Human spumaretrovirus antibody reactivity in multiple sclerosis

The role of human spumaretrovirus (HSRV) infections in the pathogenesis of multiple sclerosis (MS) was investigated with recombinant HSRV env-specific enzyme-linked immunosorbent assay. The presence of HSRV antibodies was determined in pairs of serum and cerebrospinal fluid (CSF) samples from 60 MS patients. In 7 of these patients serial serum and CSF samples were obtained in relation to the clinical activity of the disease during a period of 2 years. No increased antibody reactivity was demonstrable in the MS population compared with 14 aseptic meningitis patients, 50 blood donors and 16 healthy controls. Slightly elevated levels of antibodies were demonstrable in serum and/or CSF in 4 MS patients but also in 1 patient with aseptic meningitis, 1 blood donor and 1 child. No marked serum or CSF HSRV antibody fluctuation was observed in the MS patients followed longitudinally. Thus, this study does not support the involvement of HSRV in the pathogenesis of MS.     

Radiology of the continent ileostomy reservoir: I. Method of examination and normal findings

The aim of the present study is to describe the radiologic methods used to study continent ileostomy reservoirs and to depict the normal radiologic features and variations identified by these procedures. During an 8-year period, 408 double-contrast studies were performed in 261 patients. The present study comprises 170 examinations in 99 patients with normal findings. A high-density barium contrast medium and air were used. Modest variation in the size and shape of the reservoirs was observed. The mucosal pattern of the reservoirs resembled that of the ileum but the folds were slightly wider. The continence-providing valves were 3–5 cm long and had a diameter of 2.5–4.0 cm. The diameter of the afferent ileal segments was usually slightly larger than that of more proximal ileal segments, with an upper limit of approximately 4 cm. The efferent ileal segments generally had a straight course without widening or outpouches. Retrograde barium double-contrast examination is a satisfactory method for the evaluation of continent ileostomy reservoirs. Here we define the range of normal variations of such reservoirs as seen on retrograde double-contrast radiologic examinations.     

Stimulation of antigen-specific T- and B-cell memory in local as well as systemic lymphoid tissues following oral immunization with cholera toxin adjuvant.

In the present study we investigated immunological memory at the cellular level following oral immunization using cholera toxin (CT) as the mucosal adjuvant. We found that memory cells, isolated from mice orally primed with keyhole limpet haemocyanin (KLH) admixed with CT adjuvant 8 months earlier, responded by increased proliferation to antigen-challenge in vitro. In contrast, unstimulated memory cells or KLH-stimulated cells from naive mice did not respond. Memory cells were isolated from different lymphoid tissues; spleen (SP), mesenteric lymph nodes (MLN), Peyer's patches (PP) as well as the intestinal lamina propria (LP). Thus, oral immunization using CT adjuvant promoted the generation of memory cells that were present in both systemic and local intestinal lymphoid tissues. The demonstration of lymphokine production in the KLH-responsive cultures indicated the presence of antigen-specific memory T cells. Lymphokine production early in culture was dominated by interleukin-2 (IL-2), which peaked on day 2-3, followed by IL-5 and, in particular, interferon-gamma (IFN-gamma) which increased over time. Lamina propria memory cells were found to proliferate poorly to recall antigen in vitro compared to lymphocytes from SP or MLN. In contrast, very significant production of IL-5 and, in particular, IFN-gamma was demonstrable in LP cell cultures. The use of CT adjuvant also stimulated the generation of antigen-specific memory B cells following oral immunization. This was evidenced by KLH-specific antibody production in antigen-challenged memory lymphocyte cultures. The memory B cells produced IgM anti-KLH, while no detectable antigen-specific IgG or IgA was found. Unstimulated memory cells or naive cells failed to produce anti-KLH antibodies. These in vitro findings provide evidence that oral immunization using CT adjuvant stimulates both antigen-specific memory T and B cells. Furthermore, our data suggest the existence of memory B cells following oral CT adjuvant immunization which have retained the ability to produce IgM and which therefore probably have not undergone terminal isotype switch differentiation to other isotypes and thus have not deleted the mu constant heavy-chain gene. Finally, our data also suggest that memory T and B cells, either sessile in the various lymphoid tissues or recirculating, can be activated by antigen in situ in, for example, lymph nodes and spleen and, more importantly, in the intestinal LP itself.     

Oral administration of a streptococcal antigen coupled to cholera toxin B subunit evokes strong antibody responses in salivary glands and extramucosal tissues.

Generation of local and systemic immune responses by the oral administration of antigens is frequently inefficient, requiring large quantities of immunogens and yielding only modest antibody responses. In this study, we have demonstrated that oral administration of microgram amounts of Streptococcus mutans protein antigen I/II covalently coupled to the B subunit of cholera toxin elicits vigorous mucosal as well as extramucosal immunoglobulin A and G antistreptococcal antibody responses in mice. These responses were manifested by the presence of large numbers of antibody-secreting cells in salivary glands, mesenteric lymph nodes, and spleens and by the development of high levels of circulating antibodies. This novel immunization strategy may find broad application in the construction of oral vaccines for the control of infectious diseases caused by pathogens encountered at mucosal and extramucosal sites.     

Cholera toxin adjuvant greatly promotes antigen priming of T cells

Cholera toxin (CT) given perorally is a powerful mucosal immunogen and adjuvant. Information that explains the adjuvant effect of CT may be used for the development of more effective oral vaccines and might also contribute to our understanding of the mechanisms involved in regulating mucosal immunity. The present study was undertaken to investigate if CT administered together with keyhole limpet hemocyanin (KLH) would act to promote or inhibit priming of KLH-specific T cells and whether the adjuvant effect of CT is restricted to mucosal immune responses or is a generalized phenomenon due to direct immunomodulating effects of CT. We found that CT adjuvant greatly augmented the effectiveness of a single oral priming immunization with KLH: re-challenge with KLH in vitro 1 week following immunization gave several-fold stronger proliferation in KLH-specific spleen, mesenteric lymph node, Peyer's patch and gut lamina propria T cells from KLH + CT adjuvant as opposed to KLH only-treated mice. Moreover, several-fold stronger cytokine production, i.e. interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10 and interferon-Y accompanied the enhanced proliferative response of T cells from CT adjuvant-treated mice. The adjuvant effect of CT was not restricted to mucosal immune responses but was evident also following a single parenteral immunization with KLH + CT. Limiting dilution analysis revealed that CT adjuvant promoted a 20- to 40-fold increase in the frequency of primed KLH-specific T cells. Phenotypic and functional analyses clearly demonstrated that CT adjuvant primarily enhanced priming of CD4⁺ rather than CD8⁺ T cells and the pattern of lymphokine secretion disclosed that CT most probably promoted antigen priming of both T_hl and T_h2 type of CD4⁺ T precursor cells.     

Interferon-gamma receptor-deficient mice exhibit impaired gut mucosal immune responses but intact oral tolerance.

Interferon-gamma (IFN-gamma) receptor knock-out (IFN-gamma R -/-) mice were used to analyse the role of IFN-gamma in mucosal immune responses following oral immunization. We found that the IFN-gamma R -/- mice demonstrated 50% reduced spot-forming cell (SFC) responses in the gut lamina propria and spleen after oral immunization with keyhold limpet haemocyanin (KLH) plus cholera toxin (CT) adjuvant. The IFN-gamma R -/- mice exhibited 10-fold reduced total serum KLH-specific antibody levels compared with wild-type mice after oral immunization, while after intravenous immunization, no such difference was seen, suggesting a selective impairment of mucosal immune responses. Moreover, oral immunizations resulted in impaired interleukin-4 (IL-4), IL-10 and IFN-gamma production by spleen T cells from IFN-gamma R -/- mice, indicating that no reciprocal up-regulation of Th2-activities had occurred despite the lack of IFN-gamma R function. No reduction in Th1 or Th2 cytokines was observed following systemic immunizations. Despite potentially strong modulating effects of IFN-gamma on epithelial cell IgA transcytosis and electrolyte barrier functions, CT-immunized IFN-gamma R -/- mice demonstrated unaltered protection against CT in ligated intestinal loops together with normal anti-CT IgA and total IgA levels in gut lavage. Oral feeding with KLH followed by parenteral immunization resulted in strongly suppressed SFC numbers and reduced cell-mediated immunity in both wild-type and IFN-gamma R -/- mice. CT-adjuvant abrogated induction of oral tolerance in both IFN-gamma R -/- and wild-type mice. Collectively, our data argue that the two major response patterns induced by oral administration of protein antigen, i.e. active IgA immunity and oral tolerance, are differently regulated. Thus, IFN-gamma R -/- mice have impaired mucosal immune responses while induction of oral tolerance appears to be unaffected by the lack of IFN-gamma functions.     

Acyclovir treatment of relapsing-remitting multiple sclerosis

Acyclovir treatment was used in a randomized, double-blind, placebo-controlled clinical trial with parallel groups to test the hypothesis that herpes virus infections are involved in the pathogenesis of multiple sclerosis (MS). Sixty patients with the relapsing-remitting form of MS were randomized to either oral treatment with 800 mg acyclovir or placebo tablets three times daily for 2 years. The clinical effect was investigated by an extensive test battery consisting of neurological examinations, neuro-ophthalmological and neuropsychological tests, and evoked potentials. Results were based on intent-to-treat data and the primary outcome measure was the exacerbation rate. In the acyclovir group (n = 30), 62 exacerbations were recorded during the treatment period, yielding an annual exacerbation rate of 1.03. The placebo group (n = 30) had 94 exacerbations and an annual exacerbation rate of 1.57. Thus, 34% fewer exacerbations were encountered during acyclovir treatment. This difference in exacerbation rate between the treatment groups was not significant (P = 0.083). However, this trend to a lower disease activity in acyclovir-treated patients was supported in subsequent data analysis. If the patients were grouped according to exacerbation frequencies, i.e. into low (0–2), medium (3–5) and high (6–8) rate groups, the difference between acyclovir and placebo treatment was significant (P = 0.017). Moreover, in a subgroup of the population with a duration of the disease of at least 2 years providing an exacerbation rate base-line before entry, individual differences in exacerbation rates were compared between the 2-year pre-study period and the study period in acyclovir-treated (n = 19) and placebo (n = 20) patients and acyclovir-treated patients showed a significant reduction of exacerbations (P = 0.024). Otherwise, neurological parameters were essentially unaffected by acyclovir treatment and there were no convincing signs of reduced neurological deterioration in the acyclovir group. This study indicates that acyclovir treatment might inhibit the triggering of MS exacerbations and thus suggests that acyclovir-susceptible viruses might be involved in the pathogenesis of MS. This possibility warrants further investigation.