Effect of neonatal or later capsaicin treatment on bronchial reactivity in sensitized rats. Relation to humoral changes

Treatment of ovalbumin-sensitized rats with capsaicin resulted in altered bronchial reactivity to both ovalbumin and serotonin. The increase in bronchial reactivity to ovalbumin in neonatally capsaicin-treated rats compared to animals only sensitized may be influenced by the changed ratios of IgA, IgE, and IgG antibodies, together with the inflammation in the lung. Thus, capsaicin given neonatally inhibited the formation of antibodies, both specific titers and total levels, in bronchial lavage.     

Functional microtubules are required for antigen processing by macrophages and dendritic cells

Antigen-presenting cells readily phagocytose antigens and channel them through various membrane-bound organelles within the cell. In previous studies, we demonstrated that macrophages concentrated and localized particulate antigens to the trans-Golgi prior to displaying the MHC-class I-antigenic peptides on the cell surface. In this study, we evaluated the importance of cytoskeletal elements in the intracellular trafficking of soluble and liposome-encapsulated ovalbumin in murine bone marrow-derived macrophages and human dendritic cells. F-actin, as identified by staining with fluorescein phalloidin, was observed at the point of contact between soluble or liposomal antigen and the cell membrane, suggesting that a rearrangement of the cytoskeleton occurs to facilitate the uptake of the antigens. Cells were incubated with colchicine, a microtubule depolymerizing agent, or paclitaxel, a microtubule polymerizing agent, before the addition of Texas Red-labeled ovalbumin or liposome-encapsulated Texas Red-labeled ovalbumin. Colchicine disrupted the trans-Golgi, whereas the trans-Golgi complexes were intact in paclitaxel treated cells. In either paclitaxel or colchicine-treated macrophages, internalized liposomal ovalbumin was not concentrated in the area of the trans-Golgi as determined by staining with fluorescent ceramide. In contrast, soluble ovalbumin was concentrated in the region of the trans-Golgi in 15% of the dendritic cells treated with paclitaxel, whereas 6% of the dendritic cells were able to concentrate liposomal antigen. In colchicine-treated dendritic cells, both soluble and liposomal antigens were internalized but did not localize to the area of the trans-Golgi. These data suggest that trafficking of soluble and liposome-encapsulated ovalbumin requires a functional microtubule-dependent translocation system.     

Transcutaneous immunization with bacterial ADP-ribosylating exotoxins, subunits, and unrelated adjuvants

We have recently described a needle-free method of vaccination, transcutaneous immunization, consisting of the topical application of vaccine antigens to intact skin. While most proteins themselves are poor immunogens on the skin, we have shown that the addition of cholera toxin (CT), a mucosal adjuvant, results in cellular and humoral immune responses to the adjuvant and coadministered antigens. The present study explores the breadth of adjuvants that have activity on the skin, using diphtheria toxoid (DTx) and tetanus toxoid as model antigens. Heat-labile enterotoxin (LT) displayed adjuvant properties similar to those of CT when used on the skin and induced protective immune responses against tetanus toxin challenge when applied topically at doses as low as 1 microg. Interestingly, enterotoxin derivatives LTR192G, LTK63, and LTR72 and the recombinant CT B subunit also exhibited adjuvant properties on the skin. Consistent with the latter finding, non-ADP-ribosylating exotoxins, including an oligonucleotide DNA sequence, as well as several cytokines (interleukin-1beta [IL-1beta] fragment, IL-2, IL-12, and tumor necrosis factor alpha) and lipopolysaccharide also elicited detectable anti-DTx immunoglobulin G titers in the immunized mice. These results indicate that enhancement of the immune response to topical immunization is not restricted to CT or the ADP-ribosylating exotoxins as adjuvants. This study also reinforces earlier findings that addition of an adjuvant is important for the induction of robust immune responses to vaccine antigens delivered by topical application.     

Enhancement by lipid A of mucosal immunogenicity of liposome-associated cholera toxin

Two methods that might enhance the mucosal immunogenicity of a protein antigen, cholera toxin (CT), were studied in rats: association of CT with liposomes, and coadministration of CT with lipid A. Enteric priming by CT was not enhanced when the antigen was trapped within liposomes or bound to their surface via GM1 ganglioside, nor was it improved when CT was mixed with lipid A or with liposomes containing lipid A. However, lipid A did enhance priming by liposome-associated CT when the lipid A was incorporated into CT-bearing liposomes. It is concluded that lipid A can act as an adjuvant for a local IgA response to a mucosally applied antigen, at least when lipid A and the antigen are associated on a liposome carrier.     

Studies on a strain of chloroquine-resistant Plasmodium falciparum from Thailand

Infections with a strain of Plasmodium falciparum from Thailand, termed the Thailand (JHK) strain, were established in 25 non-immune volunteers in a non-endemic area under conditions precluding reinfection. Eleven volunteers received chloroquine in usually curative doses on a three-day schedule during acute clinical malaria attacks. Volunteers also received (again during acute clinical attacks) hydroxychloroquine, amodiaquine, mepacrine, pyrimethamine, proguanil or 377-C-54, alone or in combination. These regimens failed, both before and after passage of the strain through mosquitos, to effect radical cure of the infection. Radical cure was achieved by administration of 1350 mg or 1620 mg of quinine base daily for seven days.     

Choleragen-mediated release of trapped glucose from liposomes containing ganglioside GM1.

125I-Labeled choleragen was bound to liposomes containing galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylglucosylceramide (GM1), but not in large amounts to ganglioside-free liposomes nor to those containing N-acetylneuraminylgalactosylglucosylceramide (GM3), N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylglucosylceramide (GM2), or N-acetylneuraminylgalactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylglucosylceramide (GD1a). Choleragen released trapped glucose only from GM1-liposomes. This choleragen-induced glucose release from GM1-liposomes was relatively rapid for the first few minutes, then continued more slowly. The amount of glucose released from liposomes in 30 min was dependent on both the GM1 content and choleragen concentration. Prior incubation of GM1-liposomes with anti-GM1 antiserum prevented the choleragen-dependent release of trapped glucose. After incubation of GM1-liposomes with choleragen, addition of anticholeragen antibodies and complement led to more extensive glucose release. Under these latter conditions a much smaller glucose release was observed also from liposomes containing GM1 or N-acetylneuraminylgalactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylglucosylceramide in the absence of choleragen. These releases were attributed to naturally-occurring antiganglioside antibodies in the antiserum and complement. Ganglioside-free liposomes did not release glucose in response to anticholeragen and complement. It appears that choleragen in the absence of other proteins binds specifically to liposomes containing GM1 and can induce permeability changes.