Systemic and secretory humoral immunity in the normal human vaginal tract

Hexavalent sperm-binding IgG antibody released from vaginal film for development of potent on-demand nonhormonal female contraception

Nearly half of all pregnancies in the United States are unintended due to millions of women avoiding available hormonal contraceptive methods as a result of real and/or perceived side effects associated with the use of exogenous hormones. Topical vaginal delivery of antisperm monoclonal antibodies that could agglutinate sperm into clusters too large to penetrate mucus and prevent sperm from reaching the egg represents a potentially safe and potent mechanism for nonhormonal contraception. We report here the engineering of a vaginal film loaded with hexavalent (i.e., 6 Fab) antisperm IgG, made using GMP manufacturing processes, that possesses significantly superior agglutination potency than the parent IgG, enabling potent on-demand nonhormonal contraception via effectively agglutinating all human sperm within minutes.

Nonhormonal products for on-demand contraception are a global health technology gap; this unmet need motivated us to pursue the use of sperm-binding monoclonal antibodies to enable effective on-demand contraception. Here, using the cGMP-compliant Nicotiana-expression system, we produced an ultrapotent sperm-binding IgG antibody possessing 6 Fab arms per molecule that bind a well-established contraceptive antigen target, CD52g. We term this hexavalent antibody “Fab-IgG-Fab” (FIF). The Nicotiana-produced FIF had at least 10-fold greater sperm-agglutination potency and kinetics than the parent IgG, while preserving Fc-mediated trapping of individual spermatozoa in mucus. We formulated the Nicotiana-produced FIF into a polyvinyl alcohol–based water-soluble contraceptive film and evaluated its potency in reducing progressively motile sperm in the sheep vagina. Two minutes after vaginal instillation of human semen, no progressively motile sperm were recovered from the vaginas of sheep receiving FIF Film. Our work supports the potential of multivalent contraceptive antibodies to provide safe, effective, on-demand nonhormonal contraception.

An IgA mimicry of IgG that binds Polymeric Immunoglobulin Receptor for mucosa transcytosis

Most pathogens establish infection through mucosa, where secretary IgA (sIgA) plays an "immune exclusion" role in humoral defense. Extravasation of intravenously administrated therapeutic IgG mainly relies on convection and/or FcRn-mediated transcytosis from circulation into interstitial space. Active transport of interstitial IgG further across epithelium into mucosa, like sIgA, is a much desired feature for the next generation of therapeutic antibodies, especially for anti-infection purposes. For the first time, we report the engineering of an IgA mimicry of IgG, with its Fc portion in fusion with the 18-aa tail piece (tp) of sIgA and the J chain, possessing sIgA's full binding activity towards Polymeric Immunoglobulin Receptor (pIgR) that mediates mucosa transcytosis. In a Diphtheria toxin receptor (DTR) knockin mouse model, i.v. injected anti-DT IgG(tp)J protected DTR+ cells from deletion upon DT injection. The compact design of IgG(tp)J opens new revenues for more effective therapeutic IgG mimicking some of the important biological functions of IgA.

Hepatitis B Vaccination Induces Mucosal Antibody Responses in the Female Genital Tract, Indicating Potential Mechanisms of Protection Against Infection

Vaccines against hepatitis B virus confer effective protection. Enzyme-linked immunosorbent assay was developed to test for specific antibodies in female genital tract secretions. Anti-hepatitis B IgG and IgA were detected in the cervicovaginal secretions of women after hepatitis B vaccination, indicating a potential genital tract role for neutralizing antibodies against sexually transmitted hepatitis B virus.

Natural and vaccine-induced B cell-derived systemic and mucosal humoral immunity to human papillomavirus

Introduction: Human papillomavirus (HPV) are the causative agent of mucosal neoplasia. Both cervical, anal and oropharyngeal cancers incidence is constantly increasing, making the HPV infection, a significant worldwide concern. Together, the CD8+ T cytotoxic cell-mediated response and the HPV-specific antibody response control most of the HPV infections before the development of cancers.Areas covered: We searched the MEDLINE and EMBASE databases and identified 228 eligible studies from 1987 to 2019 which examines both naturally acquired and vaccine induced humoral immunity against HPV infection in female and male subjects from worldwide origin. Herein, we synthesize current knowledge on the features of systemic and mucosal humoral immunity against HPV. We discuss the issues of the balance between the viral clearance or the escape to the host immune response, the differences between natural and vaccine-induced HPV-specific antibodies and their neutralizing capability. We also discuss the protection afforded after natural infection or following prophylactic vaccination.Expert opinion: Understanding the antibody response induced by HPV infection has led to the design of first-generation prophylactic vaccines. Now, prophylactic vaccination induces protective and long-lasting antibody response which would also strengthened the natural moderate humoral response in people previously exposed to the virus.

Virus-like particle vaccines: immunology and formulation for clinical translation

INTRODUCTION

Virus-like particle (VLP) vaccines face significant challenges in their translation from laboratory models, to routine clinical administration. While some VLP vaccines thrive and are readily adopted into the vaccination schedule, others are restrained by regulatory obstacles, proprietary limitations, or finding their niche amongst the crowded vaccine market. Often the necessity to supplant an existing vaccination regimen possesses an immediate obstacle for the development of a VLP vaccine, despite any preclinical advantages identified over the competition. Novelty, adaptability and formulation compatibility may prove invaluable in helping place VLP vaccines at the forefront of vaccination technology.

AREAS COVERED

The purpose of this review is to outline the diversity of VLP vaccines, VLP-specific immune responses, and to explore how modern formulation and delivery techniques can enhance the clinical relevance and overall success of VLP vaccines.

EXPERT COMMENTARY

The role of formation science, with an emphasis on the diversity of immune responses induced by VLP, is underrepresented amongst clinical trials for VLP vaccines. Harnessing such diversity, particularly through the use of combinations of select excipients and adjuvants, will be paramount in the development of VLP vaccines.

Cervico-vaginal immunoglobulin G levels increase post-ovulation independently of neutrophils

The prevalence of sexually transmitted infections (STIs) is often higher in females than in males. Although the reproductive cycle profoundly modulates local immunity in the female reproductive tract (FRT) system, significant gaps in our knowledge of the immunobiology of the FRT still exist. An intriguing and frequently observed characteristic of the FRT is the predominant presence of immunoglobulin (Ig) G in cervico-vaginal secretions. We show here that in the mouse, IgG accumulation was enhanced approximately 5-fold post-ovulation, and was accompanied by an influx of neutrophils into the FRT. To determine whether these two events were causally related, we performed short-term neutrophil depletion experiments at individual stages throughout the estrous cycle. Our results demonstrate that neutrophils were not necessary for cycle-dependent tissue remodeling and cycle progression and that cycle-dependent IgG accumulation occurred independent of neutrophils. We thus conclude that neutrophil influx and IgG accumulation are independent events that occur in the FRT during the reproductive cycle.

Adaptive HIV-specific B cell-derived humoral immune defenses of the intestinal mucosa in children exposed to HIV via breast-feeding

Background

We evaluated whether B cell-derived immune defenses of the gastro-intestinal tract are activated to produce HIV-specific antibodies in children continuously exposed to HIV via breast-feeding.

Methods

Couples of HIV-1-infected mothers (n = 14) and their breastfed non HIV-infected (n = 8) and HIV-infected (n = 6) babies, and healthy HIV-negative mothers and breastfed babies (n = 10) as controls, were prospectively included at the Complexe Pédiatrique of Bangui, Central African Republic. Immunoglobulins (IgA, IgG and IgM) and anti-gp160 antibodies from mother’s milk and stools of breastfed children were quantified by ELISA. Immunoaffinity purified anti-gp160 antibodies were characterized functionally regarding their capacity to reduce attachment and/or infection of R5- and X4- tropic HIV-1 strains on human colorectal epithelial HT29 cells line or monocyte-derived-macrophages (MDM).

Results

The levels of total IgA and IgG were increased in milk of HIV-infected mothers and stools of HIV-exposed children, indicating the activation of B cell-derived mucosal immunity. Breast milk samples as well as stool samples from HIV-negative and HIV-infected babies exposed to HIV by breast-feeding, contained high levels of HIV-specific antibodies, mainly IgG antibodies, less frequently IgA antibodies, and rarely IgM antibodies. Relative ratios of excretion by reference to lactoferrin calculated for HIV-specific IgA, IgG and IgM in stools of HIV-exposed children were largely superior to 1, indicating active production of HIV-specific antibodies by the intestinal mucosa. Antibodies to gp160 purified from pooled stools of HIV-exposed breastfed children inhibited the attachment of HIV-1NDK on HT29 cells by 63% and on MDM by 77%, and the attachment of HIV-1JRCSF on MDM by 40%; and the infection of MDM by HIV-1JRCSF by 93%.

Conclusions

The intestinal mucosa of children exposed to HIV by breast-feeding produces HIV-specific antibodies harbouring in vitro major functional properties against HIV. These observations lay the conceptual basis for the design of a prophylactic vaccine against HIV in exposed children.

How can HIV-type-1-Env immunogenicity be improved to facilitate antibody-based vaccine development?

No vaccine candidate has induced antibodies (Abs) that efficiently neutralize multiple primary isolates of HIV-1. Preexisting high titers of neutralizing antibodies (NAbs) are essential, because the virus establishes infection before anamnestic responses could take effect. HIV-1 infection elicits Abs against Env, Gag, and other viral proteins, but of these only a subset of the anti-Env Abs can neutralize the virus. Whereas the corresponding proteins from other viruses form the basis of successful vaccines, multiple large doses of HIV-1 Env elicit low, transient titers of Abs that are not protective in humans. The inaccessibility of neutralization epitopes hinders NAb induction, but Env may also subvert the immune response by interacting with receptors on T cells, B cells, monocytes, macrophages, and dendritic cells. Here, we discuss evidence from immunizations of different species with various modified Env constructs. We also suggest how the divergent Ab responses to Gag and Env during infection may reflect differences in B cell regulation. Drawing on these analyses, we outline strategies for improving Env as a component of a vaccine aimed at inducing strong and sustained NAb responses.

Humoral immunogenicity of an HIV-1 envelope residue 649-684 membrane-proximal region peptide fused to the plague antigen F1-V

The membrane-proximal region spanning residues 649-684 of the HIV-1 envelope protein gp41 (MPR₆₄₉₋₆₈₄) is an attractive vaccine target for humoral immunity that blocks viral transcytosis across the mucosal epithelia. However, induction of high-titer MPR₆₄₉₋₆₈₄-specific antibodies remains a challenging task. To explore potential solutions for this challenge, we tested a new translational fusion protein comprising the plague F1-V antigen and MPR₆₄₉₋₆₈₄ (F1-V-MPR₆₄₉₋₆₈₄). We employed systemic immunization for initial feasibility analyses. Despite strong immunogenicity demonstrated for the immunogen, repeated systemic immunizations of mice with F1-V-MPR₆₄₉₋₆₈₄ hardly induced MPR₆₄₉₋₆₈₄-specific IgG. In contrast, a single immunization with F1-V-MPR₆₄₉₋₆₈₄ mounted a significant anti-MPR₆₄₉₋₆₈₄ IgG response in animals that were primed with another MPR₆₄₉₋₆₈₄ fusion protein based on the cholera toxin B subunit. Additional boost immunizations with F1-V-MPR₆₄₉₋₆₈₄ recalled and maintained the antibody response and expanded the number of specific antibody-secreting B cells. Thus, while F1-V-MPR₆₄₉₋₆₈₄ alone was not sufficiently immunogenic to induce detectable levels of MPR₆₄₉₋₆₈₄-specific antibodies, these results suggest that prime-boost immunization using heterologous antigen-display platforms may overcome the poor humoral immunogenicity of MPR₆₄₉₋₆₈₄ for the induction of durable humoral immunity. Further studies are warranted to evaluate the feasibility of this strategy in mucosal immunization. Lastly, our findings add to a growing body of evidence in support of this strategy for immunogen design for poorly immunogenic epitopes besides the MPR of HIV-1's transmembrane envelope protein.

Molecular characterization of the cervical and systemic B-cell repertoire: Unique, yet overlapping, immune compartments of an HIV-1 resistant individual

The cervical mucosa of women who are highly exposed to HIV-1, yet remain persistently seronegative (HEPS), presents a unique opportunity to study the dynamics of an immune compartment potentially capable of preventing HIV-1 infection. Herein, we provide a detailed characterization of the immunoglobulin repertoire of cervical and systemic B cells from one such HEPS individual from Nairobi, Kenya. Analysis was done on 512 VH sequences that were RT-PCR amplified from B cells in a paired sample from the cervix and peripheral blood. The VH3 and DH repertoire of class switched cervical B cells differs significantly from that of systemic B cells indicating that the cervical environment affects local B cell populations and hence VH gene expression. Six networks of clonally related, heavily mutated B cells were identified that spanned the systemic and cervical B cell compartments. Analysis of somatic mutations suggests this is likely the result of systemic, class switched B cells homing to the cervical mucosa. Multiple networks of somatically mutated V-gene sequences, unique to the cervical mucosa, were also identified. This supports the notion that site specific responses occur and have unique regulation of tolerance and recruitment into local memory or blast B cell compartments. We conclude that while the nature of the cervical environment shapes the local B cell repertoire, the infusion of post germinal center B cells to the human cervix is a common occurrence, and represents a means by which systemic immunization could provide the local antibodies necessary to prevent HIV-1 at the site of initial contact.

Infection of macrophages and dendritic cells with primary R5-tropic human immunodeficiency virus type 1 inhibited by natural polyreactive anti-CCR5 antibodies purified from cervicovaginal secretions

Heterosexual contact is the primary mode of human immunodeficiency virus (HIV) type 1 (HIV-1) transmission worldwide. The chemokine receptor CCR5 is the major coreceptor that is associated with the mucosal transmission of R5-tropic HIV-1 during sexual intercourse. The CCR5 molecule is thus a target for antibody-based therapeutic strategies aimed at blocking HIV-1 entry into cells. We have previously demonstrated that polyreactive natural antibodies (NAbs) from therapeutic preparations of immunoglobulin G and from human breast milk contain NAbs directed against CCR5. Such antibodies inhibit the infection of human macrophages and T lymphocytes by R5-tropic isolates of HIV in vitro. In the present study, we demonstrate that human immunoglobulins from the cervicovaginal secretions of HIV-seronegative or HIV-seropositive women contain NAbs directed against the HIV-1 coreceptor CCR5. Natural affinity-purified anti-CCR5 antibodies bound to CCR5 expressed on macrophages and dendritic cells and further inhibited the infection of macrophages and dendritic cells with primary and laboratory-adapted R5-tropic HIV but not with X4-tropic HIV. Natural anti-CCR5 antibodies moderately inhibited R5-tropic HIV transfer from monocyte-derived dendritic cells to autologous T cells. Our results suggest that mucosal anti-CCR5 antibodies from healthy immunocompetent donors may hamper the penetration of HIV and may be suitable for use in the development of novel passive immunotherapy regimens in specific clinical settings of HIV infection.

Vaccine adjuvant systems containing monophosphoryl lipid A and QS21 induce strong and persistent humoral and T cell responses against hepatitis B surface antigen in healthy adult volunteers

A randomised, double-blind study assessing the potential of four adjuvants in combination with recombinant hepatitis B surface antigen has been conducted to evaluate humoral and cell-mediated immune responses in healthy adults after three vaccine doses at months 0, 1 and 10. Three Adjuvant Systems (AS) contained 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and QS21, formulated either with an oil-in-water emulsion (AS02B and AS02V) or with liposomes (AS01B). The fourth adjuvant was CpG oligonucleotide. High levels of antibodies were induced by all adjuvants, whereas cell-mediated immune responses, including cytolytic T cells and strong and persistent CD4(+) T cell response were mainly observed with the three MPL/QS21-containing Adjuvant Systems. The CD4(+) T cell response was characterised in vitro by vigorous lymphoproliferation, high IFN-gamma and moderate IL-5 production. Antigen-specific T cell immune response was further confirmed ex vivo by detection of IL-2- and IFN-gamma-producing CD4(+) T cells, and in vivo by measuring increased levels of IFN-gamma in the serum and delayed-type hypersensitivity (DTH) responses. The CpG adjuvanted vaccine induced consistently lower immune responses for all parameters. All vaccine adjuvants were shown to be safe with acceptable reactogenicity profiles. The majority of subjects reported local reactions at the injection site after vaccination while general reactions were recorded less frequently. No vaccine-related serious adverse event was reported. Importantly, no increase in markers of auto-immunity and allergy was detected over the whole study course. In conclusion, the Adjuvant Systems containing MPL/QS21, in combination with hepatitis B surface antigen, induced very strong humoral and cellular immune responses in healthy adults. The AS01B-adjuvanted vaccine induced the strongest and most durable specific cellular immune responses after two doses. These Adjuvant Systems, when added to recombinant protein antigens, can be fundamental to develop effective prophylactic vaccines against complex pathogens, e.g. malaria, HIV infection and tuberculosis, and for special target populations such as subjects with an impaired immune response, due to age or medical conditions.

Comprehensive Proteomic Analysis of Human Cervical−Vaginal Fluid

Cervical-vaginal fluid (CVF) is a potential rich source of biomarkers for enhancing our understanding of human parturition and pathologic conditions affecting pregnancy. In this study, we performed a comprehensive survey of the CVF proteome in pregnancy utilizing multidimensional liquid chromatography (2D-LC) coupled with mass spectrometry and gel-electrophoresis-based protein separation and identification. In total, 150 unique proteins were identified using multiple protein identification algorithms. Metabolism (32%) and immune response-related (22%) proteins are the major functional categories represented in the CVF proteome. A comparison of the CVF, serum, and amniotic fluid proteomes showed that 77 proteins are unique to CVF, while 56 and 17 CVF proteins also occur in serum and amniotic fluid, respectively. This data set provides a foundation for evaluation of these proteins as potential CVF biomarkers for noninvasive diagnosis of pregnancy-related disorders.

Immunoglobulin levels and phagocytes in the cervical mucus plug at term of pregnancy

BACKGROUND

To characterize the potential for adaptive immune protection in cervical mucus plugs with respect to immunoglobulin isotypes and effector cells (phagocytes).

METHODS

Thirty-one cervical mucus plugs were collected from healthy women in labor at term. The cervical mucus plugs were allocated either to analysis of immunoglobulins by enzyme-linked immunosorbent assay (ELISA), gel chromatography and Western blotting (n = 20) or to microscopical, including immunocytochemical, analyses. The levels of immunoglobulin in the plugs were compared to the levels in 10 samples of ovulatory cervical mucus from nonpregnant women.

RESULTS

In the cervical mucus plugs, levels of immunoglobulin G (IgG) [median 3270 microg/mL (100-14 500)] and IgA [540 (22-2820)], but not IgM [30.5 (1.0-160)], were significantly elevated compared to cervical mucus from nonpregnant women (p < 0.02 for IgG and IgA). The IgG : IgA ratio in the plugs was also elevated (p < 0.02). The proportion of secretory immunoglobulin A (SIgA) relative to total IgA in the plugs ranged from 16 to 65% (n = 5). IgA and IgG were largely intact. Microscopically, the vagina-proximal part of the cervical mucus plugs contained bacteria and was rich in cells, mainly phagocytes. Conversely, the uterine part contained few cells.

CONCLUSION

The high immunoglobulin levels in combination with the presence of phagocytes suggest a potential for adaptive immune defense in the cervical mucus plug, which, together with innate immune factors, may act as an immunological gatekeeper protecting the fetomaternal unit against infection from the vagina.

High-Risk Papillomavirus Infection Is Associated with Altered Antibody Responses in Genital Tract: Non-specific Responses in HPV Infection

In order to gain more information about local humoral immune responses to HPV infection, we quantified IgG, IgM, secretory-IgA (S-IgA), and total-IgA by ELISA, and lysozyme and lactoferrin by TR-IFMA, in cervical and cervicovaginal secretions of 40 healthy women and 28 high-risk HPV infected patients (11 were HPV16+). IgG, total-IgA, and S-IgA concentrations in cervicovaginal secretions (p < 0.0001) and high IgG and total-IgA concentrations (p < 0.001 and p < 0.01, respectively) in endocervical secretions were significantly higher in HPV+ patients than in the healthy group. Since the S-IgA/total-IgA ratio was significantly lower in cervicovaginal (7.5%) and endocervical secretions (36.5%) in HPV+ women compared to the control group (p < 0.003 and p < 0.001, respectively), HPV could be responsible for an increase in local production of non-secretory IgA (monomeric and dimeric forms). IgG and total-IgA concentrations in cervicovaginal and endocervical secretions fell in the same general percentage range in both HPV16+ and HPV+ groups (80% and 15%, respectively). However, the S-IgA/total-IgA ratio was much lower in HPV16+ than in HPV+ women, in both cervicovaginal secretions (3.4%) (p < 0.003) and in endocervical secretions (23.3%) (p < 0.001). Innate immunity proteins and local S-IgA response could not stop the spread of HPV infection in spite of high lysozyme and lactoferrin concentrations. HPV16+ disturbed the local humoral immune system, which could partly explain its low clearance.

Specific antibody levels at the cervix during the menstrual cycle of women vaccinated with human papillomavirus 16 virus-like particles

BACKGROUND

In early-phase trials, a human papillomavirus 16 (HPV16) virus-like particle (VLP) vaccine has been shown to be well tolerated, immunogenic, and protective against HPV16 in women, most of whom were taking oral contraceptives. Previous studies have not determined whether HPV immunization results in specific antibody levels in the human genital tract or whether these levels might vary during contraceptive or ovulatory cycles. Therefore, we determined the levels of total and specific antibodies in the cervical secretions of women who had been immunized with HPV16 VLPs and examined the influence of the menstrual cycle and oral contraceptive use on these levels.

METHODS

Two groups of women were immunized, seven who were taking oral contraceptives and 11 who were ovulating. After seroconversion, serum and cervical secretions were collected twice weekly for 5 weeks. Total immunoglobulins (IgG and IgA) and vaccine-specific IgGs were determined by enzyme-linked immunosorbent assay. Nonparametric statistical analyses were used to determine the statistical significance of differences in IgG levels between groups, and correlations between serum- and cervical-specific IgG levels were determined by the Spearman correlation coefficient.

RESULTS

All participants developed detectable titers of anti-HPV16 VLP IgGs in their cervical secretions after immunization. The cervical titers of specific IgG and total IgGs and IgAs among participants in the contraceptive group were relatively constant throughout the contraceptive cycle. In contrast, the cervical titers of specific IgG and total IgGs and IgAs among participants in the ovulatory group varied during the menstrual cycle, being highest during the proliferative phase, decreasing approximately ninefold around ovulation, and increasing approximately threefold during the luteal phase. Serum- and cervical-specific IgG levels were correlated (r =.86) in women in the contraceptive group but not in women in the ovulatory group (r =.27).

CONCLUSIONS

The relatively high titer of anti-HPV16 antibodies at the cervix is promising in terms of vaccine efficacy; however, the decrease in antibody titer around ovulation raises the possibility that the HPV16 VLP vaccine might be less effective during the peri-ovulatory phase.

Mucosal humoral immune response to hepatitis C virus E1/E2 surface glycoproteins and HCV shedding in saliva and cervicovaginal fluids from chronically HCV-infected patients

BACKGROUND/AIMS

We herein focused on identifying biological factors possibly involved in non-parenteral transmission of hepatitis C virus (HCV), such as HCV excretion patterns and antibody-based immunity to the virus in saliva and/or cervicovaginal secretions (CVS).

METHODS

Paired blood, saliva and cervicovaginal lavage samples were obtained from HCV-RNA plasma-positive hemoglobin (Hb) antigen and HIV-seronegative, HCV-seropositive males (n=13) and females (n=21). HCV-specific antibodies were detected by ELISA in paired samples, and HCV-RNA was detected in cell-free and cell-associated body fluids.

RESULTS

Antibodies to E1 HCV surface glycoprotein of the IgG and IgA isotypes showed similar, but less pronounced, profiles as IgG and IgA to E2. HCV-specific IgG and IgA in mucosal fluids likely originated predominantly from the systemic compartment, because HCV-specific mucosal immunoglobulins involved primarily monomeric antibodies, including monomeric IgA, and because their specific activities for HCV antigens in corporeal fluids were similar to those in paired serum (Se). Viral shedding in saliva or CVS was restricted to cell-associated, non-replicating strand((+)) HCV-RNA in 42% (12 out of 28) of saliva and in 19% (four out of 21) of cervicovaginal fluids.

CONCLUSIONS

The association in body fluids of HCV-specific IgG, and to a lesser extent IgA, directed to E1/E2 surface glycoproteins (which may block critical steps of virus-cell interactions), of undetectable free viral RNA, and of occasional non-replicating cell-associated HCV, suggests a resulting poor infectivity of saliva or cervicovaginal fluid in chronically HCV-infected individuals. Taken together, these observations provide the basis for the low risk of non-parenteral transmission of HCV infection.

Cervicovaginal neutralizing antibodies to herpes simplex virus (HSV) in women seropositive for HSV Types 1 and 2

Antibodies to herpes simplex virus type 1 (HSV-1) and HSV-2 of the immunoglobulin G (IgG) and IgA isotypes were detected in the cervicovaginal secretions (CVS) of 77 HSV-1- and HSV-2-seropositive but clinically asymptomatic African women by type-specific enhanced chemiluminescence Western blotting (ECL-WB). Of the 77 subjects, 34 were HIV negative, shedding HSV-2 DNA in their genital secretions; 20 were HIV positive, shedding HSV-2 DNA; and 23 were HIV negative, not shedding HSV-2 DNA. HSV-specific IgG was detected in CVS of nearly 70% of the women studied. HSV-specific IgA was found in CVS of 50% of the women studied. The distribution of CVS HSV-specific antibodies to each HSV type was highly heterogeneous, with a slight predominance of detectable IgG to HSV-1 (59%) over IgG to HSV-2 (41%), whereas the frequency of detectable IgA to HSV-1 (39%) was similar to that of IgA to HSV-2 (36%). The presence of detectable HSV-specific antibodies was inversely associated with HSV-2 DNA genital asymptomatic shedding but was not affected by HIV seropositivity. In addition, 13 of 77 (17%) CVS samples showed neutralizing activity against HSV-2, as assessed by an HSV-2 in vitro infectivity reduction assay. Neutralizing activity in CVS was associated with the presence of IgG and/or IgA antibodies to HSV-1 and/or to HSV-2 by ECL-WB. Among women whose CVS showed HSV-2-neutralizing activity, the specific activity of HSV-specific neutralizing antibodies was substantially (fivefold) higher in HSV-2 DNA shedders than in nonshedders. In conclusion, HSV-specific antibodies are frequently detected in CVS of asymptomatic African women seropositive for HSV-1 and HSV-2. A subset of these women had functional neutralizing activity against HSV-2 in their CVS. The origin of these antibodies and their role in HSV-2 disease of the female genital tract remain to be determined.

Antibodies against human papillomavirus type 16 and 18 E6 and E7 proteins in cervicovaginal washings and serum of patients with cervical neoplasia

Serum antibodies against the E6 and E7 proteins of human papillomavirus (HPV) 16 and 18 are associated with cervical cancer. The aim of this study was to investigate the presence of local antibodies against HPV in cervicovaginal washings (CWs). In this study antibodies against the native HPV16 and HPV18 E6/E7 proteins were detectable in CWs (48%) and sera (29%) from patients with cervical cancer (n = 21) utilizing a sandwich protein enzyme-linked immunosorbent assay (ELISA). In paired CWs and sera from patients with cervical intraepithelial neoplasia (n = 38) and from healthy women (n = 22) no antibodies against these proteins were found. In 10 of 11 patients, the antibody response corresponded with the HPV type in the cervical smear and/or tumor tissue, which indicates the HPV type specificity of the assay. In 7 of 11 patients with antibody reactivity against HPV16 or HPV18 E6 and/or E7 proteins a higher level of antibody reactivity in the CWs than in the paired serum samples was found at similar inputs of total IgG. This suggests that the antibodies in the CWs against the investigated HPV proteins in these patients were locally produced.

Induction of specific immune responses in the genital tract of women after oral or rectal immunization and rectal boosting with Salmonella typhi Ty 21a vaccine

The purpose of this study was to determine the efficacy of intestinal tract immunization in the induction of specific antibodies in human female genital tract secretions. Live attenuated typhoid vaccine Ty 21a was administered to three groups of healthy female volunteers, who were not using hormonal contraceptives. Group 1 included 15 women vaccinated orally. Group 2 included seven of the same women, who were vaccinated rectally 6 months later. Group 3 included 11 volunteers, who were vaccinated rectally. Salmonella-specific antibodies of IgG and IgA were measured in vaginal lavage and cervical mucus after oral or rectal primary vaccination. Salmonella-specific antibodies measured 1 month after rectal booster vaccination demonstrated significant increases in vaginal fluids and cervical mucus and were dominated by IgA. These results indicate that specific antibodies in the human female genital tract induced by primary vaccination can be enhanced by subsequent rectal administration of vaccines.

Host pathogenesis in urinary tract infections

Urinary tract infections (UTIs) are the result of an interaction between bacterial virulence and host defense factors that compete to invade or protect the host, respectively. Research over the past 30 years has demonstrated that vaginal colonization with uropathogens precedes most UTIs. Receptivity of the vaginal mucosa for uropathogens is an essential initial step in vaginal mucosa colonization. When vaginal and buccal epithelial cells were collected from patients susceptible to reinfection and compared with such cells obtained from controls resistant to UTIs, the strains that caused cystitis adhered much more avidly to the epithelial cells from susceptible women. These genotypic traits for epithelial cell receptivity may be a major susceptibility factor in UTIs. The presence or absence of blood group determinants on the surface of uroepithelial cells may influence an individual's susceptibility to UTIs. The protective effect in women with the secretor phenotype may be due to fucosylated structures at the cell surface which decrease the availability of putative receptors for Escherichia coli. Susceptibility among women who do not secrete blood group antigens may be due to specific E. coli-binding glycolipids that are absent in women who secrete blood group antigens. Recent studies have shown that the vaginal fluid, which forms an interface between uropathogens and epithelial cells, also influences vaginal colonizations.

Epidemiologic and mucosal immunologic aspects of HPV infection and HPV-related cervical neoplasia in the lower female genital tract: a review

Human papillomavirus (HPV) infections are known to play an important role in the pathogenesis of cervical neoplasia. Considering the morbidity and mortality of cervical cancer, infection with HPV can be regarded as a worldwide problem, especially in developing countries. Currently, many studies focus on the development of both prophylactic and therapeutic HPV vaccines. Crucial for these vaccination protocols to be successful is that they will result in a long-lasting ability to generate an immune response that will eliminate the virus. HPV transmission and subsequent infection is a local event in the lower female genital tract and therefore the efficacy of vaccines against this locally transmitted infection can be best assessed by parameters of local immunity. In this review we describe both the epidemiology of HPV-related cervical neoplasia and the general aspects of mucosal immunity in the female genital tract while focusing on the local humoral immunity in HPV-related cervical neoplasia.

Predominate HIV1-specific IgG activity in various mucosal compartments of HIV1-infected individuals

Evaluating mucosal humoral immunity is important for understanding local immunity induced by HIV infection or vaccination and designing prophylactic strategies. To characterize the mucosal humoral immunity following HIV infection, the levels of immunoglobulins (Igs), antibodies (Abs), and HIV1-specific Ab activity were evaluated in cervicovaginal secretions (CVS), saliva, breast milk, and sera of HIV-infected individuals. HIV1-specific IgG activity was significantly higher than that of IgA in CVS, saliva, and breast milk. The highest HIV1-specific IgG activity was found in breast milk. The data suggest that anti-HIV1 Abs in CVS were most likely serum derived. However, HIV1-specific Abs in saliva and breast milk were mainly locally produced. The prevalence of HIV1-specific Abs in seropositive subjects was 97% for IgG and 95% for IgA in CVS, 100% for IgG and 80% for IgA in saliva, and 59% for IgG and 94% for IgA in breast milk. These data provide evidence for both a better understanding of the nature of humoral mucosal responses after HIV1 infection and the development of strategies to induce desirable functional mucosal immunity for preventing HIV transmission.

Evidence for a unique expression of CD4 on murine vaginal CD4+ cells

Mucosal cell-mediated immunity (CMI) by CD4+ T cells is postulated to be important for host defence against several vaginal pathogens. In addition to the recognized phenotypic distinctions of resident vaginal T lymphocytes, we recently provided evidence by fluorescence-activated cell sorter (FACS) that murine vaginal CD4+ T lymphocytes, are differentially recognized by two epitope-distinct anti-CD4 antibodies, suggesting that the CD4 protein on vaginal CD4+ cells is atypically expressed. In the present study, we confirm this by FACS and immunohistochemistry under non-denaturing conditions using two additional anti-CD4 antibodies. However, positive immunohistochemical staining of vaginal CD4+ cells under denaturing conditions revealed that the CD4 epitope in question is indeed present within the CD4 protein. Using reverse transcription polymerase chain reaction, amplification of CD3, T-cell receptor-beta (TCR-beta), and TCR-delta mRNA from lymph node and vaginal tissue, and CD4 mRNA from lymph node tissue was demonstrable. In contrast, amplification of CD4 mRNA from vaginal tissue, vaginal enriched lymphoid cells, or a purified (FACS-sorted) population of vaginal-specific CD4+ cells using two distinct primer sets was not demonstrable. Altogether, our results provide evidence that the CD4 protein on vaginal CD4+ T cells is conformationally distinct compared with its systemic counterpart, either as a result of a unique CD4 mRNA sequence or from a stable interaction of soluble CD4 with the surface of vaginal T cells.

IgG antibodies against human papillomavirus type 16 E7 proteins in cervicovaginal washing fluid from patients with cervical neoplasia

Little information is available about the cervicovaginal mucosal antibodies against human papillomavirus (HPV) proteins. In this study specific IgG antibodies against HPV 16 E7 protein were determined in paired samples of cervicovaginal washing fluid and serum from patients with cervical cancer (n = 22), cervical intraepithelial neoplasia (CIN) (n = 38), healthy individuals (n = 22), and serum from children (n = 41) by a radioactive immunoprecipitation assay (RIPA). HPV 16 E7 specific IgG antibodies were found in cervicovaginal washings (n = 8) and in sera (n = 8) of the patients with cervical cancer. About 60% of the patients with HPV 16 positive cervical cancer had HPV 16 E7 specific IgG antibodies. Titration studies showed that the IgG antibody reactivity in cervicovaginal washings was higher than in the paired serum samples of six patients with cervical cancer (P < 0.001). In the CIN group we found no IgG reactivity in the serum, but in five patients we found a low IgG reactivity in the cervicovaginal washings. No IgG reactivity was found in cervicovaginal washings and sera from healthy individuals and sera from children. HPV 16 E7 specific IgG antibodies seem to be locally produced in a number of patients with HPV 16 positive (pre)malignant cervical lesions. For more definitive evidence for the local production of these antibodies immunostaining should be performed to demonstrate the presence of specific anti-HPV 16 E7 IgG producing plasma cells in the cervical epithelium.

An ELISA method to measure total and specific human secretory IgA subclasses based on selective degradation by IgA1-protease

We have taken advantage of the property of IgA1-proteases to selectively cleave the human IgA1 subclass into Fabalpha and Fcalpha-J chain-secretory component (Fcalpha-J-SC) fragments in order to design a novel ELISA method for measuring the two secretory IgA (S-IgA) subclasses in secretions. The assay is based on the loss of detection of S-IgA1 by a combination of peroxidase-labelled antibodies to secretory component and Fab following IgA1-protease treatment. The specificity is that of the protease and the sensitivity of the detection is 5 ng/ml. Moreover, the use of purified S-IgA1 and S-IgA2 controls is not necessary. The assay has been successfully applied to the analysis of colostral S-IgA antibodies (Abs) to HIV-1-gp160 from HIV-1 positive women. The major subclass of colostral S-IgA antibodies to gp160 was found to be of the alpha1 isotype but the specific activity of anti-HIV-gp160 S-IgA2 was, however, higher than that of S-IgA1.

Roles of glycoproteins and oligosaccharides found in human vaginal fluid in bacterial adherence

Adherence of type 1-piliated Escherichia coli to carbohydrate structures of vaginal mucosa plays a major role in the pathogenesis of ascending urinary tract infections in women. Colonization of the vaginal introitus is influenced by interactions between pathogens, vaginal fluid, and vaginal epithelium. In this study, the type and amount of carbohydrates and glycoproteins present in vaginal fluid were determined. Free and protein-bound oligosaccharides in vaginal fluid specimens were analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and high-pressure liquid chromatography (HPLC). Two-dimensional electrophoretic separations of vaginal fluid glycoproteins were performed together with bacterial overlay assays. The results of FACE showed that the majority of the oligosaccharides are in the free state and the bound oligosaccharides are undetectable. HPLC analysis of free sugars revealed glucose as the major sugar (3.3 +/- 0.3 mM), and the concentrations of mannose and glucosamine were 0.065 +/- 0.04 and 0.02 +/- 0.001 mM, respectively. Radiolabeled E. coli bound three vaginal fluid glycoproteins with the following molecular masses and pIs: 82 kDa and pI 5.5, 55 kDa and pI 4.5, and 55 kDa and pI 6.5. The binding was inhibited by mannose and by deglycosylation of the proteins prior to the overlay assay. One of these putative receptors was identified to be the heavy chain of secretory IgA (S-IgA). These data suggest that the free mannose in the fluid is less than that required to affect E. coli-epithelial cell binding interactions and that S-IgA may bind E. coli in the vaginal introitus.

Immunoglobulins of the human amniotic fluid

PROBLEM

Except for the description of a secretory immunoglobulin (S-Ig) of a low size, no recent study has investigated the molecular status of antibodies in the human amniotic fluid.

METHOD

After separation with a high performance chromatography, we analyzed the different isotypes of amniotic Igs by immunoblotting and ELISA.

RESULTS

IgG is found to be the major isotype and to contain mother-derived tetanus antitoxins. IgA is much less abundant, whereas no IgM can be detected. IgA is monomeric, with a low level of secretory IgA and with various amounts of free secretory component (SC). The presence of a low level of SC-containing immunoglobulin of a low size is confirmed during the last trimester of pregnancy. This molecule contains no alpha chain but includes a Fabgamma fragment noncovalently associated with SC. IgG, IgA, and SC are detected in the fetal urine and, therefore, can reach the amniotic fluid by this route.

CONCLUSION

In addition to the predominant maternal IgG, the amniotic fluid contains different molecular forms of fetal immunoglobulins. Their function as an immune barrier against infection and against mother-derived autoantibodies is discussed.

Compartmentalization of the IgG immune response to HIV-1 in breast milk

OBJECTIVE

To evaluate the IgG immune response to HIV-1 in colostrum.

METHODS

Paired serum and colostrum were collected from 16 asymptomatic HIV-1-infected women. IgG to gp160 and to four peptides (gp41 immunodominant DI domain, gp41/Id; EDLKWA epitope of DIII domain, gp41/K; gp120 C-terminus, gp120/Ct; V3 loop, gp120/V3) were evaluated in all samples. Functional activity of purified IgG was assessed for the ability to block transcytosis of cell-associated HIV-1 through a tight monolayer of endometrial epithelial cell line HEC1.

RESULTS

IgG antibody to gp160 and to the four env-encoded synthetic peptides were detected in all specimens. The mean specific activity of IgG to gp41/K was 4.2 fold higher in colostrum than in paired serum. In contrast, mean specific activities of IgG to gp160 and gp41/Id were twofold higher in serum than in paired colostrum. Mean specific activities of IgG to gp120/V3 and to gp120/Ct were similar in systemic and milk compartments. Functional activity of IgG was evaluated in six paired serum and colostrum: in two women, serum IgG was 3.0 and 7.6 fold more efficient in blocking transcytosis than colostrum IgG; in one patient, colostrum IgG exhibited a 28 fold higher inhibitory capacity than serum IgG; in the remaining patients, serum and colostrum IgG demonstrated similar inhibitory activities against transcytosis of HIV.

CONCLUSION

These features are consistent with a compartmentalization of the humoral IgG immune response to HIV within the mammary gland. Some HIV-1 antigens are able to induce a strong humoral mucosal immune response which may be of relevance for the design of a mucosal vaccine against HIV-1.

Infectious human immunodeficiency virus can rapidly penetrate a tight human epithelial barrier by transcytosis in a process impaired by mucosal immunoglobulins

Mucosal surfaces are the main natural site of entry into the body for human immunodeficiency virus (HIV). Herein, an alternative mechanism for virus spread is described. The mechanism, which involves transcytosis of endosome-internalized HIV-particles, was generated by contact of HIV-infected cells with the apical surface of an epithelial cell line. Transcytosed viruses rapidly (in 20-30 min) access the serosal side of the epithelial barrier without infecting the epithelium itself. In turn, transcytosed HIV could infect host submucosal mononucleated target cells, and thus the infection could spread. An investigation was done to determine whether mucosal antibodies could block HIV transcytosis. Both secretory IgA (S-IgA) and IgG that were purified from colostrum from HIV-seropositive women impaired HIV transcytosis, irrespective of the level of the recombinant HIV envelope anti-gp160-specific activities in an ELISA. However, specific S-IgAs were more efficient than IgG. Therefore, mucosal-specific S-IgA to HIV-1 could be relevant to reducing infectivity of HIV-1 in corporeal fluids.

The specificity patterns of human immunoglobulin G antibodies in serum differ from those in autologous secretions

The specificity patterns of immunoglobulin G (IgG) antibodies to streptococcal antigens in serum and autologous secretions were compared in order to determine whether IgG found in human secretions is exclusively of serum origin or can also be locally produced irrespective of the systemic immune system. Surface antigens from a type 6 M-protein strain of Streptococcus pyogenes were extracted by cell wall digestion and subjected to sodium lauryl sulfate-polyacrylamide gel electrophoresis under reducing conditions. After being blotted onto nitrocellulose, the antigens were incubated with purified IgG from various body fluids: saliva, cervicovaginal secretions, seminal fluid, and colostrum. Binding was then revealed with labeled antibodies to human Fcgamma fragments. The antibody specificity patterns obtained by computer-assisted analysis were compared with those of paired sera. Major variations were observed between serum and secretions, as well as between different secretions from the same subject. These results are in favor of IgG-associated local immunity within different tissue compartments. This IgG response to mucosal antigens can complement that of secretory IgA in the defense against pathogens and should be taken into account during topical vaccinations.

Mucosal immunity in the female genital tract

Immunoglobulin (Ig)-producing cells in mucosal tissues represent quantitatively the most important humoral immune system of the body. All exocrine tissue sites contain immunocytes (B-cell blasts and plasma cells) that mainly synthesize dimers and larger polymers of IgA (collectively called pIgA) with incorporated J chain. Such pIgA is actively transported to external secretions as secretory IgA (SIgA) by the polymeric Ig receptor (pIgR), a transmembrane epithelial glycoprotein also called the secretory component (SC). The same transport mechanism includes pentameric IgM to generate SIgM. Although the most active SIgA system occurs in the gut, secretory immunity also operates in the female genital tract, with considerable pIgA production in the cervical mucosa and fallopian tubes. The origin of these local IgA immunocytes remains undefined. In mice, both lymphoid tissue in the large bowel (GALT) and nasopharynx (NALT) have been suggested as inductive sites for B cells homing to the urogenital tract. It is well established that integrin alpha 4 beta 7 is used by primed lymphoid cells to enter the intestinal lamina propria through interactions with mucosal addressin cell adhesion molecule (MAdCAM)-1 expressed on venule endothelium. However, alpha 4 beta 7 does not appear to be an important homing molecule in the airways, and the same might be true for the urogenital tract; this could explain that high levels of IgA antibodies occur in cervicovaginal secretions of mice after nasal immunization. The endometrium can likewise perform pIgR-mediated external translocation of pIgA that in this tissue appears to be mainly derived from serum, partly under hormonal regulation. In addition, paracellular diffusion of serum-derived and locally produced IgG through epithelia is an important part of humoral immunity in the female genital tract.

IgA immunity in HIV type 1-infected chimpanzees. II. Mucosal immunity

Vaginal wash fluids from chimpanzees cervically infected with HIV-1 and saliva from intravenously and cervically infected chimpanzees were analyzed for total IgA, IgA1, IgA2, IgG, and albumin concentrations and for reactivity against HIV-1. No overt abnormalities were detected in salivary immunoglobulin or albumin concentrations in either group of animals. Anti-HIV IgA and IgA subclass antibodies were demonstrated in saliva from five of six intravenously infected chimpanzees and in two of four cervically infected animals, with titers ranging from 1:5 to 1:20. HIV-specific IgG antibodies could be detected in saliva from half of the systemically infected group, the highest titer being 1:2560, whereas the highest anti-HIV IgG titer in the mucosally infected group was 1:20. Western blot analyses of the first saliva samples obtained after initial virus exposure revealed IgG, IgA, and IgA subclass antibodies directed at the env, gag, or pol gene products in both groups of chimpanzees. Examination of IgG, IgA, IgA1, and IgA2 concentrations in vaginal washes from cervically infected animals showed that IgG levels were highest, but IgA and IgA subclass reactivities against HIV-1 were more prominent than that of IgG. These results demonstrate that systemic infection of chimpanzees with HIV-1 elicits mucosal responses specific for HIV, and vaginal infection of chimpanzees induces a common mucosal immune response reminiscent of that in humans.

High-level ability of secretory IgA to block HIV type 1 transcytosis: contrasting secretory IgA and IgG responses to glycoprotein 160

The IgG and secretory IgA (S-IgA) responses to the HIV-1 envelope (gp160 antigen) were analyzed in the colostrum (Col) and in the cervicovaginal fluid (CVF) of HIV-l-infected women. We show IgG antibodies (Abs) to the recombinant gp160 to be predominant as compared with the corresponding S-IgA isotype. The low level of the S-IgA response cannot be related to a general disturbance of the mucosal-associated Iymphoid tissue (MALT) because the level of a current Ab to a caries-associated antigen from Streptococcus sobrinus was in the normal range in these secretions. The major subclass of IgA to gp160 was of the alpha1 isotype both in Col and in CVF. However, the specific activities of S-IgA1 and S-IgA2 were different when expressed as the ratio of the anti-gp160 related to total Ig of each subclass. Indeed, the specific activity of the S-IgA2 was predominant over S-IgA1 in the Col, whereas the reciprocal results were found in CVF, showing a subcompartmentalization of these secretions. The ability of S-IgA and IgG to block one of the pathways involved in the HIV-1 penetration across mucosa, i.e., transcytosis through epithelial cells, was evaluated using a functional in vitro assay. Both S-IgA and IgG Abs impaired virus transcytosis, irrespective of the level of antigp160 specific activities. However, specific S-IgA was more efficient than IgG. These features suggest that mucosal specific S-IgA to HIV-1 could be relevant in decreasing infectivity of HIV-1 in corporal fluids.

Use of cellular depletion analysis to examine circulation of immune effector function between the vagina and the periphery

Results from an animal model of vaginal candidiasis suggest that Candida-specific cell-mediated immunity in the systemic circulation does not mediate protection against vaginitis. The present study used cellular depletion analysis to examine the circulation of immune effector function between the vagina and the periphery. Results showed that anti-Thy-1.2 antibodies given intravenously to mice depleted Thy-1+ T lymphocytes in the systemic compartment but not in the vaginal mucosa, while the same antibodies injected intravaginally significantly reduced Thy-1+ T cells in both the vaginal and systemic compartments. These results support a lack or low level of circulation of immune effector function from the periphery to the vaginal mucosa.

Comparison of the oral, rectal, and vaginal immunization routes for induction of antibodies in rectal and genital tract secretions of women

To determine which mucosal immunization routes may be optimal for induction of antibodies in the rectum and female genital tract, groups of women were immunized a total of three times either orally, rectally, or vaginally with a cholera vaccine containing killed Vibrio cholerae cells and the recombinant cholera toxin B (CTB) subunit. Systemic and mucosal antibody responses were assessed at 2-week intervals by quantitation of CTB-specific antibodies in serum and in secretions collected directly from mucosal surfaces of the oral cavity, rectum, cervix, and vagina with absorbent wicks. The three immunization routes increased levels of specific immunoglobulin G (IgG) in serum and specific IgA in saliva to similar extents. Rectal immunization was superior to other routes for inducing high levels of specific IgA and IgG in rectal secretions but was least effective for generating antibodies in female genital tract secretions. Only vaginal immunization significantly increased both specific IgA and specific IgG in both the cervix and the vagina. In addition, local production of CTB-specific IgG in the genital tract could be demonstrated only in vaginally immunized women. Vaginal immunization did not generate antibodies in the rectum, however. Thus, generation of optimal immune responses to sexually transmitted organisms in both the rectal and the genital mucosae of women may require local immunization at both of these sites.

Comparative analysis of methods for collection and measurement of immunoglobulins in cervical and vaginal secretions of women

The purpose of this study was to systematically compare 3 collection methods, Sno-strips, wicks and cervical-vaginal lavage, for analysis of immunoglobulin concentrations in female genital secretions. In each of 8 women, absorbent wicks and Sno-strips were applied at 4 locations: the lateral wall of the vagina; the posterior vaginal fornix; the surface of the exocervix; and the endocervical canal. Cervical-vaginal lavage was then performed in 4 women with 5 ml PBS. Immunoglobulin and protein concentrations in lavage samples were generally over 100 times lower than in the secretions captured directly from mucosal surfaces with either Sno-strips or wicks. Capture of undiluted secretions with either wicks or Sno-strips allowed calculation of actual immunoglobulin concentrations at specific mucosal sites: for example, median IgA levels were consistently highest in the endocervix and lowest in the vagina. Such information may be crucial in evaluating the correlates of protective immunity against micro-organisms that infect or invade discrete regions of the genital mucosa.

Cervicovaginal synthesis of IgG antibodies to the immunodominant 175-199 domain of the surface glycoprotein gp46 of human T-cell leukemia virus type I

Paired sera, saliva and cervicovaginal secretions from 17 HTLV-I-infected women (19-75 yr) were tested for total IgA and IgG, for IgA and IgG to the immunodominant region gp46/175-Pro-199, for serum IgG to the neutralizing domains gp46/ 190-Pro-199 and gp46/190-Ser-199, or for tax-rex proviral HTLV-DNA. Serum antibodies to gp46/ 175-Pro-199 were detected more frequently in the IgG (13/17) than in the IgA (5/17) isotypes. The majority (8/12) of anti-gp46/175-Pro-199-positive sera reacted also to gp46/190-Pro-199 or to gp46/ 190-Ser-199, demonstrating their neutralizing properties. In saliva, antibodies to gp46/175-Pro-199 were not generally detected. In cervicovaginal secretions, IgG to gp46/175-Pro-199, but not IgA, were detected in 6/15 (40%) patients. The mean specific activity of IgG to gp46/175-Pro-199 showed a trend to be higher in cervicovaginal secretions (218 +/- 109) than in sera (14 +/- 4). Furthermore, in all patients with cervicovaginal IgG to gp46/175-Pro-199, the cervicogaginal/serum ratio (19 +/- 6) of anti-gp46 IgG specific activities were markedly above 1. HTLV-DNA was detected in 4/17 salivas, and in 3/15 cervicovaginal secretions, all from patients demonstrating cervicovaginal synthesis of IgG to gp46/175-Pro-199. In conclusion, IgG to gp46/175-Pro-199 in cervicovaginal secretions, when present, appear to be produced primarily locally because of local HTLV-I excretion. Since anti-gp46/175-Pro-199 antibodies usually support reactivities to neutralizing domains, their presence could be relevant for limiting HTLV-I transmission via cervicovaginal secretions.

Immunopathogenesis of recurrent vulvovaginal candidiasis

Recurrent vulvovaginal candidiasis (RVVC) is a prevalent opportunistic mucosal infection, caused predominantly by Candida albicans, which affects a significant number of otherwise healthy women of childbearing age. Since there are no known exogenous predisposing factors to explain the incidence of symptomatic vaginitis in most women with idiopathic RVVC, it has been postulated that these particular women suffer from an immunological abnormality that prediposes them to RVVC. Because of the increased incidence of mucosal candidiasis in individuals with depressed cell-mediated immunity (CMI), defects in CMI are viewed as a possible explanation for RVVC. In this review, we attempt to place into perspective the accumulated information regarding the immunopathogenesis of RVVC, as well as to provide new immunological perspectives and hypotheses regarding potential immunological deficiencies that may predispose to RVVC and potentially other mucosal infections by the same organism. The results of both clinical studies and studies in an animal model of experimental vaginitis suggest that systemic CMI may not be the predominant host defense mechanism against C. albicans vaginal infections. Rather, locally acquired mucosal immunity, distinct from that in the peripheral circulation, is now under consideration as an important host defense at the vaginal mucosa, as well as the notion that changes in local CMI mechanism(s) may predispose to RVVC.

Colonization in the rectum and uterine cervix with group B streptococci may induce specific antibody responses in cervical secretions of pregnant women

We have studied the relationships between genital or rectal carriage of group B streptococci (GBS) with the levels of systemic and mucosal antibodies to GBS in 200 women at about week 17 of pregnancy. Secretions from the uterine cervix were collected with absorbent cylindrical wicks for quantification of antibody levels with whole cell enzyme-linked immunosorbent assay. GBS were cultured from the cervix (with or without concomitant rectal colonization) of 13.5%, from the rectum (with or without concomitant cervical colonization) of 12%, and from both culture sites of 8.5% of the women. Serotypes Ia, II, and III were predominant. Compared with culture-negative women, the group of women colonized rectally had markedly elevated levels of both immunoglobulin A (IgA) and IgG antibodies to GBS in cervical secretions and also had a moderate but significant elevation of IgA antibodies in sera. Women colonized only in the cervix had increases of specific IgA and IgG antibodies in cervical secretions, but their serum antibody levels were not elevated. In cervical secretions, the increase in antibody levels in the groups of colonized women was most pronounced for the IgG isotype, indicating a mucosal immune response involving IgG as well as IgA. A close correlation was found among the levels of antibodies to each of the three GBS serotypes tested. Evidence for such cross-reacting antibodies to different serotypes of GBS, as well as to group A streptococci, was also obtained from absorption experiments. Altogether, our results show that undiluted secretions for antibody determination can be easily collected from the uterine cervix with absorbent wicks and demonstrate that colonization of GBS in the rectum and the uterine cervix may induce a systemic as well as a pronounced local immune response in the female genital tract. The findings may have implications for the development of a mucosal vaccine against GBS disease.