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N Lycke

Publications and source records attributed to N Lycke.

81 records · Page 5Linked to original sources
PubMed1986

Strong biotype and serotype cross-protective antibacterial and antitoxic immunity in rabbits after cholera infection.

We studied whether immunity evoked by infection with classical or El Tor V. cholerae 01 organisms in rabbits (the RITARD model) also gives protection against cholera caused by V. cholerae of heterologous biotype as well as serotype, and whether such protection is antibacterial and/or antitoxic. A primary infection with a classical Ogawa or El Tor Inaba strain resulted in intestinal colonization and diarrheal disease in a dose-related manner though the El Tor strain was more virulent. As few as 10(3) El Tor organisms gave disease in more than 90% of the rabbits as compared to 10(9) classical organisms (ED90); the El Tor strain also gave rise to diarrhea with earlier onset and of greater severity and longer duration. The primary infection induced strong protective immunity against later challenge with either the homologous or the heterologous strain in doses that corresponded to 1,000 x ED90. Protection was associated with marked inhibition of colonization, and when rabbits convalescing from cholera infection were challenged with graded doses of bacteria or purified toxin in ligated intestinal loops significant antibacterial as well as antitoxic immunity was evident. Titer rises in serum vibriocidal and anti-lipopolysaccharide antibodies were similar after infection with either strain, whilst antitoxin titer rises were more marked after El Tor infection. During infection V. cholerae 01 organisms seem to express protective antigens that stimulate immunity which extends across both biotype and serotype barriers.

Animals↗
PubMed1986

Intestinal mucosal memory and presence of memory cells in lamina propria and Peyer's patches in mice 2 years after oral immunization with cholera toxin.

The build-up of long-term immunological memory in the gut mucosal immune system may explain long-lasting protection against new attacks of cholera in convalescents from natural disease. We have looked for gut mucosal antitoxin immunological memory and memory cells in mice after oral immunization with cholera toxin. Our results show that mice that were orally primed with cholera toxin and then boosted 2 years later with a single oral antigen dose mounted a rapid and vigorous IgA antitoxin response in the intestinal lamina propria. A specific secondary antitoxin response could also be elicited without any in-vivo boosting by in-vitro stimulation of isolated lymphocytes from the lamina propria, Peyer's patches, mesenteric lymph nodes, and spleen. The results provide evidence for the almost life-long persistence of anti-cholera toxin memory B cells (and perhaps also T cells) in the intestine and probably also recirculating cells, after oral immunization with cholera toxin. A functional antitoxic immune response may be boosted rapidly on renewed enteral exposure to cholera toxin by the stimulation of memory cells both in the lamina propria and in the Peyer's patches.

Administration, Oral↗
PubMed1986

A sensitive method for the detection of specific antibody production in different isotypes from single lamina propria plasma cells.

A sensitive and reproducible method for the detection of specific antibody production (or total immunoglobulin secretion) at the single cell level from isolated lamina propria lymphocytes was developed. The cells were prepared from mouse intestinal mucosa by enzyme extraction with collagenase, and antibody secretion was demonstrated with a solid phase enzyme-linked immunospot (ELISPOT) assay. Oral immunizations with cholera toxin or keyhole limpet haemocyanin to mice gave high numbers of highly antigen-specific spot-forming cells (SFC) among isolated lamina propria lymphocytes. Spots were shown to result from active synthesis of immunoglobulin in vitro. The variation in SFC numbers between individual animals after a given protocol of oral immunizations was found to be 25% and between equal groups analysed on different occasions, 12%. Kinetics of primary as well as secondary immune responses after oral immunizations with cholera toxin were easily monitored. A single dose of cholera toxin gave rise to 230 antitoxin SFC/10(7) isolated lamina propria lymphocytes. Each additional dose stimulated to increasing numbers of specific SFC with roughly 7000 antitoxin SFC/10(7) cells after five immunizations. Monitoring of day-by-day responses after oral booster immunizations demonstrated peak SFC numbers on day 8 after antigen administration. The total number of immunoglobulin-secreting (Ig) cells and the isotype distribution of specific SFC could also be determined. In the peak antitoxin response, 8% of the isolated total Ig-secreting lamina propria cells were active against cholera toxin, and of these 80% were producing IgA. This method has also been successfully used in humans and rabbits to demonstrate specific antibody production by single lamina propria plasma cells.

Animals↗
PubMed1986

Strong adjuvant properties of cholera toxin on gut mucosal immune responses to orally presented antigens.

There is a great need for substances that can act as adjuvants on local mucosal immune responses to perorally (p.o.) administered immunogens and which could be included in future oral vaccines. In this study we show that in mice cholera toxin (CT) is a potent adjuvant on enteric mucosal immune responses to related (cholera B subunit) as well as unrelated (KLH) antigens presented by the p.o. route. The adjuvant action of CT was dose-dependent and was achieved only when CT was given p.o. and together with the antigen. Both priming (memory induction) and boosting of the gut mucosal immune system by the oral route were greatly potentiated by CT. High numbers of specific antibody-producing cells as well as substantial mucosal memory in the lamina propria were stimulated by p.o. priming immunizations if CT adjuvant was included. Anamnestic responses could be elicited by a single p.o. booster immunization for at least 10 weeks and probably much longer. The adjuvant action of CT is suggested to involve activation of adenylate cyclase and cyclic AMP-mediated signals with differential effects on B and regulatory T intestinal lymphocytes. The adjuvant-active dose of CT, 100-500 ng, was lower than the immunogenic dose (2 micrograms) and much below the p.o. dose needed for detectable net fluid secretion in mouse intestine (5-10 micrograms). Cholera B subunit (10 micrograms) administered p.o. together with 500 ng of CT was 50 times more effective in stimulating gut mucosal anti-toxin responses compared with B subunit vaccine alone. Our results suggest that CT or substances that use similar adjuvant mechanisms may substantially increase the mucosal immunogenicity and efficacy of non-replicating oral vaccines.

Adenylyl Cyclases↗
PubMed1985

Cholera antibody production in vitro by peripheral blood lymphocytes following oral immunization of humans and mice.

We have studied specific antibody production from peripheral blood lymphocytes (PBL) after oral cholera immunization of humans and mice. Two oral immunizations with cholera toxin (CT) in mice or a single dose of the combined cholera B-subunit/whole cell vaccine in humans gave rise to PBL which spontaneously secreted cholera-specific antibodies when cultured in vitro. A high proportion of IgA antibodies was seen in contrast to antibodies produced by PBL after parenteral immunization which were predominantly IgG. Cultured PBL produced antitoxin as well as anti-lipopolysaccharide antibodies after oral immunization, whereas serum only revealed titre rises for anti-CT. Antibody-secreting PBL appeared in the blood 2-4 days after immunization and persisted for about two weeks with a peak after 6-8 days. Mitogen stimulation in vitro of PBL from multiply-orally vaccinated humans activated a population of specific IgM antibody-secreting cells which persisted for several months following immunization, suggesting the presence of long-lived memory cells. The analysis of IgA antibody production from in-vitro cultured PBL seems to be a promising technique to assess the local immunogenicity of oral vaccines.

Adult↗
PubMed1983

Monoclonal antibodies to cholera toxin with special reference to cross-reactions with Escherichia coli heat-labile enterotoxin.

Seventy monoclonal antibodies to cholera toxin were prepared and characterized. All were of immunoglobulin G (IgG) isotypes (39 IgG1, 29 IgG2, and 2 IgG3). A total of 61 clones produced antibody directed against the B subunit, and 9 clones produced antibodies with specificity for the cholera toxin A subunit. Among both the anti-B and anti-A antibodies, there were representatives which showed full cross-reactivity with the heat-labile enterotoxin of Escherichia coli (14 clones), others which gave partial cross-reactions (12), and still others (44) which did not cross-react. Although 24 of 25 tested anti-B monoclonal antibodies could neutralize cholera toxin, none of the 9 anti-A clones had any detectable neutralizing ability. Among the anti-B antibodies, those which cross-reacted completely with E. coli heat-labile enterotoxin all had strong cholera toxin-neutralizing capacity, whereas those with lesser or no degree of cross-reactivity varied more in their neutralizing potency. The isolation of monoclonal antibodies that distinguish between enterotoxins of different bacterial origin suggests the possibility of developing immunodiagnostic methods allowing species-specific enterotoxin detection in stools of patients with diarrheal disease.

Antibodies, Monoclonal↗
PubMed1983

IgA isotype restriction in the mucosal but not in the extramucosal immune response after oral immunizations with cholera toxin or cholera B subunit.

Intestinal mucosal as well as extramucosal antibody responses were studied in mice after peroral immunizations with cholera toxin or cholera B subunit. The immunizations with cholera toxin gave rise to a marked response with antitoxin-secreting cells (PFC) in Peyer's patches (PP), mesenteric lymph nodes (MLN) and spleen showing isotype distribution of IgG greater than IgA greater than IgM and with PFC kinetics in MLN and spleen that suggested migration of cells from PP after peroral administration rather than cells stimulated in situ by adsorbed antigen. Highest numbers of PFC were obtained after 2 immunizations, and further administrations resulted in a decrease in the PFC response in MLN and spleen, while the PP responsiveness was relatively unchanged, and interestingly, protective immunity and IgA-dominated antitoxin titers in intestinal washings increased markedly by the additional boosters. Animals immunized with cholera B subunit, which lacks the adenylate cyclase-stimulating capacity of cholera toxin, showed similar PFC responses in extramucosal organs as those receiving cholera toxin but were poorly protected and had correspondingly lower IgA antitoxin titers in intestinal washings. These results suggest that the mucosal IgA antitoxin predominance is mainly due to regulatory mechanisms operating on the end-stage differentiation of the committed B cells in lamina propria and that this differentiation, as judged from the different results with cholera toxin and its B subunit, might be influenced by cyclic AMP.

Animals↗
PubMedDate not supplied

Accelerated acute rejection of the intestinal graft in CD28-deficient mice.

OBJECTIVE: Multiple in vivo studies have shown that the pace and severity of graft rejection is little or not at all changed by deleting CD28 molecules in the recipient. These findings contrast with the effects of monoclonal antibody therapy aimed the same costimulatory target. The objective of the present study was to evaluate how the acute rejection process is affected in CD28-deficient mice using a fully allogeneic, highly immunologically reactive transplant model. METHODS: Heterotopic vascularized small bowel transplants were performed in 24 recipient mice divided into 4 groups: 2 wild-type and 2 knockout groups. Each group consisted of 5 to 7 animals in which BalbC mice were used as intestinal donors to either wild-type C57BL6 or C57BL6 background CD28-deficient recipient mice. Selected endpoints were 3 and 6 postoperative days (POD). Intestinal rejection was evaluated by mucosal laser Doppler flowmetry (expressed in perfusion units) and histology (expressed in rejection grades). RESULTS: Acute rejection occurred in both wild-type and CD28-deficient groups. At POD 3, no significant difference was noted between groups in terms of mucosal perfusion and histology. At POD 6, significant differences in graft mucosal perfusion and histology revealed a more aggressive rejection in the CD28-deficient group compared to the wild-type group. CONCLUSIONS: The present study showed that the severity of intestinal graft rejection responses was amplified by deleting CD28 molecules. Together with data from other studies, these results suggest a different pattern of distribution and/or activation of CD28/B7 receptors in various organs.

Acute Disease↗