Chlamydia pneumoniae and Chlamydia Trachomatis Infection Differentially Modulates Human Dendritic Cell Line (MUTZ) Differentiation and Activation.

Chlamydia trachomatis and Chlamydia pneumoniae are important human pathogens that infect the urogenital/anorectal and respiratory tracts, respectively. Whilst the ability of these bacteria to infect epithelia is well defined, there is also considerable evidence of infection of leucocytes, including dendritic cells (DCs). Using a human dendritic cell line (MUTZ), we demonstrate that the infection and replication of chlamydiae inside DCs is species and serovar specific and that live infection with C. pneumoniae is required to upregulate costimulatory markers CD80, CD83 and human leucocyte antigen (HLA)-DR on MUTZ cells, as well as induce secretion of interleukin (IL)-2, IL-6, IL-8, IL-12 (p70), interferon-gamma and tumour necrosis factor-alpha Conversely, C. trachomatis serovar D failed to upregulate DC costimulatory markers, but did induce secretion of high concentrations of IL-8. Interestingly, we also observed that infection of MUTZ cells with C. pneumoniae or C. trachomatis serovar L2, whilst not replicative, remained infectious and upregulated lymph node migratory marker CCR7 mRNA. Taken together, these data confirm the findings of other groups using primary DCs and demonstrate the utility of MUTZ cells for further studies of chlamydial infection.

Streptococcus pneumoniae infection suppresses allergic airways disease by inducing regulatory T-cells.

An inverse association exists between some bacterial infections and the prevalence of asthma. We investigated whether Streptococcus pneumoniae infection protects against asthma using mouse models of ovalbumin (OVA)-induced allergic airway disease (AAD). Mice were intratracheally infected or treated with killed S. pneumoniae before, during or after OVA sensitisation and subsequent challenge. The effects of S. pneumoniae on AAD were assessed. Infection or treatment with killed S. pneumoniae suppressed hallmark features of AAD, including antigen-specific T-helper cell (Th) type 2 cytokine and antibody responses, peripheral and pulmonary eosinophil accumulation, goblet cell hyperplasia, and airway hyperresponsiveness. The effect of infection on the development of specific features of AAD depended on the timing of infection relative to allergic sensitisation and challenge. Infection induced significant increases in regulatory T-cell (Treg) numbers in lymph nodes, which correlated with the degree of suppression of AAD. Tregs reduced T-cell proliferation and Th2 cytokine release. The suppressive effects of infection were reversed by anti-CD25 treatment. Respiratory infection or treatment with S. pneumoniae attenuates allergic immune responses and suppresses AAD. These effects may be mediated by S. pneumoniae-induced Tregs. This identifies the potential for the development of therapeutic agents for asthma from S. pneumoniae.

Interleukins and IgA synthesis. Human and murine interleukin 6 induce high rate IgA secretion in IgA-committed B cells.

Freshly isolated murine PP B cells were cultured with 10 different cytokines, including IL-1 alpha, IL-2, IL-4, IL-5, IL-6, IL-7, IFN-gamma, TNF-alpha, and TGF-beta, to investigate a possible role for these cytokines in induction of Ig synthesis. Of interest was the finding that only IL-5 and both mouse recombinant (mr) and human recombinant (hr) IL-6 enhanced IgA synthesis. The effect was greater with either mrIL-6 or hrIL-6 than with mrIL-5. IL-6 induced cycling mIgA+ PP B cells to secrete high levels of IgA (approximately 7-fold increase over control). Of importance was the finding that mrIL-6 had little effect on secretion of IgM or IgG by PP B cell cultures. hrIL-6 also increased IgA secretion by PP B cells and this enhancement was abolished by a goat anti-hrIL-6 antiserum. mrIL-6 did not cause B cell proliferation but induced a sharp increase in numbers of B cells secreting IgA. Isotype-switching was not a mechanism for this marked increase in IgA synthesis since mIgA- PP B cells were not induced to secrete IgA by mrIL-6. From these studies we conclude that IL-6 plays an important role in promoting the terminal differentiation of PP B cells to IgA-secreting plasma cells.

Granulocyte-macrophage colony-stimulating factor enhances wound healing in diabetes via upregulation of proinflammatory cytokines.

BACKGROUND: Chronic ulceration, especially in diabetes, remains a substantial clinical problem. Exogenous granulocyte-macrophage colony-stimulating factor (GM-CSF) is efficacious in the treatment of chronic wound healing in both animal models and patients, but its role in diabetic wounds remains to be explored. Objectives Using a diabetic mouse model, to investigate the role of GM-CSF in wound healing. METHODS: Clinical observation, histopathology, immunohistochemistry and cytokine assays. RESULTS: There was a significant reduction (50%) in GM-CSF production in the wounds of the diabetics compared with nondiabetics. Exogenous GM-CSF substantially enhanced the wound healing in diabetic mice, accompanied by increased interleukin-6 and monocyte chemoattractant protein-1 production. The elevated cytokines correlated with increased neovascularization, and infiltration of macrophages and neutrophils. GM-CSF showed no beneficial effects in nondiabetic wound healing. CONCLUSIONS: Our results provide useful guidelines for the clinical management of chronic ulceration in diabetes.

The role of granulocyte macrophage-colony stimulating factor in gastrointestinal immunity to salmonellosis.

Human Salmonella infection, in particular, typhoid fever is a highly infectious disease that remains a major public health problem causing significant morbidity and mortality. The outcome of these infections depends on the host's immune response, particularly the actions of granulocytes and macrophages. Using a mouse model of human typhoid fever, with Salmonella typhimurium infection of wild type and granulocyte macrophage-colony stimulating factor (GM-CSF) knock out mice we show a delay in the onset of immune-mediated tissue damage in the spleens and livers of GM-CSF(-/-) mice. Furthermore, GM-CSF(-/-) mice have a prolonged sequestration of S. typhimurium in affected tissues despite an increased production of F4/80+ effector cells. Moreover in the absence of GM-CSF, a decrease in pro-inflammatory cytokine expression of tumor necrosis factor-alpha, interleukin-12 (IL-12) and IL-18 was found, which may alter the host's immune response to infection. GM-CSF appears to play an important role in the pathogenesis of Salmonellosis, and may contribute significantly to the development of protective gastrointestinal mucosal immune responses against oral pathogens.

Human appendix B cells naturally express receptors for and respond to interleukin 6 with selective IgA1 and IgA2 synthesis.

Past studies have shown that freshly isolated human B cells from peripheral blood and tonsils do not express IL-6 receptors (IL-6R); however, mitogen or antigen activation of these B cells induces IL-6R and responsiveness to IL-6. In this study, we have shown that a high proportion of B cells enzymatically dissociated from human appendix, a gut-associated lymphoreticular tissue (GALT), expresses the IL-6R, and that recombinant human IL-6 induces significant increases in the number of Ig-producing cells. The recombinant human IL-6-induced increase in Ig-producing cells is restricted to the IgA isotype. Further, IgA2 is the major subclass; however, significant numbers of IgA1 producing cells are also seen. In contrast, human tonsillar and peripheral blood B cells express low levels of IL-6R, and exogenous IL-6 does not increase numbers of Ig-producing cells. When PBMC or tonsillar cells are stimulated with PWM, the former display an equal distribution of IgA1 and IgA2 secreting cells, while tonsillar B cells are mainly of the IgA1 subclass. The distribution of surface Ig-positive (sIg+) B cells in the appendix B cell population is sIgA+ greater than sIgG+ greater than sIgM+, and the sIgA+ B cells express higher levels of IL-6R when compared with sIgG+ or sIgM+ B cells. These studies show that human appendix contains B cell subsets that constitutively express IL-6R, and that a high proportion of these cells are committed to the IgA isotype. Furthermore, higher numbers of IL-6 responsive IgA2 B cells are present in the human appendix as compared to tonsils or PBMC.

Induction of partial immunity in both males and females is sufficient to protect females against sexual transmission of Chlamydia.

Sexually transmitted Chlamydia trachomatis causes infertility, and because almost 90% of infections are asymptomatic, a vaccine is required for its eradication. Mathematical modeling studies have indicated that a vaccine eliciting partial protection (non-sterilizing) may prevent Chlamydia infection transmission, if administered to both sexes before an infection. However, reducing chlamydial inoculum transmitted by males and increasing infection resistance in females through vaccination to elicit sterilizing immunity has yet to be investigated experimentally. Here we show that a partially protective vaccine (chlamydial major outer membrane protein (MOMP) and ISCOMATRIX (IMX) provided sterilizing immunity against sexual transmission between immunized mice. Immunizing male or female mice before an infection reduced chlamydial burden and disease development, but did not prevent infection. However, infection and inflammatory disease responsible for infertility were absent in 100% of immunized female mice challenged intravaginally with ejaculate collected from infected immunized males. In contrast to the sterilizing immunity generated following recovery from a previous chlamydial infection, protective immunity conferred by MOMP/IMX occurred independent of resident memory T cells. Our results demonstrate that vaccination of males or females can further protect the opposing sex, whereas vaccination of both sexes can synergize to elicit sterilizing immunity against Chlamydia sexual transmission.

Intraepithelial lymphocytes: origins, distribution, and function.

Intraepithelial lymphocytes (IEL) are associated with the intestinal tract, respiratory tract, genitourinary tract epithelium, and the skin and are the first immune system cells to encounter pathogens that have invaded an epithelial surface. IEL are predominantly T cells (CD3+) with CD8+ cells predominating at most, but not all, sites. Both TCR alphabeta+ and TCR gammadelta+ cells are found within IEL populations and an increasing body of evidence suggests that some IEL may arise extrathymically. The presence within intestinal IEL of cells expressing potentially self-reactive TCR suggests that T cell selection within epithelia may differ from thymic T cell selection although recent evidence suggests that these cells may in fact be nonresponsive. IEL exhibit various cytotoxic activities including alloreactive and virus-specific CTL activity, NK activity and spontaneous cytotoxicity, activities consistent with an immune surveillance or first line of defence role. IEL also appear activated in vivo and secrete a variety of cytokines. Subsets of IEL have been shown to provide B cell help, to play a role in the maintenance of oral tolerance and to regulate epithelial cell function. In this review the morphology, distribution and phenotype of IEL, the potential for extrathymic development and possible functions of this unique lymphoid population are discussed.

Dendritic cells from different tissues induce production of different T cell cytokine profiles.

The precise role of antigen-presenting cells (APC) in regulating the balance of T-helper type 1 (Th1) and T-helper type 2 (Th2) cytokine production is unclear. Dendritic cells (DC), the most potent APC for activation of naive T cells, were found to regulate Th1 and Th2 cytokine profiles in a fashion dependent upon their tissue of origin. Spleen (systemic) DC induce mainly Th1 cytokines and Peyer's patch (mucosal) DC induce predominantly Th2 cytokines. These findings support the current concept that different tissues, each with its distinct microenvironment of cytokines, hormones, and cellular elements, are involved in the selection, promotion, and/or maintenance of different immune responses. With regard to DC, it is apparent that the tissue of DC origin determines the cytokine profiles produced by T cells and that DC from different tissues favor either cellular versus humoral immune responses by influencing T cell cytokine production.

Transcutaneous immunization induces mucosal and systemic immunity: a potent method for targeting immunity to the female reproductive tract.

Female BALB/c mice were immunized with tetanus toxoid (TT) admixed with cholera toxin by direct application to shaved skin (Transcutaneous immunization, TCI). Tetanus toxoid-specific IgG and IgA in serum, saliva, vaginal lavage and fecal pellets were assayed by ELISA. Tetanus toxoid specific antibody-secreting cell (ASC) numbers were also determined by immunohistochemistry in sections of vagina, uterus, salivary gland and small intestine of immunized mice. TCI elicited significant levels of TT-specific IgG in serum, saliva and vaginal lavage, with the greatest increases over background seen in saliva (80-400 fold) and vaginal lavage (2-87 fold). TCI induced only modest levels of IgA in any of the samples tested (range 2-7 fold increase). In the absence of cholera toxin, application of TT alone did not result in detectable TT-specific antibodies in mucosal secretions. ASCs were found in all tissues following TCI. Cells were most frequent in uterus and vaginal tissues with ASC numbers less frequent in small intestine and salivary gland. This suggests that local production, rather than transudation from serum, is a major contributor of antibody in reproductive tract secretions. Further studies focussed on the role of sex hormones and immune induction following TCI. Animals immunized at the stage of oestrus cycle at which estrogen is abundant (Estrus), showed significantly lower levels of TT-specific IgG in vaginal lavage samples. Collectively, these data confirm the findings of Glenn and colleagues (1998), who showed TCI using cholera toxin can elicit high levels of serum IgG to both the toxin and co-administered antigen and further demonstrates that this route of immunization is particularly effective at eliciting humoral immunity in saliva and in the female reproductive tract.

New perspectives in mucosal immunity with emphasis on vaccine development.

In this review, we have purposely focused on five areas that are currently receiving extensive research attention and will be of major importance for development of mucosal and systemic immunity to oral vaccines. These five areas include the following: (1) helper T-cell (Th) subsets and cytokines for mucosal IgA responses; (2) Th1- and Th2-type subsets in regulation of mucosal IgA responses; (3) antigen uptake and presentation in the mucosal immune system; (4) the importance of memory in mucosal immunity to vaccines; and (5) the determination of whether oral immunization alone induces immunity in all mucosal effector tissues. It is now established that the mucosal immune system can be divided into discrete mucosal inductive sites where vaccines/antigens are encountered and taken up, processed, and presented to B and T cells, and separate areas where immune cells actually function (mucosal effector tissues). Further, through the help provided by Th cells and cytokines, the B cells respond to antigen and undergo expansion including memory cell formation. Following the migration of memory B cells to mucosal effector tissues, the cells rapidly develop into IgA plasma cells, and the prevalence of the latter cell type represents a major characteristic of mucosal effector tissues. It also appears that antigen-specific Th cells and perhaps even CD8+ cytotoxic T lymphocytes can make this circular journey (along with memory/activated B cells) from inductive to mucosal effector sites, and this is termed the common mucosal immune system (CMIS). The major implications of the CMIS for development of vaccines would include each of the five components that are discussed.

Dendritic cells from Peyer's patch and spleen induce different T helper cell responses.

The role of antigen-presenting cells (APC) in regulating the balance of T helper type 1 (Th1) and T helper type 2 (Th2) responses and cytokine production is unclear. Dendritic cells (DC), the most potent APC for naive T cell activation, were found to regulate Th1 and Th2 cytokine profiles in a manner dependent on their tissue of origin. Using whole tissues or purified cell mixtures, spleen (systemic) DC were found to induce mainly Th1 cytokines, and Peyer's patch (mucosal) DC were found to induce predominantly Th2 cytokines. Spleen DC induced high levels of interferon-gamma (IFN-gamma) or interleukin-2 (IL-2) or both, and Peyer's patch DC induced IL-4 or IL-6 or both in spleen and Peyer's patch T cells, allogeneic mixed leukocyte reactions, or antigen-specific Th0 clones. These data suggest that the tissue of origin of DC has a significant impact on subsequent T cell development.

Role of interleukin-6 in human and mouse mucosal IgA plasma cell responses.

In summary, we have shown that human appendix and murine PP B cells, freshly isolated from normal tissue, respond IL-6 with significant increases in IgA SFC. Further, sIgA+ B cells from appendix express more IL-6R than is seen with B cells isolated from PBMC and spleen. When IgA subclass responses were measured, rhIL-6 induced both IgA1 and IgA2 SFC responses; however, 60-70% of the total response was represented by the IgA2 subclass. Our studies suggest that the human appendix as well as murine PP are enriched sources for sIgA+ B cells which are responsive to cytokines such as IL-6 for induction of IgA plasma cell responses.

Detection of individual mouse splenic T cells producing IFN-gamma and IL-5 using the enzyme-linked immunospot (ELISPOT) assay.

Although several sensitive and specific assays have been developed to quantify murine cytokines, these assays do not allow individual cells to be correlated with the specific cytokines they produce. The purpose of this study was to develop a sensitive and reproducible method for the detection of individual T cells which secrete either interferon-gamma (IFN-gamma) or interleukin-5 (IL-5). We have used an adaptation of the enzyme-linked immunospot (ELISPOT) assay in which monoclonal antibodies to IFN-gamma (R4-6A2) and to IL-5 (TRFK-5) were used to coat 96-well plates with a nitrocellulose base. Mouse splenic T cells, either nonstimulated or activated with concanavalin A (ConA) or phytohemagglutinin (PHA), were cultured in individual wells. Following incubation, the cells were removed, and the bound cytokines probed with either biotinylated mAb anti-IFN-gamma (XMG 1.2) or anti-IL-5 (TRFK-4) followed by avidin-peroxidase. The spots which developed with 3-amino-9-ethylcarbazole were discrete and enumerated with a dissecting microscope. Although unstimulated splenic T cells contained low numbers of cytokine-specific spot-forming cells (SFC), 24-72 h activation with mitogen was required to induce significant numbers of cytokine producing cells. When mitogen-stimulated splenic CD4+ T cells were assessed, approximately equal numbers of IFN-gamma and IL-5 SFC were seen. Approximately 20-30% of all mitogen-activated splenic T cells produced at least one of these two cytokines. Pre-incubation of biotinylated anti-IFN-gamma with recombinant IFN-gamma (rIFN-gamma) or anti-IL-5 mAbs with rIL-5 completely inhibited cytokine-specific SFC. Further, use of nonrelevant antibodies did not result in spot formation, and treatment of mitogen-activated T cells with cycloheximide inhibited both IFN-gamma- and IL-5-specific SFC. A sensitive method has been developed which allows detection of individual T cells that produce either IFN-gamm or IL-5, and should be useful for detection of cytokine secretion at the single cell level.

Cytokine-specific ELISPOT assay. Single cell analysis of IL-2, IL-4 and IL-6 producing cells.

In order to assess cytokine-producing cells at the single cell level, the cytokine-specific ELISPOT assay has proven to be an important and sensitive method. The purpose of this study was to adapt this method to elucidate individual cells producing murine IL-2, IL-4 or IL-6. In order to establish these cytokine-specific ELISPOT assays, IL-2-, IL-4- and IL-6-specific cDNA transfected myeloma cell lines, e.g., X63-Ag8-653 X2, X63-Ag8-653 X4 and X63-Ag8-653 X6, respectively, were used as specific cytokine-producing cells. In the IL-2 ELISPOT assay, the coating reagent, monoclonal antibody (mAb) rat IgG2a anti-mouse IL-2 (CR #40014) was used while rabbit IgG polyclonal anti-mouse IL-2 was employed for detection of IL-2 spot forming cells (SFC). The mAbs anti-mouse IL-4, BVD4-1D11 and BVD6-24G2 were selected as capture and detection antibodies for enumeration of IL-4 SFC. For the IL-6 ELISPOT assay, anti-mouse IL-6 (MP5-20F3) mAb was used for coating and MP5-32C11 mAb was used for detection of IL-6 SFC. When IL-2 producing X63-Ag8-653 X2 cells were subjected to these three different ELISPOT assays, IL-2-specific SFC were only noted with the IL-2 ELISPOT system. In the case of IL-4 SFC, only X63-Ag8-653 X4 cells formed specific spots using the tandem of BVD4-1D11 and BVD6-24G2 mAbs. IL-6-specific spots developed in MP5-20F3 mAb pre-coated wells containing X63-Ag8-653 X6 cells, when developed with mAb anti-IL-6 (MP5-32C11). Addition of cycloheximide (50 micrograms/ml) inhibited formation of IL-2, IL-4 and IL-6 SFC by approximately 90%. When an unrelated mAb was used as detection antibody in these three different cytokine-specific ELISPOT assays, IL-2-, IL-4- and IL-6-specific SFC were not detected. Further, when concanavalin A stimulated T cells from Peyer's patch of normal mice were subjected to the respective cytokine-specific ELISPOT assay, IL-2, IL-4 and IL-6 SFC were enumerated. These results have shown that cytokine-specific IL-2, IL-4 and IL-6 ELISPOT assays have now been established and will allow analysis of the frequency of cytokine-secreting cells at the single cell level.

Immunoregulatory confluence: T cells, Fc receptors and cytokines for IgA immune responses.

IgA isotype responses are regulated by at least two compartments including those of CD4+ Th2 type cells and cytokines produced by these cells. Interaction of CD4+ Th cells and APC via TCR and Ag-MHC II leads to activation of Th2 type cells. This would allow for secretion of cytokines, especially IL-5 and IL-6 which are key cytokines for the terminal differentiation of B cells into Ig secreting cells. Further, expression of Fc alpha RII on CD4+ Th2 cells could be important for the recruitment of sIgA+ B cells which would allow selective interactions of Th2 cells and sIgA + B cells via Fc alpha RII. This could lead to selectively transfer of IL-5 and IL-6 to sIgA + B cells from CD4+ Th2 cells.

The effect of immunosuppressive agents on monocyte generation and cytokine expression.

SUMMARY: : The purpose of this study was to determine the effect of immunosuppressive drugs on the production of inflammatory cytokines and on the generation of macrophages from bone marrow precursors. Lipopolysaccharide-stimulated peripheral blood mononuclear cells (PBMCs) were cultured in the presence of therapeutic concentrations of 6-mercaptopurine (6-MP), methotrexate (MTX), or prednisolone. The effect of these drugs on the expression of interleukin (IL)-lß, IL-8, and tumor necrosis factor-α (TNF-α) was studied using bioassays and Northern analysis. The generation of monocytes/macrophages from precursors in the bone marrow was examined by culturing murine bone marrow cells with macrophage colony-stimulating factor (M-CSF) in the presence or absence of these agents. 6-MP and MTX did not inhibit the production or messenger RNA (mRNA) expression of the macrophage-derived cytokines, although prednisolone did. Both 6-MP and MTX substantially decreased the generation of macrophages from bone marrow precursors. We conclude that the beneficial effects of these immunosuppressive agents might be due to the suppression of the generation of monocytes in the bone marrow precursors, secondarily diminishing the production of cytokines, eicosanoids, and the production of free radicals.

Chlamydia trachomatis infection: incidence, health costs and prospects for vaccine development.

Chlamydia trachomatis infection is now the most common sexually transmitted disease worldwide. World Health Organisation figures estimated that 89 million new cases of genital Chlamydia infections occurred in 1995, highlighting the worldwide prevalence of infections and the economic burden on healthcare delivery. A number of methods have been developed for detection of chlamydial infection, which vary in sensitivity and specificity. No single method has yet gained general acceptance and in many countries Chlamydia infections are not reported, suggesting that the above figures may be an underestimate of the problem. As yet there is no consensus as to what constitutes a protective immune response against genital Chlamydia infection. Studies in animal models have shown that cell-mediated immunity, both Th1-driven macrophage activation and cytotoxic T cell responses, as well as antibody can mediate protection at different stages of the chlamydial life cycle. A successful vaccine would probably need to elicit both a systemic cell-mediated immune response to limit/resolve established infections and a mucosal IgA response to reduce bacterial shedding and the resulting spread of infection to partners of infected individuals. The immune response to Chlamydia, either through natural infection or following immunisation, also has the potential to enhance inflammation and to act as a driving force for constant mutation in the variable regions of the major outer membrane protein. As a result a constant prevalence of infection is maintained even in an immune population through the emergence of new allelic variants. Immune responses against antigens such as the 60 kDa heat shock protein can exacerbate inflammation through molecular mimicry and must not be elicited as a result of vaccination. Thus there are many challenges for the development of a successful vaccine which must elicit immunity against multiple serovars while at the same time minimising damaging pro-inflammatory immune responses.

Increased severity of Candida vaginitis in BALB/c nu/nu mice versus the parent strain is not abrogated by adoptive transfer of T cell enriched lymphocytes.

The role of the host immune system in combating candidal infections in the vagina is poorly understood. A murine model of Candida vaginitis was used to elucidate the role of T cells in a candidal infection. Athymic BALB/c nu/nu mice or normal BALB/c mice were induced into estrus and then infected with 1 x 10(6) Candida albicans intravaginally. The infection was monitored over 1 week. Samples from blood, small intestine, tongue, kidney, spleen, liver, uterus and vagina were tested for recoverable C. albicans. Histology of the vagina was assessed for both inflammation and extent of infection. Results indicated that the BALB/c nu/nu mice had similar levels of vaginal yeast load to the normal BALB/c mice. In 25-30% of nude mice Candida was also recovered from extra vaginal sites (kidney, liver, small intestine), however, extra vaginal dissemination was not observed in any normal BALB/c animals. Histologically, both the nu/nu and control BALB/c had similar levels of vaginal inflammation; however, the nu/nu mice had more florid fungal growth in the vaginal epithelium. Adoptive transfer of either immune or non-immune BALB/c T cells into nude mice had no affect on either infection or vaginal inflammation. Immunohistochemical staining of vaginal tissues from normal BALB/c mice or nude mice adoptively transferred with either immune or non-immune T cells with anti-CD3 monoclonal antibody revealed no significant difference between groups in the numbers of CD3+ vaginal T cells. However, in mice receiving either immune or non-immune T cells no yeast was recovered from any tissues except the vagina. These data show that T cells have a limited role in protecting the vagina from C. albicans infection.

Protection against Helicobacter pylori infection by intestinal immunisation with a 50/52-kDa subunit protein.

A mouse model of Helicobacter pylori infection was used to evaluate the vaccine antigen potential of the citrate synthase homologue protein purified from the H. pylori NCTC 11637 strain. Mice were immunised with the protein by intra-Peyer's patch immunisation. This route gives maximal intestinal immunisation and was used to screen oral vaccine candidate antigens without the added complication of simultaneously testing oral delivery systems. Two weeks post-immunisation mice were infected with Sydney strain H. pylori and 4 weeks after infection the mice were killed and the level of H. pylori infection in the stomach determined. Pre-immunisation with the 50/52-kDa protein led to a 84-91% reduction in H. pylori infection compared to unimmunised controls.