino Acid Sequence↗

PubMed1991

Production of a monocot-specific monoclonal antibody against acetohydroxyacid synthase and its use in the purification and characterization of the enzyme.

Acetohydroxyacid synthase [AHAS; acetolactate pyruvate-lyase (carboxylating), EC 4.1.3.18], the first enzyme unique to the biosynthesis of valine, leucine, and isoleucine, is a known target for several different chemical classes of herbicides. Antibodies required for immunological characterization of the enzyme have not been generated by the conventional method of antibody production using purified protein. Monoclonal antibodies were raised against AHAS from corn by using as immunogen a synthetic peptide representing this enzyme. This antibody immunoprecipitated the enzyme activity from corn. On a Western blot, a protein band with a molecular weight of 65,000 was detected in crude extracts of corn. Furthermore, a monoclonal antibody immunoaffinity gel was used to isolate a single protein from crude enzyme preparations that migrated at Mr 65,000 in an SDS/polyacrylamide gel. The molecular weight of this protein band is the molecular weight predicted for a plant AHAS from a cloned gene sequence. These results strongly suggest that the Mr 65,000 protein represents AHAS in corn extracts. Interestingly, the monoclonal antibody specifically recognized the enzyme from monocots and did not crossreact with AHAS from any dicot species tested. Identification of this monoclonal antibody that distinguishes monocot and dicot AHAS is significant because of a very high degree of amino acid conservation (85%) between AHAS proteins from different species.

Acetolactate Synthase↗

PubMed1991

A novel role of growth hormone and insulin-like growth factor-I. Priming neutrophils for superoxide anion secretion.

Growth hormone (GH) and the GH-dependent growth promoting peptide, insulin-like growth factor-I (IGF-I), are both potent signals for priming human and porcine polymorphonuclear neutrophils (PMN) to secrete superoxide anion (O2-). PMA, opsonized-zymosan, or FMLP could all be used as triggering stimuli to demonstrate priming by GH or IGF-I. As positive controls, IFN-gamma and LPS also primed both human and porcine PMN for enhanced O2- release. However, only the LPS-mediated enhancement was inhibited by polymyxin B, which demonstrates that the priming induced by GH, IGF-I, or IFN-gamma was not caused by LPS contamination. Furthermore, a specific antibody to GH abrogated priming induced by this molecule. In contrast to IGF-I, the closely related molecule insulin was unable to prime PMN even at pharmacologic levels. Insulin, at pharmacologic levels, antagonized the priming mediated by IGF-I but had no effect on GH priming. A mAb directed against the human IGF-I receptor blocked the enhanced secretion of O2- by human PMN that was caused by IGF-I, but not GH, indicating that neutrophil priming induced by GH was not mediated by inducing extracellular release of IGF-I. However, priming PMN by both GH and IGF-I required de novo protein synthesis, because cycloheximide completely abrogated enhanced O2- secretion that was caused by these growth factors. These data show that a classic pituitary hormone (GH), as well as its widely recognized growth promoting peptide (IGF-I), are involved in regulating an important functional activity of both porcine and human PMN. Inasmuch as GH and IGF-I have recently been demonstrated to be synthesized by leukocytes, these data support the possibility that both of these proteins could act in a paracrine fashion as cytokines to prime PMN for an enhanced respiratory burst.

Adult↗

PubMed1991

The mechanism of action of a synthetic immunomodulator, 3,6-bis(2-piperidinoethoxy)acridine trihydrochloride (CL 246,738), in natural killer cell activation in animals.

CL 246,738 is a low molecular weight, synthetic immunomodulator. The present study was done to determine the interaction among interferon (IFN), macrophages, and natural killer (NK) cells in mice following oral administration of CL 246,738. Splenic NK activity as evidenced by lysis of YAC-1 lymphoma cells in vitro was found to be augmented by the compound not only in normal mice, but also in immunodeficient beige and nude mice. Lytic activity remained elevated from one to seven days after a single treatment and the peak activation varied depending on the source of NK cells. NK cell activity associated with the peritoneal exudate cell population peaked at day 1 and returned to normal by day 2, whereas NK cell activity of peripheral blood lymphocytes peaked at day 3 and remained significantly elevated until day 7. Liver associated NK activity peaked at day 4 and remained significantly elevated at day 7 after treatment with CL 246,738. Lung associated NK activity was elevated by day 1 after treatment, peaked at day 4 and returned to normal by day 7 after drug administration. The drug was also effective in inducing IFN in all mouse strains tested. When these drug-treated mice were given antibody to IFN-(alpha + beta) but not to IFN-(beta), both IFN levels and NK cell activity decreased, suggesting the importance of IFN-(alpha) in this system. Furthermore, mice that had received carrageenan prior to, but not after CL 246,738 administration showed reduced serum IFN titers as well as decreased NK cell activity, indicating that macrophages played an intermediate role in immune enhancement by the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Acridines↗

PubMed1991

Depression of cell-mediated immunity in plasmacytoma-bearing mice.

Previous reports have documented that mice bearing plasmacytomas (PC) are suppressed in their ability to mount a primary antibody response, whereas cellular immunity appears to be normal. Studies presented here provide evidence that T cell responsiveness is also depressed in BALB/c mice bearing the Lieberman plasmacytoma (Lpc-1). For instance, splenocytes from mice bearing large tumours were impaired in their in vitro ability to respond to the T cell mitogen, mount an appropriate alloreactive cytolytic T lymphocyte response, and produce interleukin-2 (IL-2). A population of suppressor cells was detected in the spleens 7 days after tumour implantation as evidenced by their ability to prevent normal splenocytes not only from responding to antigens in mixed lymphocyte culture, but also from producing IL-2. A similar inhibitory effect was observed with culture supernatants of these cells, indicating the existence of a soluble suppressive factor. Therefore, the present study demonstrates that cellular immune responses are impaired in mice bearing Lpc-1 tumours and that this effect may be due to the generation of suppressor cells and/or a suppressive factor.

Animals↗