Secondary structure of an antibacterial peptide Abp3 studied by two-dimensional proton-NMR

An antibacterial peptide Abp3, an analogue of cecropin B, was investigated by two-dimensional proton-NMR at pH 5.0 in aqueous solution with 15% (v/v) hexafluoroisopropanol. The peptide, which consists of 35 amino acids, was synthesized chemically. Most resonances of the main-chain and side-chain protons were assigned. Several medium range NOE connectivities were observed, showing two separate alpha-helices with one amphiphilic in N-terminal domain (residues 5-21) and the other hydrophobic in C-terminal domain (residues 25-35) and a hinge region between them. The J coupling constants and the chemical shifts in these sections also supported the conclusion.

Immunosuppressive effects of FTY720 alone or in combination with cyclosporine and/or sirolimus

BACKGROUND

We examined the ability of FTY720, a novel immunosuppressant that prolongs the survival of allografts in experimental animal models, to potentiate the immunosuppressive effects of cyclosporine (CsA) and/or sirolimus (SRL) in vitro and in vivo.

METHODS

FTY720 alone (10-5000 ng/ml) or in combination with other drugs was added to human peripheral blood lymphocytes (PBLs) undergoing stimulation in vitro with phytohemagglutinin (PHA) or OKT3 monoclonal antibody. The combination index (CI) values were calculated to evaluate the nature of the interactions between FTY720 and CsA and/or SRL: CI values <1 reflect synergistic, CI=1, additive, and CI>1, antagonistic interactions. In addition, Wistar Furth (RT1u) rat recipients of Buffalo (RT1b) heart allografts were treated with FTY720 alone or in combination with other agents. FTY720 alone was also tested to block small bowel or liver allograft rejection in rats.

RESULTS

FTY720 alone produced only modest inhibition of the proliferation of human PBL stimulated with PHA or OKT3 monoclonal antibody. In combination with CsA or SRL, however, FTY720 produced synergistic effects, namely, CI values of 0.58 and 0.36, respectively. A 14-day course of FTY720 (0.05-8.0 mg/kg/day) by oral gavage prolonged heart allograft survival in dose-dependent fashion. Although a 14-day oral course of CsA (1.0 mg/kg/day) alone was ineffective (mean survival time=7.0+/-0.7 vs. 6.4+/-0.6 days in treated vs. untreated hosts), treatment with a combination of 1.0 mg/kg/day CsA and 0.1 mg/kg/day FTY720 extended allograft survival to 62.4+/-15.6 days (P<0.001; CI=0.15). Similarly, a 14-day oral course of 0.08 mg(kg/day SRL alone was ineffective (6.8+/-0.6 days; NS), but the combination of SRL with 0.5 mg/kg/day FTY720 extended the mean survival time to 34.4+/-8.8 days (CI=0.28). The CsA/SRL (0.5/0.08 mg/kg/day) combination acted synergistically with FTY720 (0.1 mg/kg/day) to prolong heart survivals to >60 days (CI=0.18).

CONCLUSIONS

FTY720 potentiates the immunosuppressive effects of CsA and/or SRL both in vitro (by inhibiting of T-cell proliferative response) and in vivo (by inhibiting allograft rejection).

Modulation of Neisseria gonorrhoeae susceptibility to vertebrate antibacterial peptides due to a member of the resistance/nodulation/division efflux pump family

We have previously described the antibacterial capacity of protegrin-1 (PG-1), a cysteine-rich, cationic peptide from porcine leukocytes, against Neisseria gonorrhoeae. We now report genetic and biochemical evidence that gonococcal susceptibility to the lethal action of PG-1 and other structurally unrelated antibacterial peptides, including a peptide (LL-37) that is expressed constitutively by human granulocytes and testis and inducibly by keratinocytes, is modulated by an energy-dependent efflux system termed mtr. These results indicate that such efflux systems may enable mucosal pathogens like gonococci to resist endogenous antimicrobial peptides that are thought to act during infection.

Mechanisms of insulin resistance and new pharmacological approaches to metabolism and diabetic complications

1. Resistance to insulin-mediated glucose transport and metabolism has been identified as a primary mechanism in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) and as a target for drug development. The aetiology of insulin resistance is likely to be multifactorial, but the present review focuses on candidate post-receptor mechanisms of insulin resistance, particularly protein kinase C (PKC), and the metabolic and genetic significance of beta3-adrenoceptors (beta3-AR) in adipose tissue. 2. Multiple lines of evidence suggest that isoform-selective activation of PKC phosphorylates and down-regulates one or more substrates involved in glucose transport and metabolism (e.g. glycogen synthase and the insulin receptor) and recent studies have shown increased expression of calcium-independent isozymes (PKC-epsilon and PKC-theta) in the membrane fraction of skeletal muscle in fructose- and fat-fed rat models of insulin resistance. In addition, there is separate evidence that glucose-induced PKC activation plays an important role in the micro- and macrovascular complications of diabetes. 3. New pharmacological approaches to NIDDM and obesity have focused on insulin-sensitizing agents (e.g. troglitazone), beta3-AR agonists, anti-lipolytic drugs (e.g. the adenosine A1 receptor agonist GR79236) and selective inhibitors of PKC isoforms (e.g. the inhibitor of PKC-beta LY333531). Experimental studies with GR79236 show that this drug ameliorates the hypertriglyceridaemia induced by fructose feeding and that the reduction in fatty acid levels is associated with secondary improvements in glucose tolerance. 4. Recent insights into the pathogenesis of NIDDM and its associated complications have been used to develop a range of new therapeutic agents that are currently showing promise in clinical and preclinical development.

[Measurement of contraction force of pilot's neck muscles]

In order to discuss the function of contraction force of pilot's neck region. Contraction force of pilot's neck region was measured in 22 volunteers aged 18-35 years. The mean contraction force is 102-396 N, the mean contraction time is 28 s. Authors think that training for pilot's neck muscular power is essential.

Sirolimus in transplantation

Although sirolimus (SRL) alone was very effective in rodents and pigs, it produced toxic side effects in dogs. Low doses of SRL combined with cyclosporine/brequinar (CsA/BQR) combinations achieved potent immunosuppression in the CsA-resistant mouse model. Similarly, SRL/CsA/BQR therapy protected kidney allografts from rejection in dogs without producing toxic side effects. In the CsA-sensitive rat model SRL/CsA combinations produced a potent synergistic interaction. In addition, recent clinical trials document the beneficial effects of low SRL doses in human kidney transplant recipients. Sirolimus, when combined with standard immunosuppressive therapy, remarkably reduces the incidence of acute rejection and permits individual drug dose reduction.

Short-term metabolic and haemodynamic effects of GR79236 in normal and fructose-fed rats

The adenosine (A1) receptor agonist, GR79236 (N-[(1S,trans)-2-hydroxycyclopentyl]adenosine), inhibits catecholamine-induced lipolysis in vitro, but the short-term metabolic and haemodynamic effects have not been previously reported in the fructose fed model of insulin resistance, dyslipidaemia and hypertension. This study reports the effects of GR79236 (1 mg/kg/day for 8 days) on nonesterified free fatty acid and triglyceride metabolism, oral and i.v. glucose tolerance, blood pressure and heart rate, and insulin sensitivity, in normal rats and rats fed a fructose-enriched diet. In normal rats, GR79236 significantly reduced fasting glucose (25%), free fatty acid (50%) and triglyceride (55%) concentrations, and improved glucose tolerance (AUC[glu] 21.2 +/- 1.3 vs. 16.5 +/- 1.1 mmol h/l, p < 0.05). Fructose feeding induced a state of insulin resistance and dyslipidaemia, as shown by an increase in steady-state plasma glucose levels (7.1 vs. 6.1 mmol/l), impaired i.v. glucose tolerance and a 3-fold rise in fasting triglyceride levels; fructose-fed rats also developed a significant increase in blood pressure. GR79236 ameliorated the effects of fructose feeding on fatty acid and triglyceride levels, and blood pressure, and improved i.v. glucose tolerance in fructose-fed rats. The hypotriglyceridaemic effect was due to a reduction in triglyceride secretion rate (17.3 +/- 1.7 vs. 30.2 +/- 1.1). Thus, in normal rats and in a dietary-induced rodent model of insulin resistance, dyslipidaemia and hypertension, GR79236 has lipid-lowering and glucose-lowering activity, as well as haemodynamic effects, which are potentially useful for treating both the metabolic and haemodynamic features of insulin resistance and NIDDM in humans.

Cytokine mRNA expression in tolerant heart allografts after immunosuppression with cyclosporine, sirolimus or brequinar

We sought to examine the impact of the preferential activation of Th2 cells on the induction and maintenance of a tolerant state in heart allograft rat recipients treated with a short course of cyclosporine (CsA), sirolimus (SRL) or brequinar (BQR). A quantitative polymerase chain reaction (PCR) method was used to measure the levels of cytokine mRNAs, namely interferon (IFN)-gamma and interleukin (IL)-2 in T helper 1 (Th1) cells and IL-4, IL-5 and IL-10 in Th2 cells. Our main findings were that on day 5 postgrafting allografts from untreated recipients had increased levels of IFN-gamma (216 +/- 119 fg), IL-2 (449 +/- 75 fg), IL-4 (6.2 +/- 1.3 fg), IL-5 (34.8 +/- 9.3 fg) and IL-10 (1554 +/- 184 fg) mRNAs compared with normal hearts. CsA reduced the levels of IFN-gamma, IL-2, IL-5 and IL-10, but not IL-4, mRNAs. SRL did not affect the expression of cytokine mRNAs. BQR decreased the levels of IFN-gamma, IL-2 and IL-10, but not IL-5 or IL-4 mRNAs. Compared with grafts from untreated recipients, those from CsA- or BQR-treated tolerant hosts (day 100) displayed undetectable IL-2 mRNA levels, and reduced levels of IFN-gamma, IL-4 and IL-10 mRNAs. In fact, the patterns of cytokine mRNA expression in grafts from CsA- and BQR-treated tolerant hosts were similar to those of normal hearts. Grafts from SRL-treated tolerant hosts merely showed slightly increased Th2 cell activity. In conclusion the selective activation of Th2 cells is not absolutely required for induction or maintenance of tolerance.

Is insulin resistance in the spontaneously hypertensive rat related to changes in protein kinase C in skeletal muscle?

The mechanism of insulin resistance in the spontaneously hypertensive rat (SHR) has not been clearly identified, but protein kinase C (PKC) has been implicated as a mechanism of insulin resistance in obesity and diabetes mellitus and in a diet-induced (fructose-fed) model of insulin resistance and hypertension. This study compared PKC enzyme activity (cytosol and particulate fractions) and expression of the muscle-specific isoform, PKC-theta (Western blotting), in red (soleus) and white (tensor fascia latae) hindlimb muscles from SHR (n = 12) and WKY (n = 12) rats. SHRs were hypertensive and insulin resistant, as shown by higher insulin (188 +/- 34 v 169 +/- 22 pmol/L), triglycerides (1.65 +/- 0.07 v 1.38 +/- 0.06 mmol/L), and nonesterified fatty acids (0.99 +/- 0.05 v 0.78 +/- 0.04 mmol/L) concentrations. PKC activity was significantly greater in the membrane fraction, compared with the cytosol, but there were no significant differences either in PKC activity or subcellular distribution, or expression of PKC-theta, between the two strains. Thus, insulin resistance in the SHR (in contrast to the fructose-fed dietary model of insulin resistance and hypertension) is not related to changes in PKC signaling or expression of PKC-theta in skeletal muscle.

P-selectin-deficient mice are protected from PAF-induced shock, intestinal injury, and lethality

In a previous study, we showed that anti-CD11b or anti-CD18 antibody markedly attenuated platelet-activating factor (PAF)-induced shock and intestinal necrosis in rats, whereas anti-P-selectin anti-body was ineffective. Here we used genetically altered mice to study the mechanism of PAF in mice. We found that P-selectin-deficient mice are completely protected from the adverse effects of PAF with no mortality or intestinal injury and only mild hemoconcentration and transient hypotension. In contrast, CD18- or intercellular adhesion molecule 1 (ICAM-1)-deficient mice were not protected from PAF-induced tissue injury and death. However, when ICAM-1-, but not CD18-, deficient mice were pretreated with fucoidin, the adverse effects of PAF were markedly reduced; survival was 100%, although hypotension still developed. Neutrophil-depleted mice were protected from PAF-induced intestinal injury but still developed hypotension and hemoconcentration. PAF increases peripheral blood neutrophil counts, probably by inducing granulopoiesis, since neutrophil-depleted mice still showed granulocytosis 60 min after PAF. Thus P-selectin plays an important role in PAF-induced injury in mice, and the selectins and the integrin-ICAM-1 system work in concert to mediate the inflammatory response to PAF in vivo.

Cloning and gene mapping of the chromosome 13q14 region deleted in chronic lymphocytic leukemia

Frequent deletions and loss of heterozygosity in a segment of chromosome 13 (13q14) in cases of B-cell chronic lymphocytic leukemia (CLL) have suggested that this malignancy is caused by inactivation of an unknown tumor suppressor gene located in this region. Toward the identification of the putative CLL tumor suppressor, we have constructed a high-resolution physical map of YAC, PAC, and cosmid contigs covering 600 kb of the 13q14 genomic region. In addition to densely positioned genetic markers and STSs, this map was further annotated by localization of 32 transcribed sequences (ESTs) using a combination of exon trapping, direct cDNA selection, sample sequencing of cosmids and PACs, and homology searches. On the basis of these mapping data, allelic loss analyses at 13q14 using CLL tumor samples allowed narrowing of the genomic segment encompassing the putative CLL gene to <300 kb. Twenty-three ESTs located within this minimally deleted region are candidate exons for the CLL-associated tumor suppressor gene.

[Study of interaction between cytochrome C and cystine using synchronours fluorescence spectroscopy]

The interaction of cytochrome C with cystine as promoter was studied by synchronous fluorescence spectroscopy. After cystine was added into cytochrome C solution, the synchronous flurorescence spectra of tyrosine and tryptophan residues in cytochrome C were monitered with time. The results indicated that the lysine residues in cytochrome C molecules combine with cystine slowly. It induced the small conformational change of cytochrome C molecules.

Insecticidal activity of a recombinant baculovirus containing an antisense c-myc fragment

Attempts to develop baculovirus-based insecticides by insertion of genes encoding enzyme inhibitors, neuropeptides or toxins have met with some success. However, it is often difficult to ensure correct processing or secretion of the encoded peptides. Here we tested a simpler strategy by insertion of an antisense fragment of a host gene to block translation of a protein essential for larval growth and development. We selected the c-myc gene for two main reasons: (i) its protein is known to be well conserved in evolution and to have multiple essential functions during development; and (ii) c-myc family genes have yet to be characterized in insects, thus blockage of essential genes by anti-sense transcripts from a strong virus promoter could provide a sensitive test for the existence of myc-like gene products. An appropriate fragment of the human c-myc gene was inserted downstream from the polyhedrin promoter of Autographa californica nucleopolyhedrovirus and tested in bioassays on Spodoptera frugiperda larvae. Western blot analysis with a human c-myc antibody revealed an endogenous protein band which bound specifically to these antibodies. This band disappeared more rapidly from cells infected with the antisense c-myc recombinant virus than from those infected with c-myc-negative virus. Results of bioassays showed that the antisense construct stopped feeding as soon as the polyhedrin promoter-driven transcripts accumulated, followed shortly by death of the larvae. These results suggest that c-myc-like protein(s) exist in insects and that the antisense strategy is an effective approach to virus insecticide productions.

Isolation, sequencing, and mapping of the human homologue of the yeast transcription factor, SPT5

We isolated the human homologue, SUPT5H, of the yeast transcription factor, SPT5. The human homologue is 1088 aa long compared to 1063 aa for the yeast gene. SUPT5H maps to 19q13, near the ryanodine receptor. Like its family member, SUPT6H, and like yeast SPT5, SUPT5H has a very acidic 5' domain. Like its family member, SUPT6H, but unlike yeast SPT5 or SPT6, SUPT5H has seven MAP kinase sites at its 5' end. In addition, SUPT5H lacks the novel 6-amino-acid repeat (consensus is S-T/A-W-G-G-A/Q) at the C-terminus of yeast SPT5. This argues that while there is functional similarity between SPT5 and SUPT5H, the molecules differ in the signals to which they respond.

Effects of the pharmacokinetic interaction between orally administered sirolimus and cyclosporine on the synergistic prolongation of heart allograft survival in rats

Oral administration, but not continuous intravenous infusion, of sirolimus (SRL) in combination with cyclosporine (CsA) produces a pharmacokinetic interaction, namely increases in the whole blood trough concentrations of SRL ([SRL(WB)]) and CsA ([CsA(WB)]). The effects of this pharmacokinetic interaction on the synergism between SRL and CsA was examined in Wistar Furth (RT1u) recipients of Buffalo (RT1b) heart allografts. A 14-day course of oral SRL produced dose-dependent prolongation of heart allografts: in untreated controls, 0.5 mg/kg SRL per day extended the mean survival time (MST) from 6.4+/-0.5 days to 12.3+/-3.8 days (P<0.05); SRL at 1.0 mg/kg per day prolonged the MST to 18.0+/-5.5 days (P<0.01); at 2.0 mg/kg SRL per day, MST was extended to 52.5+/-13.2 days (P<0.01); and 4.0 mg/kg SRL per day prolonged MST to 90.0+/-41.1 days (P<0.01). Comparison of the in vivo effects after oral versus continuous intravenous SRL administration suggested that the oral bioavailability of SRL is less than 10%. Combinations of oral SRL and CsA synergistically prolonged heart allograft survival, as documented by combination index values of 0.01-0.64 (combination index <1 indicates synergistic interaction). In rats treated with dual drug combinations, CsA increased the bioavailability of SRL by two- to elevenfold, and SRL increased the bioavailability of CsA by two- to threefold, thereby significantly decreasing the oral effective dose (ED) values for each drug. The ED50 for SRL alone is 2.4 mg/kg per day, which produces an average [SRL(WB)] of 13.2 ng/ml. The ED50 for CsA alone is 8.0 mg/kg per day, which produces an average [CsA(WB)] of 1642 ng/ml. However, when the two drugs are combined, the ED50 effect is achieved with only 0.34 mg/kg SRL per day ([SRL(WB)]=1.1 ng/ml) and 2.1 mg/kg CsA per day ([CsA(WB)] =326 ng/ml). Individually, 0.34 mg/kg SRL per day produces an ED9 with an average [SRL(WB)] of 0.6 ng/ml, and 2.1 mg/kg CsA per day produces an ED22 with an average [CsA(WB)] of 174 ng/ml. Thus, the pharmacokinetic interaction between oral SRL and CsA contributes to the in vivo synergism between the two drugs.

Detailed deletion analysis of sporadic breast tumors defines an interstitial region of allelic loss on 17q25

Whole genome analyses of breast tumors with polymorphic markers have detected nonrandom loss of heterozygosity on multiple chromosomes, providing clues to the locations of suspected tumor suppressor genes. Tumors are thought to initiate, progress, and metastasize as mutations accumulate in multiple growth-regulatory genes; thus, identification and characterization of these genes are critical to understanding and controlling breast tumorigenesis. To map more precisely a novel breast tumor suppressor gene that has been localized previously to distal 17q, we constructed a detailed deletion map of 17q25 by analyzing eight microsatellite markers on 39 sporadic primary breast tumors. The smallest overlapping region of interstitial loss was narrowed to approximately 3 cM and included D17S937/AFM107ye3, which showed the highest percentage of allelic loss (41%). These results provide a framework from which a genomic contig will be constructed and candidate transcripts will be analyzed.

A common pathway for p10 and calyx proteins in progressive stages of polyhedron envelope assembly in AcMNPV-infected Spodoptera frugiperda larvae

The assembly of the polyhedron envelope in baculovirus-infected cells has been the subject of several studies, yet it is still poorly understood. We have used immunogold-labelled antibodies to two baculovirus proteins, p10 and calyx (also referred to as polyhedron envelope protein or PEP), to follow envelope assembly in AcMNPV-infected tissues of Spodoptera frugiperda larvae. We show that, in wild type virus, both proteins colocalize in fibrillar structures and associated electron-dense spacers which progress to encircle the polyhedra, as well as in completed polyhedron envelopes. In cells infected with polyhedrin-negative (PH-) viruses, an unusual proliferation of these spacers was observed suggesting a deregulatory event in the envelope assembly process. Results of Northern and Western blot analysis revealed that synthesis of P10 and calyx mRNA and proteins in PH- AcMNPV is unaffected as compared to wild type virus. Taken together, the observed physical and compositional connection between fibrillar structures, spacers and polyhedron envelopes, as well as the abnormal appearance of the spacers in PH- mutants, provide further evidence in support of a cooperative role of these structures in the assembly of the polyhedron envelope.

Endotoxin induces PAF production in the rat ileum: quantitation of tissue PAF by an improved method

PAF (platelet-activating factor) is an endogenous mediator of endotoxin (LPS) shock and intestinal injury. In the present study we used an improved method to quantitate intestinal PAF after LPS injection. Both column and thin layer chromatography (TLC) were used to purify PAF. We found that using C18 column eluted sequentially with 10% acetic acid, ethyl acetate and 70% ethanol, yielded consistent results. TLC yielded falsely high PAF values, possibly from an unknown tissue lipid which co-migrated with PAF, or from toxic ingredients in the silica gel. Moreover, addition of optimal amounts of Tween-20 or ethanol in the bioassay samples enhanced PAF solubility and markedly improved PAF recovery. Lastly, dilution and heparinization of platelet-rich plasma greatly improved the sensitivity of the bioassay. The overall PAF recovery under these optimal conditions was 70-80%. We found that LPS (2-10 mg/kg, iv, 90 min) stimulated PAF production in the rat ileum, but not in the jejunum and colon. The difference in PAF production did not correlate to the numbers of sequestered neutrophils (reflected by myeloperoxidase levels) after LPS injection. This selective PAF production may account for the special vulnerability of the ileum to develop injury during endotoxemia.

Functional contributions of alpha5 subunit to neuronal acetylcholine receptor channels

Ligand-gated ion channels are multi-subunit complexes where each subunit-type is encoded by several related genes. Heterologous expression of any one of the neuronal nicotinic acetylcholine receptors (nAChR) alpha-type subunits, either alone or with any beta-type subunit, typically yields functional nAChR channels. A striking exception is the nAChR alpha5 subunit: although apparently complexed with beta2 and beta4 nAChR subunits in neurons, and expressed in a subset of neurons within the central and peripheral nervous systems, heterologous expression of alpha5, either alone or with any beta-type subunit has failed to yield functional channels. We demonstrate here that alpha5 does participate in nAChRs expressed in hetrologous systems and in primary neurons, and further that alpha5 contributes to the lining of functionally unique nAChR channels, but only if coexpressed with both another alpha- and beta-type subunit. Furthermore, channels containing the alpha5 subunit are potently activated and desensitized by nanomolar concentrations of nicotine.

Beneficial effect of graft perfusion with anti-T cell receptor monoclonal antibodies on survival of small bowel allografts in rat recipients treated with brequinar alone or in combination with cyclosporine and sirolimus

In the present experiments, a multimodality regimen was developed that included an anti-T cell receptor R73 monoclonal antibody and the pharmacologic agents brequinar (BQR), cyclosporine (CsA), and sirolimus (rapamycin; RAPA) to prolong the survival of small bowel (SB) allografts. BQR was the most potent single drug: the 4.0 or 8.0 mg/kg/day BQR doses delivered every second day (q.o.d.) per gavage for 28 days prolonged the survival of Brown Norway (BN; RT1n) SB allografts in Lewis (LEW; RT1l) recipients from a mean survival time of 10.6 +/- 1.9 days in untreated controls to 29.2 +/- 5.8 days, respectively (both P < 0.001). When treatment was extended to 56 days, 8.0 mg/kg/q.o.d BQR produced a mean survival time of 83.8 +/0 33.8 days (P < 0.001), with 2/5 hosts surviving more than 100 days. In a host-versus-graft model, BQR (8.0 mg/kg/q.o.d) delivered for 28 days with CsA (2.0 mg/kg/day) and RAPA (0.04 mg/kg/day) delivered intravenously for 14 days prolonged the survival of BN SB grafts in LEW recipients to 54.4 +/- 21.0 days (P < 0.001). Extending triple-drug therapy to 42 days induced the prolongation of SB allograft survival to greater than 100 days in 5/7 recipients. Although pretransplant perfusion of the grafts with R73 mAb was ineffective alone, the combination of graft perfusion and a 28-day course of BQR (8.0 mg/kg/q.o.d) in the GVH model indefinitely prolonged LEW graft in F1 recipients. Alternatively, indefinite survival of SB allografts ( > 100 days; P < 0.001) was achieved by the combination of a 14-day course of a triple-drug regimen using each agent at subtherapeutic doses, namely BQR (2.0 mg/kg/q.o.d.), CsA (2.0 mg/kg/day), and RAPA (0.04 mg/kg/day). The state of transplantation tolerance is these hosts was documented by the acceptance of donor-type but not third-party heart allografts.

Induction of specific allograft immunity by soluble class I MHC heavy chain protein produced in a baculovirus expression system

Spodoptera frugiperda (Sf9) insect cells secreted a class I MHC RT1.Aa heavy chain protein when infected with baculovirus that bore a construct that contained a honeybee melittin secretion (ms) signal attached to RT1.Aa cDNA. The RT1.Aa heavy chain protein in the culture supernatant and cell lysate immunoprecipitated in the presence of 5 individual anti-RT1.Aa-specific mAb. As was revealed by densitometric analysis, the ms signal increased the production (7- to 17-fold) and secretion (20- to 47-fold) of RT1.Aa protein by Sf9 cells (compared with RT1Aa-Sf9 cells without the ms signal). Subcutaneous immunization with secreted RT1.Aa heavy chain protein of Wistar-Furth (WF; RT1u) rats (day -4) accelerated the rejection of ACI (RT1a), but not third-party Brown Norway (BN; RT1n), heart allografts from 5.9 +/- 0.5 days in controls to 4.0 +/- 0.0 days (P < 0.001); cell lysate from RT1.Aa-Sf9 or ms/RT1.Aa-Sf9 cells reduced ACI heart allograft survival to 3.8 +/- 0.4 days or 3.7 +/- 0.5 days, respectively (P < 0.001). Indirect presentation of RT1.Aa heavy chain proteins by syngeneic macrophages shortened the survival of RT1.Aa-disparate PVG.R8 (RT1.AaDuBuCu) heart allografts in PVG.1U (RT1u) hosts from 6.3 +/- 0.5 days in controls to 4.0 +/- 0.0 days (P < 0.01). Finally, RT1.Aa heavy chain proteins injected into the thymus or into the portal vein (day -14) in combination with anti-T cell receptor mAb (days -14 and -13) induced indefinite survival of ACI liver allografts in Lewis (RT1l) recipients ( > 250 days). Thus, indirect presentation of soluble class I MHC heavy chain proteins (produced in a baculovirus/Sf9 cell system) may either sensitize or induce tolerance in the same fashion as native class I MHC alloantigens expressed on donor tissues.