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Uterine cervical mucus contains an immunoglobulin binding factor (IgBF). It may play a role in preventing antibody production against sperm in the female reproductive tract. To elucidate the mechanism involved in the production of activated IgBF, we determined the effects of hormones on the expression of mRNAs of IgBF and of protein disulfide isomerase (PDI), activating enzyme, in uterine cervix by quantitative RT-PCR. The uterine cervices of female rats were excised at preovulatory, ovulatory, and postovulatory phases. The human uterine cervical adenocarcinoma cells (TCO-2) were cultured for 24 h in serum-free medium containing 17beta-estradiol or progesterone. Expression of IgBF and PDI mRNAs was significantly highest during the ovulatory phase. 17beta-estradiol stimulated the expression of both mRNAs in TCO-2; whereas progesterone was ineffective. In conclusion, estrogen regulates the production of IgBF by the endocervix and PDI in vivo, thereby increasing the level of activated IgBF in the female reproductive tract during the ovulatory phase, allowing sperm to enter the uterine cavity.

Objective: Immunoglobulin binding factor (IgBF) is known to bind immunoglobulin, to interact with anti-Fc gamma-III antibodies and to be present in the lower respiratory tract of normal healthy subjects. In this study, in order to clarify the role of IgBF in respiratory diseases, we investigated whether IgBF exists in the airway of patients with chronic airway diseases., Methodology: IgBF was measured in the sputum of 28 normal subjects and 59 patients with chronic airway diseases including 37 cases of chronic bronchitis, 18 bronchiectasis, and four diffuse panbronchiolitis by enzyme-linked immunosorbent assay., Results: Immunoglobulin binding factor concentration in the sputum of patients with chronic airway diseases (purulent sputum, 50.2 +/- 8.2 microg/mL; mucoid sputum, 88.6 +/- 12.8 microg/mL) was higher than that in induced sputum of normal subjects (6.3 +/- 5.5 microg/mL; P < 0.001). Immunoglobulin binding factor level in mucoid sputum was significantly higher than that in purulent sputum (P < 0.05). A significant inverse correlation was shown between the IgBF level and the elastase activity in sputum, and the concentration of IgBF purified from seminal plasma was decreased by treatment with neutrophil elastase, indicating that IgBF might be degraded by elastase. In the gel filtration chromatography of both types of sputum, IgBF was eluted in a region corresponding to a molecular weight of 27 kDa as a single peak. Western blot analysis with a monoclonal antibody to IgBF indicated that IgBF in both types of sputum had a molecular weight of 27 kDa under non-reducing conditions and of 16 kDa under reducing conditions., Conclusion: These results demonstrate that a high level of IgBF is present in the respiratory tract of patients with chronic airway diseases and may be related to the pathogenesis of these diseases.

Human seminal plasma contains a factor that binds human IgG, designated as immunoglobulin binding factor (IgBF). Under reducing condition IgBF interacts with anti-Leu-11b, a murine monoclonal antibody raised against human FcgammaRIII/CD16. IgBF shows no binding activity under non-reducing condition. Three components having IgBF activity were separated by HPLC and their amino acid sequences determined. The main IgBF showed structural identity to beta-microseminoprotein (beta-MSP), prostatic secretory protein of 94 amino acids (PSP94) and beta-inhibin. The slight variation in the reported sequences of these proteins has been attributed to analytical error. In the present study the molecular masses of main IgBF and beta-MSP/PSP94 were found to be identical by mass spectrometry. In addition, a large component of IgBF and a shorter beta-MSP consisting of 93 amino acids were identified. The binding of beta-MSP for human IgG and anti-Leu-11b antibody is demonstrable only under reducing condition, determined by Western blot analysis. The present data clearly show that IgBF is a family composed of at least three isoforms. One of the members is beta-MSP/PSP94. This family should be designated as IgBF.

Human seminal plasma and cervical mucus contains an immunoglobulin binding factor (IgBF) which interacts with IgG as monomers under reducing condition. It may play a role in preventing antibody production against allogeneic sperms in the female reproductive tract. However, since IgBF is secreted as a homodimer that does not bind IgG, in vivo activation systems should be investigated. GSH reduces the inactive native dimer to the active monomer. Protein disulfide isomerase (PDI), a molecular chaperone, alters the configuration of dimers to active monomers. 20S proteasomes produced by activated T cells which cleave the dimers in the presence of GSH to active fragments. All these activating systems are widely distributed as cellular enzymes in vivo. Also PDI mRNAs are expressed in uterine cervix, endometrium and fallopian tube. Since these enzymes are produced upon stimulation by the immune system, we hypothesize that immunocompetent cells interact with allogeneic sperms, leading to the local production of these enzymes that will activate IgBF.

Immunoglobulin binding factor (IgBF) produced in the prostate is a useful marker for the diagnosis of prostatic tumor. IgBF was localized in the majority of epithelial cells of benign prostatic hypertrophy by an immunohistochemical technique. Prostate specific antigen (PSA), a known marker for prostatic cancer, was localized to all epithelial cells. Double immunolabeling of IgBF and PSA using fluorescent methods revealed that all epithelial cells producing IgBF were also immunopositive for PSA and some cells were positive only for PSA. The present findings suggest that the prostatic glands consist of two types of epithelial cells, one producing both IgBF and PSA and the other producing PSA alone.

The presence of IgBF as a sperm-coating antigen was demonstrated by showing that anti-IgBF antibodies agglutinate and immobilize human sperm and by localizing IgBF on sperm surface by immunofluorescence staining. Several components interacting with sperm immobilizing antibodies, known to be involved in infertility, are sperm-coating antigens. Anti-IgBF antibody in vitro did not block the ability of human sperm to penetrate human zona pellucida and zona-free hamster egg. Anti-IgBF activity of sera obtained from infertile women did not correlate with the titers of anti-sperm antibodies measured by the sperm immobilization test. IgBF is a sperm-coating antigen and may play a role in suppressing antibody production against alloantigenic sperm in the female reproductive tract.

Immunoglobulin binding factor (IgBF), which is abundant in human seminal plasma, is known to bind immunoglobulin, interact with anti-Fc gamma RIII antibodies, and block pokeweed mitogen (PWM)-stimulated lymphocyte blastogenesis. In this study, we investigated whether IgBF is present in the lower respiratory tract, whose secretions come into contact with the external environment. For this, IgBF was measured in brochoalveolar lavage fluid (BALF) from 42 healthy normal subjects (23 nonsmokers and 19 smokers) by enzyme-linked immunosorbent assay (ELISA). IgBF was detected in BALF from these normal subjects, and its level was significantly higher in BALF from smokers (127.2 +/- 98.7 ng/ml versus 23.3 +/- 20.7 ng/ml). On gel filtration chromatography of BALF, IgBF was eluted in a region corresponding to a molecular weight of 27 kD. Western blot testing with a monoclonal antibody to IgBF indicated that IgBF in BALF had a molecular weight of 27 kD under nonreducing conditions and of 16 kD under reducing conditions. Thus, the migration pattern of IgBF in BALF corresponded to that of IgBF in seminal plasma. IgBF immunoreactivity was detected histochemically in mucus glands and goblet cells in the lower respiratory tract. These results demonstrate that IgBF is present in the lower respiratory tract, and that smoking may cause its increased production in this region.

Immunoglobulin binding factor (IgBF) found in human seminal plasma may be involved in suppressing antibody production against sperm in the female and male genital tracts. In the present study an enzyme-linked immunosorbent assay (ELISA) for IgBF was developed using monoclonal anti-IgBF antibodies. The sensitivity of the method was 20 pg/ml. The method was used to quantify IgBF in sera from women. In addition high levels of IgBF was found in cervical mucus of the uterus and in bronchial washings. The present results suggest that IgBF is found in tissues that are exposed to the external environment and may be a component of the local immunity system.

Human seminal plasma contains an immunoglobulin gamma binding factor (IgBF) with an estimated molecular weight of 16 kD under reducing condition. IgBF was detected only in the prostate, including benign prostatic hypertrophy (BPH) and neoplasm. The present study was performed to determine whether IgBF is a useful prostatic marker. Serum IgBF levels were measured in patients with prostatic tumors and in control patients without tumor by radioimmunoassay. Serum prostatic-specific antigen (PSA), the standard prostatic marker, was also determined. Serum IgBF levels in patients with prostate cancer were significantly higher than those in age-matched controls (P < 0.05). Also, patients with BPH tended to have elevated IgBF levels than the controls, although the values were not statistically significant. In control patients, serum IgBF levels increased with advancing age. There was no correlation between serum levels of IgBF and PSA in patients with prostate cancer. Using cut-off level at 28.5 ng/ml (2 S.D. above the mean IgBF level of age-matched control), the sensitivities were 41.2% (7/17) for prostate cancer, 23.1% (6/26) for BPH, and 5.6% (1/18) for control patients. In conclusion, serum IgBF is a useful marker in the diagnosis of patients with prostatic tumor, and in evaluating the course of treatment.

Human seminal plasma contains a component that binds immunoglobulins (Ig). The Ig binding factor was purified by ammonium sulphate precipitation, preparative isoelectrofocusing and gel filtration chromatography and found to bind strongly human IgGl and mouse IgM. This seminal plasma component may possess immunosuppressive activity and may modulate the activities of the immunosurveillance system of the reproductive tract.

Human seminal plasma contains a protein with an estimated molecular weight of 16 kd that binds serum immunoglobulin gamma (IgG) and is named IgG binding factor (IgBF). Purified IgBF specifically suppressed pokeweed mitogen-induced lymphocyte blastogenesis, having little or no effect on lymphocyte blastogenesis stimulated with phytohemagglutinin or Concanavalin A; antibody-dependent cell-mediated cytotoxicity; natural killer cell activity; or complement-dependent cytotoxicity of antibodies against sperm. It would appear that IgBF may suppress activation of B cells in the male and female genital tract.

To determine the source of the immunoglobulin binding factor (IBF) in seminal plasma, extracts of testis and accessory male sex organs were prepared and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot. The detection reagents used were human and mouse serum Ig, monoclonal anti-Leu 11b antibodies, and polyclonal rabbit anti-IBF antibodies. Of the tissues examined, only the prostate, including benign hypertrophy and adenocarcinoma, contained IBF. These findings suggest that IBF is a secretory product of the prostate.

Human seminal plasma, testis, seminal vesicle, epididymis, and prostate contain a component with an estimated Mr of 20 kD that binds human immunoglobulin-Fc. The factor did not bind goat-IgG-Fc, immunoglobulins of human, rat, mouse, goat, horse, or rabbit sera and did not interact with antibodies raised against Fc gamma receptors. The present findings show that this Fc binding factor in seminal plasma is a secretory product of the testis and accessory sex organs. It binds human Ig-Fc but does not meet the criteria of an Fc receptor. Additional IgG-Fc binding proteins with estimated Mr of 90, 88, and 86 kD were detected in the prostate, testis, and seminal vesicle, respectively.

The amino acid sequence of the N-terminus of the immunoglobulin binding factor of human seminal plasma was determined. The initial 30 amino acids showed complete identity with that of prostatic secretory protein, beta-microseminoprotein and beta-inhibin. In conclusion, these proteins are probably a single entity.