Lipid based particulate formulations for the delivery of antigen

Particulate adjuvant systems are largely classified according to their functional characteristics, such as the nature of the typical immune response they induce, or their perceived mode of action. From a formulation science perspective, it is practical to classify antigen delivery systems according to the physical nature of the formulations. This article discusses lipid based particulate systems, grouped according to the nature of their predominant lipid constituent.

Quil A-lipid powder formulations releasing ISCOMs and related colloidal stuctures upon hydration

The aim of the present study was to prepare solid Quil A-cholesterol-phospholid formulations (as powder mixtures or compressed to pellets) by physical mixing or by freeze-drying of aqueous dispersions of these components in ratios that allow spontaneous formation of ISCOMs and other colloidal stuctures upon hydration. The effect of addition of excess cholesterol to the lipid mixtures on the release of a model antigen (PE-FITC-OVA) from the pellets was also investigated. Physical properties were evaluated by X-ray powder diffractometry (XPRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and polarized light microscopy (PLM). Characterization of aqueous colloidal dispersions was performed by negative staining transmission electron microscopy (TEM). Physically mixed powders (with or without PE-FITC-OVA) and pellets prepared from the same powders did not spontaneously form ISCOM matrices and related colloidal structures such as worm-like micelles, ring-like micelles, lipidic/layered structures and lamellae (hexagonal array of ring-like micelles) upon hydration as expected from the pseudo-temary diagram for aqueous mixtures of Quil A, cholesterol and phospholipid. In contrast, spontaneous formation of the expected colloids was demonstrated for the freeze-dried lipid mixtures. Pellets prepared by compression of freeze-dried powders released PE-FITC-OVA slower than those prepared from physically mixed powders. TEM investigations revealed that the antigen was released in the form of colloidal particles (ISCOMs) from pellets prepared by compression of freeze-dried powders. The addition of excess cholesterol slowed down the release of antigen. The findings obtained in this study are important for the formulation of solid Quil A-containing lipid articles as controlled particulate adjuvant containing antigen delivery systems. (c) 2004 Elsevier B.V. All rights reserved.

Children’s respiratory health and daily particulate levels in ten non-urban communities

We conducted a study to assess the association between the acute respiratory health of children and the levels of particulates in communities near and away from active opencast coal mines. The study enrolled children aged 1–11 years from the general population of five socioeconomically matched pairs of nonurban communities in northern England. Diaries of respiratory events were collected for 1405 children, and information was collected on the consultations of 2442 children with family/general practitioners over the 6-week study periods during 1996–1997, with concurrent monitoring of particulate levels. The associations found between daily PM10 levels and respiratory symptoms were frequently small and positive and sometimes varied between communities. The magnitude of these associations were in line with those from previous studies, even though daily particulate levels were low, and the children were drawn from the general population, rather than from the population with respiratory problems. The associations among asthma reliever use, consultations with general practitioners, and daily particulate levels were of a similar strength but estimated less precisely. The strength of association between all respiratory health measures and particulate levels was similar in communities near and away from opencast coal mining sites.

HPV6b virus like particles are potent immunogens without adjuvant in man

Subjects with genital warts were immunized three times or more with HPV6b VLPs without adjuvant. All immunized subjects had DTH to HPV6b L1 protein. Of 32 subjects, nine had HPV6b specific antibody prior to immunization and 22 acquired antibody with immunization. VLP specific antibody increased following a single immunization in 6 of 8 subjects with low level antibody at recruitment. Complete regression of genital warts was observed in 25 of 33 evaluable subjects over the 20-week observation period. We conclude that immunization with HPV6b L1 VLPs without adjuvant induces immunity to the L1 protein epitopes recognised during natural infection, and may accelerate regression of warts. (C) 2000 Elsevier Science Ltd. All rights reserved.

Induction of an antigen-specific CTL response by a conformationally biased agonist of human C5a anaphylatoxin as a molecular adjuvant

A conformationally biased decapeptide agonist of human C5a anaphylatoxin (YSPKPMPLaR) was used as a molecular adjuvant in stimulating an Ag-specific CTL response against murine P815S target cells expressing an Ld-restricted CTL epitope of the hepatitis B surface Ag (HBsAg), Groups of BALB/c mice (H-2(d)) were immunized with aqueous solutions of the HBsAg CTL epitopes (IPQSLDSWWTSL and IPQSLDSTaVTSLRR); the C5a agonist (YSFKPMPLaR); the C5a agonist and HBsAg CTL epitopes admired (IPQSLDSWWTSL and IPQSLDSWWTSLRR + YSFKPMPLaR); the C5a-active, HBsAg CTL epitope-C5a agonist constructs (IPQSLDSWWTSLYSFKPMPLaR, IPQSLDSWWTSLRRYSFKPMPLaR, and IPQSLDSWWTSLRVRRYSFPMPLaR); a C5a-inactive, reverse-moiety construct (YSFKPMPLaRRRIPQSLDSWWTSL); and a C5a-attenuated, carboxyl-terminal-blocked construct (IPQSLDSWWTSLRRYSFKPMPLaRG). Ag-specific CD8(+) CTL responses were observed after the secondary boost in the absence of any added adjuvant only in mice that were immunized with C5a-active contructs, IPQSLDSWWTSLRRYSFKPMPLaR and IPQSLDSWWTSLRVRRYSFKPMPLaR. These two C5a-active immunogens contained potential subtilisin-sensitive linker sequences between the HBsAg CTL epitope and the C5a agonist; i.e., a double-Arg (RR) and a furin protease sensitive sequence (RVRR), The introduction of these potentially cleavable sequences may be a method of increasing the likelihood of liberating the CTL epitope from the C5a agonist by intracellular proteases, thereby facilitating entry of the epitope into Ag-processing pathways via an exogenous route.

Methods for effective fluidization of particulate food materials

Depending on the size and shape of the materials, methods employed to achieve effective fluidization during fluid bed drying varies from use of simple hole distributors for small, light weight materials to special techniques for lager and/or moist materials. This paper reviews common air distributors used in fluidized bed drying of food particulates. Also it reviews special methods of fluidizing larger irregular food particulates.

Gene-engineered T cells as a superior adjuvant therapy for metastatic cancer

The major limiting factor in the successful application of adjuvant therapy for metastatic disease is the lack of adjuvant specificity that leads to severe side effects. Reasoning that T cells of the immune system are highly specific, we generated tumor-specific T cells by genetic modification of mouse primary T cells with a chimeric receptor reactive with the human breast cancer-associated Ag erbB-2. These T cells killed breast cancer cells and secreted IFN-gamma in an Ag-specific manner in vitro. We investigated their use against metastatic breast cancer in mice in an adjuvant setting, and compared their effectiveness with the commonly applied adjuvants doxorubicin, 5-fluorouracil, and herceptin. Mice were inoculated orthotopically with the human erbB-2-expressing spontaneously metastatic mouse breast cancer 4T1.2 in mammary tissue, and the primary tumor was surgically removed 8 days later., Significant metastatic disease was demonstrated in lung and liver at the time of surgery on day 8 with increased tumor burden at later time points. T cell adjuvant treatment of day 8 metastatic disease resulted in dramatic increases in survival of mice, and this survival was significantly greater than that afforded by either doxorubicin, 5-fluorouracil, or herceptin.

Molecular adjuvant effects of a conformationally biased agonist elf human C5a anaphylatoxin

A conformationally biased decapeptide agonist of human C5a anaphylatoxin (YSFKPMPLaR) was used as a molecular adjuvant in stimulating Ab responses against peptide epitopes derived from human MUC1 glycoprotein and the human mu and kappa opioid receptors. C57BL6 mice were immunized with the MUC1 epitope (YKQGGFLGL); the C5a agonist (YSFKPMPLaR); YSFKPMPLaR and YKQGGFLGL together, but unconjugated; a C5a-active, MUC1 epitope construct (YKQGGFLGLYSFKPMPLaR); and a C5a-inactive, reversed moiety construct (YSFKPMPLaRYKQGGFLGL). High Ab titers specific for the MUC1 epitope were observed Only in mice immunized with the C5a-active epitope construct. Similar results were obtained in BALB/c mice immunized with the C5a-active, MUC1 epitope construct, Abs from the sera of the C57BL6 mice were predominately of the IgG2a, IgC2b, and IgM isotypes and were reactive against human recombinant MUC1 and MUC1 expressed by the Panc-1 M1F.15 pancreatic cell line, When compared with the corresponding KLH-epitope conjugates in C57BL6 mice, the epitope-C5a agonist constructs produced titers of specific IgG Abs of isotypes distinct from those generated by the keyhole limpet hemocyanin-epitope conjugates, Rabbits immunized with a mu opioid receptor epitope-C5a agonist construct (GDLSDPCGNRTNLGGRDSLYSFKPMPLaR) or a kappa opioid receptor epitope-C5a agonist construct (FPGWAEPDSNGSEDAQLYSFKPMPLaR) generated high titer, epitope-specific Ab responses, Ab titers generated in response to the opioid epitope-C5a agonist constructs were comparable to those generated by the opioid KLH-epitope conjugates, The results of this study are discussed in terms of possible mechanisms by which the conformationally biased C5a agonist serves as a molecular adjuvant.

A lipophilic adjuvant carrier system for antigenic peptides

A lipoamino acid based synthetic peptide, (Lipid Core Peptide, LCP) derived from the conserved region of group A streptococci (GAS) was evaluated as potential candidate in a vaccine to prevent GAS-associated diseases, including rheumatic heart disease and post-streptococcal acute glomerulonephritis. Multiple copies of a peptide sequence from the bacterial surface M protein were incorporated into a lipid core and it was used to immunize mice with and without the application of adjuvant. The LCP construct had significantly enhanced immunogenicity compared with the monomeric peptide epitope. Furthermore, the peptides incorporated into the LCP system generated antibodies without the use of any conventional adjuvant.

Lipoamino acid-based adjuvant carrier system: Enhanced immunogenicity of group a streptococcal peptide epitopes

Lipoamino acid-based synthetic peptides (lipid core peptides, LCP) derived from the type-specific and conserved region determinants of group A streptococci (GAS) were evaluated as potential candidate sequences in a vaccine to prevent GAS-associated diseases, including rheumatic heart, disease and poststreptococcal acute glomerulonephritis. The LCP peptides had significantly enhanced immunogenicity as compared with the monomeric peptide epitopes. Furthermore, the peptides incorporated into the LCP system generated epitope-specific antibodies without the use of any conventional adjuvant.