Ultrastructural studies of human lymphoid cells. mu and J chain expression as a function of B cell differentiation.

J chain expression was examined as a function of the stage in differentiation along the B cell axis in humans. Intracellular distribution of J and mu chains in leukemic HLA-DR+ null and pre-B cells, and in normal B cells stimulated with pokeweed mitogen (PWM) was determined by immunoelectron microscopy and radioimmunoassay (RIA). J chain was detected in leukemic null and pre-B cells on free and membrane-bound ribosomes in the cytoplasm, or on perinuclear cisternae. Mu chain was found on free ribosomes and ribosomal clusters in leukemic pre-B cells but was absent in the leukemic null cells. In pre-B cell lines, mu chain was seen within rough endoplasmic reticulum (RER) and the Golgi apparatus whereas J chain was not detected in these organelles. However, both mu and J chain were detected in RER and the Golgi apparatus of immature and mature plasma cells induced by PWM stimulation of normal peripheral blood lymphocytes. Low levels of J chain were also detected by RIA in lysates of leukemic null and pre-B cells. Most of the intracellular J chain became detectable after reduction and alkylation of cell lysates, and free J chain was not found in the culture supernatants. The amount of intracellular and secreted immunoglobulin-bound J chain increased dramatically after PWM stimulation of peripheral blood lymphocytes. The majority of J chain-positive cells seen over an 8 d culture interval were lymphocytes and lymphoblasts, while mu chain was found primarily in plasma cells. These results suggest that J chain expression precedes mu chain synthesis during B cell differentiation and that a combination of the two chains for secretion is not initiated until the onset of plasma cells maturation.

Familial IgA nephropathy in southeastern Kentucky.

BACKGROUND: Two decades ago, pedigrees of patients with IgA nephropathy (IgAN) from Pike County, KY, USA, provided evidence for a role of genetic factors in the pathogenesis of this disorder. Subsequently additional pedigrees were described for several communities from northern Italy. Recently, we found another cluster of patients in the Clay County, KY area, about 100 miles southwest of Pike County. AIM: The purpose of this study was to evaluate and expand the pedigrees of patients with IgAN from Clay County, KY to provide additional insight into the mechanisms of inheritance of IgAN and assess the possible influence of a founder effect on the prevalence of IgAN in the region. METHOD: Since 1980, most patients with IgAN and their relatives in eastern KY have provided personal genealogic data. These data were used to construct pedigrees that included the patients born in Clay County. Nine of 11 patients with IgAN born in Clay County, KY, USA were members of 1 or more of 5 pedigrees, each with 3 - 11 patients with IgAN. CONCLUSION: Our findings suggest the possibility of a low-penetrance ancestral mutation in the IgAN kindreds from Clay County.

Role of aberrant glycosylation of IgA1 molecules in the pathogenesis of IgA nephropathy.

Studies of the properties of immune complexes (IC) in the circulation, urine, and mesangium of IgA nephropathy (IgAN) patients have provided data relevant to the pathogenesis of this disease. IC contain predominantly polymeric IgA1 molecules which are deficient in galactose (Gal) residues on O-linked glycan chains in the hinge region (HR) of their heavy (H) chains. As a result of this aberrancy, a novel antigenic determinant(s) involving N-acetylgalactosamine (GalNAc) and perhaps sialic acid (SA) of O-linked glycans is generated and recognized by naturally occurring GalNAc-specific antibodies. Thus, IC in IgAN consist of Gal-deficient IgA1 molecules as an antigen, and GalNAc-specific IgG and/or IgA1 as an antibody. IgG antibodies to Gal-deficient IgA1 are probably induced by cross-reactive microbial antigens; they are present at variable levels not only in humans with or without IgAN but also in many phylogenetically diverse vertebrate species. Incubation of human mesangial cells with IC from sera of IgAN patients indicated that stimulation of cellular proliferative activity was restricted to the large (>800 kDa) complexes. These findings suggest that experimental approaches that prevent the formation of large Gal-deficient IgA1-IgG IC may be applied ultimately in an immunologically mediated therapy.

Characterization of poliovirus replicons encoding carcinoembryonic antigen.

Recombinant vaccines hold great promise for the prevention and therapy of infections diseases and cancer. We have explored the use of poliovirus as a recombinant vector to deliver genes into cells for the purpose of vaccination. For our studies, we have chosen to express the gene-encoding carcinoembryonic antigen (CEA) using a novel poliovirus vector. We have constructed a recombinant CEA-poliovirus replicon in which the CEA gene was substituted for the poliovirus capsid gene. Following in vitro transcription, the RNA was transfected into cells to demonstrate CEA expression. We found that a genome in which the region encoding the signal sequence of the CEA protein (amino acids 1-34) was removed was replication competent (i.e., referred to as a replicon). We encapsidated the CEA-poliovirus replicon by transfecting this RNA into cells previously infected with a recombinant vaccinia virus (VV-P1) which expresses the poliovirus capsid protein (P1). Serial passage in the presence of VV-P1 resulted in the generation of stocks of these encapsidated replicons. Infection of cells with the encapsidated replicon containing the CEA-poliovirus genome resulted in expression of the CEA protein. To test immunogenicity, mice susceptible to poliovirus were given three doses of the encapsidated replicons via the i.m. route. By the third administration, a CEA-specific antibody response was detected. Potential future use of the poliovirus replicon system as both a parenteral and oral vaccine vector is discussed.

Chemokine-adjuvanted electroporated DNA vaccine induces substantial protection from simian immunodeficiency virus vaginal challenge.

There have been encouraging results for the development of an effective HIV vaccine. However, many questions remain regarding the quality of immune responses and the role of mucosal antibodies. We addressed some of these issues by using a simian immunodeficiency virus (SIV) DNA vaccine adjuvanted with plasmid-expressed mucosal chemokines combined with an intravaginal SIV challenge in rhesus macaque (RhM) model. We previously reported on the ability of CCR9 and CCR10 ligand (L) adjuvants to enhance mucosal and systemic IgA and IgG responses in small animals. In this study, RhMs were intramuscularly immunized five times with either DNA or DNA plus chemokine adjuvant delivered by electroporation followed by challenge with SIVsmE660. Sixty-eight percent of all vaccinated animals (P<0.01) remained either uninfected or had aborted infection compared with only 14% in the vaccine naïve group. The highest protection was observed in the CCR10L chemokines group, where six of nine animals had aborted infection and two remained uninfected, leading to 89% protection (P<0.001). The induction of mucosal SIV-specific antibodies and neutralization titers correlated with trends in protection. These results indicate the need to further investigate the contribution of chemokine adjuvants to modulate immune responses and the role of mucosal antibodies in SIV/HIV protection.

Human milk peroxidase is derived from milk leukocytes.

Peroxidase enzymes present in human colostrum, saliva, polymorphonuclear leukocytes, and bovine milk were compared with respect to their molecular exclusion chromatographic behavior and immunological cross-reactivity. Human milk peroxidase gave an elution profile similar to myeloperoxidase derived from blood polymorphonuclear leukocytes. Human salivary peroxidase reacted with an antibody directed against bovine lactoperoxidase, but with the same antibody preparation no reaction was detected either with human milk peroxidase or leukocyte myeloperoxidase. We conclude that the peroxidase enzyme in human milk is different from the human salivary and the bovine enzymes and is probably derived from milk leukocytes.

Biodegradable microspheres: vaccine delivery system for oral immunization.

The potential of biocompatible and biodegradable microspheres as a controlled release oral vaccine delivery system has been examined. Orally-administered 1-10 micron microspheres composed of poly (DL-lactide-co-glycolide) were specifically taken up into the Peyer's patch lymphoid tissue of the gut, where those greater than or equal to 5 micron remained for up to 35 days. Microspheres less than 5 micron disseminated within macrophages to the mesenteric lymph nodes and spleen. In contrast to soluble staphylococcal enterotoxin B toxoid, oral immunization with enterotoxoid in microspheres induced circulating toxin-specific antibodies and a concurrent secretory IgA anti-toxin response in saliva and gut fluid.

Recombinant viruses as vectors for mucosal immunity.

The development and characterization of viral based vaccine vectors is extremely active research field. Much of this work has been facilitated by developments in molecular biology that allow work with large plasmid-based vectors, as well as the use of PCR. Several different vector systems are now available using RNA viruses and DNA viruses. Each vector system has its own strengths and weaknesses. Due to the differences and diversity between the viruses used as vectors, it is doubtful that a single system will be useful for all desired vaccines. However, the further development of existing, as well as potentially new systems, will provide a repertoire for vaccinologists to design the recombinant vaccine which will generate an optimal humoral and immune response for protection against infection or disease caused by pathogens that infect via mucosal surfaces.

Immune responses to influenza virus in orally and systemically immunized mice.

In our studies on the induction of an immune response by oral immunization, we have explored the potential of a novel approach for antigen delivery by microencapsulation. This procedure preserved the immunogenicity of the influenza virus introduced by either systemic or oral routes. Furthermore, the levels of specific antibodies in serum and in saliva were enhanced and lasted longer (up to 4 months) in animals immunized with of antigens in microencapsulated form than in animals immunized with equal doses of free suspension. Preliminary challenge experiments showed a correlation between levels of antibodies and protection. All mice systemically immunized were protected against the virus, while mice orally immunized with lower doses of microencapsulated antigen had better survival rates than those immunized with higher doses. Additional experiments suggested that low doses of immunogen were able to generate better protective immunity than high doses, which may instead be tolerogenic. Further experiments with a well characterized microencapsulated antigen (size of microcapsules, time of release of antigen, as well as its dose and form) will be necessary to establish conditions for optimal immunization protocols applicable for the oral or systemic routes.

Biosynthesis of J-chain in human lymphoid cells producing immunoglobulins of various isotypes.

The relationship between synthesis, secretion, and subcellular localization of J-chain, IgM, IgA, and IgG was investigated in cultures of PWM-stimulated human PBL and in lymphoblastoid cell lines. Cells were examined for surface, cytoplasmic, and secreted immunoglobulins (Igs) and J-chain by immunofluorescence and radioimmunoassay (RIA). By these techniques, J-chain was detected in cells that produce polymeric or monomeric Igs. In PWM-stimulated PBL the synthesis of J-chain paralleled the production of Igs. In both PWM-stimulated (for 2 days) and unstimulated PBL, equal proportions of free and disulfide-linked J-chain were found. Increased amounts of intracellular J-chain were produced at later stages in PWM-stimulated PBL and J-chain occurred mostly in a free form. In tissue culture fluids, J-chain was not secreted in a free form but was always disulfide-linked to polymeric Igs. In lymphoblastoid cell lines, J-chain was present in a disulfide-linked form in IgM and IGA producers, but in IgG cells and in an IgM cell line (DAUDI) that did not secrete IgM but expressed it on the cell membrane, intracellular J-chain was present in free form. Although various proportions of polymeric and monomeric IgA were seen in culture fluids from IgA-secreting cell lines, intracellular IgA occurred mostly in a monomeric form. Further studies revealed that the ability to produce polymers was not equally distributed among all cells and might vary according to their content of J-chain and stage of maturation. Subcellular fractionation and subsequent analyses for J-chain and Ig in PWM-stimulated PBL and in IgM or IgG-producing cell lines revealed that these proteins were associated with fractions that contained ribosomes, cell sap, and low molecular weight RNA. In lysates of IgG and J-chain producing cells grown in the presence of 3H-labeled amino acids, intracellular J-chain was not disulfide-linked to IgG.

Interactions of cell-surface galactosyltransferase with immunoglobulins.

Detection of the activity of beta-1,4-galactosyltransferase (beta-1,4-GT) in suspensions of viable mouse hepatocytes, the human hepatoma cell line Hep G2, the human colonic adenocarcinoma cell line HT-29, the monocyte-like cell line U937, and human splenic B and T lymphocytes suggested the presence of beta-1,4-GT, in an enzymatically active form, on plasma membranes. The presence of beta-1,4-GT on cell surfaces was also indicated from the effect of trypsinization of live cells, which significantly reduced cell surface beta-1,4-GT activity, but did not affect the activity associated with cytoplasmic membranes. Furthermore, the presence of beta-1,4-GT on the cell surface was demonstrated by indirect immunofluorescence staining of cells with anti-beta-1,4-GT antibody. The detection of radioactivity in immunoglobulins (Ig) and their component chains after incubation with suspensions of intact cells in the presence of Mn2+ and UDP-[3H]-galactose, indicated that Ig molecules were galactosylated. In the absence of UDP-[3H]-galactose, beta-1,4-GT on cell surfaces, or immobilized on Sepharose-4B, formed stable complexes with galactose acceptors, including Ig. The efficiency of binding decreased in the order: J chain > alpha chain > mu chain > polymeric IgA2 > monomeric/polymeric IgA1 > IgM > IgG. Thus, beta-1,4-GT could act as a cell-surface receptor for Ig through a cation-dependent, lectin-like association of the beta-1,4-GT with the carbohydrate moieties of the Ig. This was confirmed by indirect surface immunofluorescence and radiolabeled ligand binding assays. The binding was inhibitable by EDTA, alpha-lactalbumin (in the presence of glucose), GlcNAc, or uridine 3',5'dialdehyde. At 37 degrees C, the apparent affinity constants and association rate constants of interaction between cell surface beta-1,4-GT on glutaraldehyde-fixed HT-29 and U937 cells and alpha 2 chain or monomeric IgA1 were in the range from 7.1 x 10(7) to 4.6 x 10(8) M-1 and from 1 x 10(5) to 3 x 10(6) M-1 s-1, respectively. The dissociation rate constants and half time of dissociation calculated from these data were in the range from 2.1 x 10(-2) to 5.0 x 10(-4) s-1 and from 33 to 1380 s, respectively. The number of alpha 2 or IgA1 molecules bound per HT-29 and U937 cell were in the range from 1.9 x 10(5) to 1.3 x 10(6). The binding of IgA by the cell surface beta-1,4-GT was not associated with internalization or the catabolic degradation of the ligand.

A novel two colour ELISPOT assay. I. Simultaneous detection of distinct types of antibody-secreting cells.

A novel assay system has been developed which is based on the ELISPOT methodology and employs a combination of two immunoenzyme visualization systems yielding distinct colour products. This variation permits the simultaneous enumeration of two different types of cell secreting antigenically distinct products. Optimal conditions for the concurrent detection of human mononuclear cells secreting IgG or IgA antibodies are described.

Heterogeneity of binding of monoclonal IgA to staphylococcal protein A is related to the IgA polymerization state.

The human IgA2-lambda myeloma protein Fel consists of covalent dimers and monomers which are partially self-associated. Affinity chromatography of this protein on staphylococcal protein A-Sepharose revealed that approximately 8% of the protein was retained and eluted by acid buffer. Although retained protein Fel was highly aggregated, in the presence of dissociating agents mostly monomeric form was found. Affinity rechromatography and electrophoresis of both fractions from affinity chromatography revealed that the retained fraction possessed substantially higher affinity for SpA than did the nonretained one. This could be due to the multivalency of protein Fel aggregates.

Mucosal immunity in the female reproductive tract: correlation of immunoglobulins, cytokines, and reproductive hormones in human cervical mucus around the time of ovulation.

Mucosal surfaces serve as the portal of entry for many viral, bacterial, and parasitic infections. Understanding the immunity at mucosal membranes is essential to enhancing protection and decreasing infections. To evaluate the humoral and cellular immunity in the female reproductive tract, 15 reproductive-age women with a history of regular, cyclic monthly menses were recruited for this study. The presence of immunoglobulins and cytokines in cervical mucus was correlated with the production of reproductive hormones in sera. Cervical mucus specimens were collected at each daily visit beginning on cycle day 8 and continuing for 5 days postovulation. Volunteers were monitored by daily urinary LH testing coupled with transvaginal ultrasonography to ascertain follicular collapse. The cervix was washed in sterile saline before aspirating the cervical mucus from the cervical canal. Collection volumes ranged between 50 and 800 microl and were considered to represent the total mucus produced. Estradiol displayed the characteristic biphasic pattern with a peak before ovulation and in the luteal phase. Both IgG (30 mg/dl) and IgA (15 mg/dl) had a biphasic pattern with peak immunoglobulin levels detected 1 day before the estradiol peak and increasing again just after ovulation. Peak interleukin 10 (40 pg/ml) levels corresponded precisely with estradiol peak levels just before ovulation. Peak interleukin 1beta (1.3 ng/ml) levels occurred approximately 1 day before the estradiol peak. No apparent pattern in interleukin 6 (150 pg/ml) could be ascertained. Our data suggest a correlation between the IgG and IgA immunoglobulin levels, interleukin 1beta and interleukin 10, in the female reproductive tract and estradiol levels in the circulation. The increase in immunoglobulins and cytokines occurs approximately 1 day before the peak estradiol production before ovulation. These data suggest a role for cytokines and hormones in the regulation of reproductive tract immunity.

New approaches for mucosal vaccines for AIDS: encapsidation and serial passages of poliovirus replicons that express HIV-1 proteins on infection.

It is apparent that a safe and effective HIV vaccine is an important component in the development of rational approaches for the control and prevention of HIV transmission. Given the fact that the virus most often encounters a mucosal surface during sexual transmission, a vaccine designed to stimulate both the systemic and mucosal immune systems is essential. Poliovirus is attractive as a delivery system because of several biological features inherent to the virus. First, the pathogenesis of the virus has been well studied, and important features have been identified. The virus is naturally transmitted by a fecal-oral route and is stable in the harsh conditions of the gastrointestinal tract. Second, previous studies using attenuated vaccine strains of poliovirus showed that a long-lasting systemic and mucosal immunity is generated after administration of the vaccines. Studies have demonstrated the presence of circulating T cells that proliferate to whole inactive poliovirus or peptides corresponding to amino acids of the VP1 proteins in previously immunized individuals. These results established that immunization with poliovirus stimulates both the humoral and cell-mediated components of the immune system. Third, the attenuated strains of poliovirus are safe for humans and are given to infants as early as 6 months of age. The incorporation of foreign genes into the attenuated strains would be an attractive feature that should pose no more of a health risk than that associated with administration of the attenuated vaccines. Finally, studies from this laboratory, as well as others, have established the feasibility of incorporating foreign genes into the poliovirus cDNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the expression and immunogenicity of poliovirus replicons that encode simian immunodeficiency virus SIVmac239 Gag or envelope SU proteins.

The effectiveness of the poliovirus vaccines to induce both systemic and mucosal immunity has prompted the development of this virus as a vector in which to express foreign proteins. Our laboratory has previously reported on the construction and characterization of poliovirus genomes that encode HIV-1 proteins (Porter DC, et al.: J Virol 1996;70:2643-2649). To develop this system further, we have constructed poliovirus genomes, referred to as replicons, which encode the SIVmac239 Gag or Env SU in place of the poliovirus capsid gene (P1). Since the replicons do not encode capsid proteins, they are encapsidated into poliovirus by passage with a recombinant vaccinia virus, VVP1, which provides the poliovirus capsid proteins in trans. Using this system, we have derived stocks of the encapsidated replicons which encode the SIVmac239 or Env SU protein. Infection of cells with the replicon that encodes SIVmac239 Gag resulted in the expression of a 55-kDa protein that was released from the infected cells. Analysis of the sedimentation of the released proteins by sucrose density gradient centrifugation revealed that the protein was released from the cell in the form of a virus-like particle. Infection of cells with the replicons encoding the SIVmac239 Env SU resulted in the expression of a 63-kDa protein, corresponding to the molecular mass predicted for the nonglycosylated SIVmac239 SU protein. A second protein with a molecular mass greater than 160 kDa was also immunoprecipitated. After enzymatic deglycosylation, this protein migrated at a molecular mass consistent with that for an Env SU dimer. Analysis of the medium from cells infected with the replicon encoding SIVmac239 Env SU revealed the presence of a protein of molecular mass 85-90 kDa, possibly representing a fragment of the SIVmac239 or Env SU protein. To determine the immunogenicity of the replicons encoding SIVmac239 Gag or Env SU, transgenic mice that express the human receptor for poliovirus, and are thus susceptible to poliovirus, were immunized via the intramuscular route. A serum antibody response to SIV envelope was detected following booster immunization, establishing that the encapsidated replicon was immunogenic. Finally, we demonstrate that the replicons have the capacity to infect peripheral blood mononuclear monocytes/macrophages, suggesting that this cell is a possible target for in vivo infection. The results of our studies, then, lend further support for the development and application of recombinant poliovirus replicons in a vaccine strategy.

Induction of immune responses to SIV antigens by mucosally administered vaccines.

In an attempt to develop an immunization strategy to induce mucosal and circulatory antibodies against SIV antigens, we have investigated the potential of attenuated recombinant vaccinia virus to deliver SIV antigens (gp160 of SIVmac239) to mucosal surfaces of mice. After systemic or mucosal (intragastric, intranasal, or intrarectal) immunization with vaccinia virus-SIV Env recombinants the immune responses against the envelope glycoprotein of SIV, as well as against vaccinia virus antigens, were assessed by ELISA of serum, saliva, and intestinal and vaginal secretions. All immunization routes induced specific antibody titers against gp160 in both serum and external secretions. Recall responses against SIV were found to be acquired after administration of SIVmac239 Env and Gag antigens in a virus-like particle (VLP) form by the same mucosal routes as those used for the priming with recombinant vaccinia virus. The results obtained demonstrate the potential of vaccinia virus recombinants to elicit a primary immune response at mucosal surfaces, which could be enhanced by delivering the same antigen in the form of VLPs.

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.

Biodegradable block copolymers for delivery of proteins and water-insoluble drugs.

Release of several drugs from new ABA-type biodegradable thermal gels, ReGel, including proteins and conventional molecules, are presented. These are biodegradable, biocompatible polymers that demonstrate reverse thermal gelation properties. Organic solvents are not used in the synthesis, purification, or formulation of these polymers. The unique characteristics of ReGel hinge on the following two key properties: (1) ReGel is a water soluble, biodegradable polymer at temperatures below the gel transition temperature; (2) ReGel forms a water-insoluble gel once injected. This is consistent with a hydrophobically bonded gel state where all interactions are physical, with no covalent crosslinking. An increase in viscosity of approximately 4 orders of magnitude accompanies the sol--gel transition. The gel forms a controlled release drug depot with delivery times ranging from 1 to 6 weeks. ReGel's inherent ability to solubilize (400 to >2000-fold) and stabilize poorly soluble and sensitive drugs, including proteins is a substantial benefit. The gel provided excellent control of the release of paclitaxel for approximately 50 days. Direct intratumoral injection of ReGel/paclitaxel (OncoGel) results in a slow clearance of paclitaxel from the injection site with minimal distribution into any organ. Efficacies equivalent to maximum tolerated systemic dosing were observed at OncoGel doses that were 10-fold lower. Data on protein release (pGH, G-CSF, insulin, rHbsAg) and polymer biocompatibility are discussed.

A polarized human endometrial cell line that binds and transports polymeric IgA.

We have demonstrated that a human endometrial cell line, HEC-1, maintains a transepithelial electrical resistance, directionally transports fluids across the cell monolayer, and releases enveloped viruses at distinct plasma membrane domains: influenza virus is released at the apical surfaces and vesicular stomatitis virus (VSV) at the basolateral surfaces. In addition, we have examined the expression of domain-specific endogenous proteins, including the polyimmunoglobulin receptor. Multiple endogenous polypeptides were found to be secreted into the culture medium at basolateral surfaces, whereas no secretion of specific polypeptides was observed from apical cell surfaces. Distinct patterns of endogenous proteins were also observed on apical and basolateral cell surfaces, with a much more complex polypeptide pattern on the basolateral membranes. Using surface biotinylation and immunofluorescence, the polyimmunoglobulin receptor was found to be expressed on the basolateral surface of HEC-1 monolayers. The specific binding of poly-immunoglobulin A (pIgA) was found to occur on the basolateral surface, and was followed by transcytosis to the apical surface and release into the apical medium. The observed characteristics indicate that the endometrium-derived HEC-1 epithelial cell line can be employed as a model for studies of protein transport in polarized epithelial cells of human endometrial tissues, as well as for studies of the interaction of microorganisms with epithelial cells in the genital tract.