IFN-α with dasatinib broadens the immune repertoire in patients with chronic-phase chronic myeloid leukemia.

In chronic myeloid leukemia (CML), combination therapies with tyrosine kinase inhibitors (TKIs) aim to improve the achievement of deep molecular remission that would allow therapy discontinuation. IFN-α is one promising candidate, as it has long-lasting effects on both malignant and immune cells. In connection with a multicenter clinical trial combining dasatinib with IFN-α in 40 patients with chronic-phase CML (NordCML007, NCT01725204), we performed immune monitoring with single-cell RNA and T cell receptor (TCR) sequencing (n = 4, 12 samples), bulk TCRß sequencing (n = 13, 26 samples), flow cytometry (n = 40, 106 samples), cytokine analyses (n = 17, 80 samples), and ex vivo functional studies (n = 39, 80 samples). Dasatinib drove the immune repertoire toward terminally differentiated NK and CD8+ T cells with dampened functional capabilities. Patients with dasatinib-associated pleural effusions had increased numbers of CD8+ recently activated effector memory T (Temra) cells. In vitro, dasatinib prevented CD3-induced cell death by blocking TCR signaling. The addition of IFN-α reversed the terminally differentiated phenotypes and increased the number of costimulatory intercellular interactions and the number of unique putative epitope-specific TCR clusters. In vitro IFN-α had costimulatory effects on TCR signaling. Our work supports the combination of IFN-α with TKI therapy, as IFN-α broadens the immune repertoire and restores immunological function.

Long-term tolerability and efficacy after initial PegIFN-α addition to dasatinib in CML-CP: Five-year follow-up of the NordCML007 study.

OBJECTIVES: Treatment-free remission (TFR) has emerged as a treatment goal in chronic myeloid leukemia in the chronic phase (CML-CP). Attempts to increase proportion of patients achieving TFR include combination of tyrosine kinase inhibitors (TKI) and other drugs. Interferon-α in addition to TKI has shown promising efficacy but with dose-dependent toxicity and discontinuations. NordCML007 was initiated to study the efficacy and safety of low dose pegylated IFN-α (PegIFN-α) in combination with dasatinib (DAS) in CML-CP. METHODS: Forty patients with newly diagnosed CML-CP were given DAS upfront. After month 3 (M3) 15 µg/wk of PegIFN-α was added and increased to 25 µg/wk from M7 until M15. DAS treatment was continued and adverse events and BCR-ABL1 qRT-PCR values were reported yearly after M24. Results from M1 to M18 have previously been published, and here we present long-term data. RESULTS: After 5 years of follow-up, there were no suspected unexpected serious adverse reactions, no increase in serosal effusions, no disease progressions and no CML-related deaths. Rates of MR3.0 (MMR), MR4.0 and MR4.5 were 84.6%, 64.1% and 51.3% respectively at M60, and 95% of patients reached MMR at some point during the study. CONCLUSION: Initial addition of PegIFN-α to DAS shows good long-term efficacy without increased toxicity.

Immunological monitoring of newly diagnosed CML patients treated with bosutinib or imatinib first-line.

Changes in the immune system induced by tyrosine kinase inhibitors (TKI) have been shown to positively correlate with therapy responses in chronic myeloid leukemia (CML). However, only a few longitudinal studies exist and no randomized comparisons between two TKIs have been reported. Therefore, we prospectively analyzed the immune system of newly diagnosed CML patients treated with imatinib (n = 20) or bosutinib (n = 13), that participated in the randomized BFORE trial (NCT02130557). Comprehensive immunophenotyping, plasma protein profiling, and functional assays to determine activation levels of T and NK cells were performed at diagnosis, 3, and 12 months after therapy start. All results were correlated with clinical parameters such as Sokal risk and BCR-ABL load measured according to IS%. At diagnosis, low Sokal risk CML patients had a higher frequency of cytotoxic cells (CD8 + T and NK cells), increased cytotoxic potential of NK cells and lower frequency of naïve and central memory CD4 + T cells. Further, soluble plasma protein profile divided patients into two distinct clusters with different disease burden at diagnosis. During treatment, BCR-ABL IS% correlated with immunological parameters such as plasma proteins, together with different memory subsets of CD4+ and CD8 + T cells. Interestingly, the proportion and cytotoxic potential of NK cells together with several soluble proteins increased during imatinib treatment. In contrast, no major immunological changes were observed during bosutinib treatment. In conclusion, imatinib and bosutinib were shown to have differential effects on the immune system in this randomized clinical trial. Increased number and function of NK cells were especially observed during imatinib therapy.

Variant-specific discrepancy when quantitating BCR-ABL1 e13a2 and e14a2 transcripts using the Europe Against Cancer qPCR assay.

OBJECTIVE: Molecular monitoring of treatment response in patients with chronic myelogenous leukemia is performed using the Europe Against Cancer (EAC) qPCR assay using the International Scale (IS). The assay amplifies both e13a2 and e14a2 BCR-ABL1 transcript variants. Observing distinct variant-dependent amplification curves during qPCR, we aimed to determine if this affected quantitation of BCR-ABL1. METHODS: We investigated the qPCR efficiency at three Danish diagnostic centers (Zealand University Hospital [ZUH], Aarhus University Hospital [AU], and Rigshospitalet [RH]) on cell lines expressing either the e13a2 or e14a2 BCR-ABL1 transcript variants and compared %IS values from 219 chronic myeloid leukemia patients from the centers with either the e13a2 (n = 113) or e14a2 (n = 106) transcript variants obtained by qPCR with absolute quantitation by droplet digital PCR (ddPCR). RESULTS: Although no significant differences were found in amplification efficiencies of the transcript variants, Bland-Altman analysis of qPCR vs ddPCR values for patient samples revealed a significant average difference in the bias between variants (e3a2/e14a2) of 4.6-, 6.5-, and 1.8-fold for ZUH, AU, and RH, respectively. Furthermore, qPCR %IS values of diagnostic patient samples revealed a significant 4.7-fold difference between the e13a2 and e14a2 variants. CONCLUSION: Our findings suggest that the EAC qPCR assay may underestimate the e14a2 variant compared to the e13a2 variant.

The Danish National Chronic Myeloid Neoplasia Registry.

AIM: The Danish National Chronic Myeloid Neoplasia Registry (DCMR) is a population-based clinical quality database, introduced to evaluate diagnosis and treatment of patients with chronic myeloid malignancies. The aim is to monitor the clinical quality at the national, regional, and hospital departmental levels and serve as a platform for research. STUDY POPULATION: The DCMR has nationwide coverage and contains information on patients diagnosed at hematology departments from January 2010 onward, including patients with essential thrombocythemia, polycythemia vera, myelofibrosis, unclassifiable myeloproliferative neoplasms, chronic myelomonocytic leukemia, and chronic myeloid leukemia. MAIN VARIABLES: Data are collected using standardized registration forms (so far up to four forms per patient), which are consecutively filled out online at time of diagnosis, after 2-year and 5-year follow-ups, and at end of follow-up. The forms include variables that describe clinical/paraclinical assessments, treatment, disease progression, and survival - disease-specific variables - as well as variables that are identical for all chronic myeloid malignancies. DESCRIPTIVE DATA: By the end of 2014, the DCMR contained data on 2,690 patients with an inclusion rate of ∼500 patients each year. Since the registry was established, annual reports have shown consistently high national coverage and data completeness, ≥90% and ≥88%, respectively. CONCLUSION: The DCMR is a national database used for monitoring the quality of patient care in patients with chronic myeloid malignancies, but until validation has been conducted, the data must be used with caution. However, the DCMR is a valuable data source accessible to clinicians and researchers.

Subcellular fractionation of human neutrophils and analysis of subcellular markers.

The neutrophil has long been recognized for its impressive number of cytoplasmic granules that harbor proteins indispensable for innate immunity. Analysis of isolated granules has provided important information on how the neutrophil grades its response to match the challenges it meets on its passage from blood to tissues. Nitrogen cavitation was developed as a method for disruption of cells on the assumption that sudden reduction of the partial pressure of nitrogen would lead to aeration of nitrogen dissolved in the lipid bilayer of plasma membranes. We find that cells are broken by the shear stress that is associated with passage through the outlet valve under high pressure and that this results in disruption of the neutrophil cell membrane while granules remain intact. The unique properties of Percoll as a sedimentable density medium with no inherent tonicity or viscosity are used for creation of continuous density gradients with shoulders in the density profile created to optimize the physical separation of granule subsets and light membranes. Immunological methods (sandwich enzyme-linked immunosorbent assays) are used for quantitation of proteins that are characteristic constituents of the granule subsets of neutrophils.

The expression of ß-microseminoprotein but not CRISP3 is reduced in ovarian cancer and correlates to survival.

BACKGROUND: ß-Microseminoprotein (MSMB) is an abundant protein in seminal plasma. Most of it is present as a free protein but a small part is bound to cysteine-rich secretory protein 3 (CRISP3) as a non-covalent complex. Even though their physiological function is unknown, both MSMB and CRISP3 have been ascribed roles in prostate carcinogenesis. Thus, several recent experimental studies indicate a tumor-suppressor role for MSMB. The present study was undertaken in order to evaluate, for the first time, the expression of MSMB and CRISP3 in ovaries and in ovarian tumors and to determine if their expression might indicate a role in ovarian tumor development. MATERIALS AND METHODS: Biopsies from prospectively collected samples from ovaries and benign, borderline and invasive ovarian tumors were analyzed for expression of MSMB and CRISP3 by immunohistochemistry. In patients with ovarian cancer the expression was compared to survival. RESULTS: Both MSMB and CRISP3 were strongly stained in ovarian epithelial cells and weakly stained in the stroma. In ovarian blood vessels, CRISP3 exhibited strong to medium staining, while MSMB was only weakly expressed. In benign and borderline tumors the staining pattern was similar to the one observed in the ovaries. In invasive neoplasms, the expression of MSMB in the tumor cells was significantly reduced. In univariate analysis, decreased expression of MSMB correlated to reduced survival. No correlation was found with stage, the strongest prognostic indicator for ovarian cancer, which supports an independent role of MSMB in ovarian carcinogenesis. For CRISP3, a staining pattern comparable to that for MSMB was observed in all groups, except the fact that decreased expression was not observed in invasive tumor cells. CONCLUSION: MSMB and CRISP3 were widely distributed in ovaries and in ovarian tumors; the expression of MSMB fits well with a tumor-suppressor function in ovarian carcinogenesis.

Human CRISP-3 binds serum alpha(1)B-glycoprotein across species.

BACKGROUND: CRISP-3 was previously shown to be bound to alpha(1)B-glycoprotein (A1BG) in human serum/plasma. All mammalian sera are supposed to contain A1BG, although its presence in rodent sera is not well-documented. Since animal sera are often used to supplement buffers in experiments, in particular such that involve cell cultures, binding proteins present in sera might interfere in the experiments. METHODS: We examined sera from five different animal species for CRISP-3 binding proteins using gel filtration and ligand blotting. We developed a rapid method for isolation of proteins that bind to human CRISP-3 and identified the isolated proteins by mass spectrometry and N-terminal sequencing. RESULTS: We identified A1BG as a CRISP-3 binding protein in sera from cow, horse and rabbit. CRISP-3 bound kininogen 1 in mouse serum, whereas rat serum showed no CRISP-3 binding activity. In equine serum, we furthermore detected a possible CRISP, already bound to A1BG. GENERAL SIGNIFICANCE: It seems to be a common mechanism that A1BGs bind CRISPs, also across species. Apart from the possible physiological implications hereof, complex binding of CRISPs by A1BG (and other proteins) may interfere with the detection and function of CRISPs, when these are studied in the presence of animal sera.

A model of the complex between human beta-microseminoprotein and CRISP-3 based on NMR data.

beta-Microseminoprotein (MSP), a 10kDa seminal plasma protein, forms a tight complex with cysteine-rich secretory protein 3 (CRISP-3) from granulocytes. The 3D structure of human MSP has been determined but there is as yet no 3D structure for CRISP-3. We have now studied the complex between human MSP and CRISP-3 with multidimensional NMR. (15)N-HSQC spectra show substantial differences between free and complexed hMSP. Using several 3D-NMR spectra of triply labeled hMSP in complex with a recombinant N-terminal domain of CRISP-3, most of the backbone of hMSP could be assigned. The data show that only one side of hMSP, comprising beta-strands 1, 4, 5, and 8 are affected by the complex formation, indicating that beta-strands 1 and 8 form the main binding surface. Based on this we present a tentative structure for the hMSP-CRISP-3 complex using the known crystal structure of triflin as a model of CRISP-3.

Searching biomarker candidates in serum using multidimensional native chromatography. II Method evaluation with Alport syndrome and severe inflammation.

Biomarker search using multidimensional native liquid fractionation of serum in microplates was evaluated. From different donors, homologous sample fractions with UV absorbance depending on state of illness were selected, and their constituents were identified and quantitated by MS. Analysis of sera of patients with Alport syndrome and severe inflammation proved the reliability of the method by confirming characteristic alterations. Moreover, 23 new marker candidates were detected for Alport syndrome, some of them being involved in matrix degradation and repair, and 33 new candidates for severe inflammation, among them alpha1B-glycoprotein cysteine-rich secretory protein and an apparently low molecular-weight albumin variant.

Low salivary dehydroepiandrosterone and androgen-regulated cysteine-rich secretory protein 3 levels in Sjögren's syndrome.

OBJECTIVE: Sjögren's syndrome (SS), an autoimmune disease of exocrine glands, typically starts at the time of adrenopause. We undertook this study to test the hypothesis that SS is characterized by an insufficient androgen effect at the target tissue level. METHODS: We searched for androgen response elements (AREs) in the cysteine-rich secretory protein 3 (crisp-3) gene. Dehydroepiandrosterone (DHEA) responsiveness was experimentally studied using quantitative reverse transcriptase-polymerase chain reaction and immunofluorescence staining of human submandibular gland-derived acinar cells and labial salivary gland explants with or without DHEA. Finally, glandular and salivary CRISP-3 in healthy controls and SS patients was analyzed using immunohistochemistry, in situ hybridization, and enzyme-linked immunosorbent assay. Serum DHEA sulfate (DHEAS) and salivary DHEA levels were measured using a radioimmunometric method. RESULTS: Literature analysis and a search for AREs in gene banks suggested androgen dependency of human CRISP-3, and this was verified by studies of human submandibular gland acinar cells cultured with or without DHEA, in which DHEA increased CRISP-3 messenger RNA (mRNA) levels (P = 0.018). This finding was confirmed by the results of DHEA stimulation of labial salivary gland explants. Glandular CRISP-3 mRNA and protein labeling was weak and diffuse, coupled with low secretion in saliva (mean +/- SEM 21.1 +/- 2.7 mug CRISP-3/15 minutes in SS patients versus 97.6 +/- 12.0 mug CRISP-3/15 minutes in healthy controls; P < 0.0001). Compared with healthy controls, SS patients had low serum levels of DHEAS (P = 0.008) and also low salivary levels of DHEA (mean +/- SEM 224 +/- 33 pmoles versus 419 +/- 98 pmoles; P = 0.005). CONCLUSION: CRISP-3 pathology was seen in acini remote from lymphocyte foci and is apparently not secondary to local inflammation, but may represent some systemic effect in SS. Indeed, androgen deprivation in the salivary glands of SS patients is evidenced both by low salivary levels of DHEA and by low levels of DHEA-regulated CRISP-3. This may explain some of the characteristic features of SS.

Association of cysteine-rich secretory protein 3 and beta-microseminoprotein with outcome after radical prostatectomy.

PURPOSE: It has been suggested that cysteine-rich secretory protein 3 (CRISP-3) and beta-microseminoprotein (MSP) are associated with outcome in prostate cancer. We investigated whether these markers are related to biochemical recurrence and whether addition of the markers improves prediction of recurring disease. EXPERIMENTAL DESIGN: Tissue microarrays of radical prostatectomy specimens were analyzed for CRISP-3 and MSP by immunohistochemistry. Associations between marker positivity and postprostatectomy biochemical recurrence [prostate-specific antigen (PSA) >0.2 ng/mL with a confirmatory level] were evaluated by univariate and multivariable Cox proportional hazards regression. Multivariable analyses controlled for preoperative PSA and pathologic stage and grade. RESULTS: Among 945 patients, 224 had recurrence. Median follow-up for survivors was 6.0 years. Patients positive for CRISP-3 had smaller recurrence-free probabilities, whereas MSP-positive patients had larger recurrence-free probabilities. On univariate analysis, the hazard ratio for patients positive versus negative for CRISP-3 was 1.53 (P=0.010) and for MSP was 0.63 (P=0.004). On multivariable analysis, both CRISP-3 (P=0.007) and MSP (P=0.002) were associated with recurrence. The hazard ratio among CRISP-3-positive/MSP-negative patients compared with CRISP-3-negative/MSP-positive patients was 2.38. Adding CRISP-3 to a base model that included PSA and pathologic stage and grade did not enhance the prediction of recurrence, but adding MSP increased the concordance index minimally from 0.778 to 0.781. CONCLUSION: We report evidence that CRISP-3 and MSP are independent predictors of recurrence after radical prostatectomy for localized prostate cancer. However, addition of the markers does not importantly improve the performance of existing predictive models. Further research should aim to elucidate the functions of CRISP-3 and MSP in prostate cancer cells.

Subcellular fractionation of human neutrophils and analysis of subcellular markers.

The neutrophil has long been recognized for its impressive number of cytoplasmic granules that harbor proteins indispensable for innate immunity. Analysis of isolated granules has provided important information on how the neutrophil grades its response to match the challenges it meets on its passage from blood to tissues. Nitrogen cavitation was developed as a method for disruption of cells on the assumption that sudden reduction of the partial pressure of nitrogen would lead to aeration of nitrogen dissolved in the lipid bilayer of plasma membranes. We find that cells are broken by the shear stress that is associated with passage through the outlet valve under high pressure, and that this results in disruption of neutrophils while leaving granules intact. The unique properties of Percoll as a sedimentable density medium with no inherent tonicity or viscosity are exploited for the creation of continuous density gradients with shoulders in the density profile created to optimize the physical separation of granule subsets and light membranes. Immunological methods (sandwich enzyme-linked immunosorbent assays) are used for quantitation of proteins that are characteristic constituents of the granule subsets of neutrophils.

Haptoglobin is synthesized during granulocyte differentiation, stored in specific granules, and released by neutrophils in response to activation.

Haptoglobin (Hp) is a plasma protein synthesized primarily by hepatocytes. It exerts a broad range of anti-inflammatory activities and acts indirectly as a bacteriostatic agent and an antioxidant by virtue of its ability to bind free hemoglobin (Hb) and to facilitate its immediate clearance by macrophages. We identified Hp as a novel specific granule protein of neutrophils by means of immunoelectron microscopy, subcellular fractionation, and exocytosis studies. Consistent with these findings, blood cells from a patient with specific granule deficiency (SGD) lacked neutrophil-derived Hp. Neutrophils contained a large amount of highly glycosylated Hp (beta-chain 45-65 kDa) synthesized in neutrophil precursors and stored in specific granules and a small amount of Hp (beta-chain 39 kDa) endocytosed from plasma and stored in secretory vesicles. Subsequent binding studies revealed that Hp from specific granules binds to Hb. Finally, the CCAAT enhancer binding protein-epsilon (C/EBPepsilon) induced Hp transcription in a myeloid cell line, suggesting that Hp expression in myeloid cells, as in hepatocytes, is at least partially regulated by members of the C/EBP transcription factor family. Collectively, these findings demonstrate that Hp is stored in specific granules and is released by neutrophils in response to activation. Hence, neutrophil-derived Hp might reduce tissue damage and bacterial growth at sites of infection or injury by propagating anti-inflammatory activities and Hb clearance.

Immunohistochemical detection of cysteine-rich secretory protein 3 in tissue and in serum from men with cancer or benign enlargement of the prostate gland.

BACKGROUND: Recently, the gene for cysteine-rich secretory protein 3 (CRISP-3) was reported to be highly upregulated in prostate cancer (PCa) compared to benign prostatic tissue. The current aims were to investigate diagnostic use of tissue expression and immunodetection in serum of CRISP-3 for detection or monitoring of PCa. METHODS: Radical prostatectomy specimens and tissue microarrays from transurethral resections and metastases were analyzed for CRISP-3 and PSA by immunohistochemistry. CRISP-3 in tissue homogenates and in serum was measured by an in-house ELISA and PSA by a commercially available immunoassay. RESULTS: Immunostaining for CRISP-3 in benign prostatic epithelium was generally weak or not detectable. Specific and strong immunostaining was found in a major proportion of cells in high-grade prostatic-intraepithelial-neoplasia (HG-PIN,12/17 patients), in most primary tumors (111/115), and in lymph node (11/15) and bone (12/15) metastases. CRISP-3 immunostaining intensity was regularly strong in areas of Gleason grades 4/5, where PSA-immunoreaction was less intense. Serum levels of CRISP-3 were not different in patients with PCa (n=152) compared to men with BPH (n=81). There was a very weak co-variation between levels of CRISP-3 versus PSA in serum from PCa patients (P<0.05). After orchiectomy, levels of CRISP-3 in serum decreased in median with 11% compared to a 97% median decrease of PSA in serum from 15/20 patients with advanced PCa. CONCLUSIONS: Strong immunostaining for CRISP-3 is common in HG-PIN and preserved in most PCa specimens, which warrant further immunohistochemical studies of CRISP-3 in PCa. Serum levels of CRISP-3 do not primarily reflect PCa.

Prodefensins are matrix proteins of specific granules in human neutrophils.

Defensins are potent antimicrobial and proinflammatory peptides. The human neutrophil defensins human neutrophil peptide (HNP)-1-3 are synthesized as 94 amino acide (aa) preproHNPs, which are converted to 75 aa proHNPs by cotranslational removal of a 19 aa endoplasmic reticulum signal peptide. At the promyelocytic stage of myelopoiesis, proHNPs are further proteolytically modified and accumulate in azurophil granules as 29-30 aa HNPs. In contrast, proHNPs produced by more mature myeloid cells are not subjected to proteolytic cleavage and undergo a high degree of constitutive exocytosis. The proHNPs are devoid of antimicrobial potential, and the significance of their secretion is unknown. To investigate whether mature neutrophils contain proHNPs, we developed antibodies against proHNP-1 by DNA immunization of rabbits. In addition, antibodies against the 45 aa proHNP pro-piece were raised by conventional immunization procedures. These antibodies allowed detection of proHNPs in homogenates of peripheral blood neutrophils. The proHNPs were isolated by affinity chromatography, and their identity was confirmed by mass spectrometry and N-terminal aa sequence analysis. Finally, the neutrophil proHNPs were identified as novel matrix proteins of specific granules by subcellular fractionation experiments, release studies, and immunoelectron microscopy. Thus, human neutrophils not only store large amounts of mature defensins in azurophil granules but also contain a more easily mobilized reservoir of unprocessed prodefensins in specific granules.

beta-Microseminoprotein binds CRISP-3 in human seminal plasma.

beta-Microseminoprotein (MSP) and cysteine-rich secretory protein 3 (CRISP-3) are abundant constituents of human seminal plasma. Immunoprecipitation and gel filtration of seminal plasma proteins combined with examination of the proteins in their pure form showed that MSP and CRISP-3 form stable, non-covalent complexes. CRISP-3 binds MSP with very high affinity, as evidenced by surface plasmon resonance. Due to far higher abundance of MSP in prostatic fluid, it manifests large overcapacity for CRISP-3 binding. Structural similarity with an MSP-binding protein from blood plasma suggests that CRISP-3 binds MSP through its aminoterminal SCP-domain.

Highly glycosylated alpha1-acid glycoprotein is synthesized in myelocytes, stored in secondary granules, and released by activated neutrophils.

Alpha-1-acid glycoprotein (AGP) is an acute-phase protein produced by hepatocytes and secreted into plasma in response to infection/injury. We recently assessed the transcriptional program of terminal granulocytic differentiation by microarray analysis of bone marrow (BM) populations highly enriched in promyelocytes, myelocytes/metamyelocytes (MYs), and BM neutrophils. These analyses demonstrated a transient, high mRNA expression of genuine secondary/tertiary granule proteins and AGP in MYs. In agreement with this, immunocytochemistry revealed the presence of AGP protein and the secondary granule protein lactoferrin in cells from the MY stage and throughout granulocytic differentiation. Immunoelectron microscopy demonstrated the colocalization of AGP and lactoferrin in secondary granules of neutrophils. This finding was substantiated by the failure to detect AGP and lactoferrin in blood cells from a patient with secondary/tertiary (specific) granule deficiency. In addition, Western blot analysis of subcellular fractions isolated from neutrophils revealed that neutrophil-derived AGP, localized in secondary granules, was abundant and highly glycosylated compared with endocytosed, plasma-derived AGP localized in secretory vesicles. Exocytosis studies further demonstrated a marked release of AGP and lactoferrin by activated neutrophils. Finally, induction of CCAAT/enhancer-binding protein (C/EBP)-epsilon in a myeloid cell line was shown to increase AGP transcript levels, indicating that AGP expression in myeloid cells, like in hepatocytes, is partially regulated by members of the C/EBP family. Overall, these findings define AGP as a genuine secondary granule protein of neutrophils. Hence, neutrophils, which constitute the first line of defense, are likely to serve as the primary local source of AGP at sites of infection or injury.

Characterization and localization of cysteine-rich secretory protein 3 (CRISP-3) in the human male reproductive tract.

Mammalian members of the cysteine-rich secretory protein (CRISP) family are expressed predominantly in the male reproductive tract and are implicated in the process of reproduction from spermiogenesis, posttesticular sperm maturation, and capacitation to oocyte-sperm fusion, and possibly also penetration of the zona pellucida. Rodents express only 2 CRISPs (CRISP-1 and CRISP-2) in their male reproductive system, whereas humans and horses express an additional third member named CRISP-3. We have previously demonstrated that this protein is present in human seminal plasma as well as in other exocrine secretions, in blood plasma, and in neutrophilic granulocytes. To characterize the protein in seminal plasma and localize the production of CRISP-3 in the human male reproductive tract, we performed immunoblotting and enzyme-linked immunosorbent assay measurements of seminal plasma and immunohistochemistry and in situ hybridization of tissue specimens. We were able to show that human CRISP-3 is a quantitatively minor seminal plasma protein not associated with prostasomes. Furthermore, CRISP-3 expression was found in the secretory epithelium throughout the male genital tract, with particularly high expression in the cauda epididymis and ampulla vas deferens. Examination of seminal plasma from vasectomized males indicates that organs downstream of the epididymis are probably the major sources of seminal plasma CRISP-3.

Cysteine-rich secretory protein 3 is a ligand of alpha1B-glycoprotein in human plasma.

Human cysteine-rich secretory protein 3 (CRISP-3; also known as SGP28) belongs to a family of closely related proteins found in mammals and reptiles. Some mammalian CRISPs are known to be involved in the process of reproduction, whereas some of the CRISPs from reptiles are neurotoxin-like substances found in lizard saliva or snake venom. Human CRISP-3 is present in exocrine secretions and in secretory granules of neutrophilic granulocytes and is believed to play a role in innate immunity. On the basis of the relatively high content of CRISP-3 in human plasma and the small size of the protein (28 kDa), we hypothesized that CRISP-3 in plasma was bound to another component. This was supported by size-exclusion chromatography and immunoprecipitation of plasma proteins. The binding partner was identified by mass spectrometry as alpha(1)B-glycoprotein (A1BG), which is a known plasma protein of unknown function and a member of the immunoglobulin superfamily. We demonstrate that CRISP-3 is a specific and high-affinity ligand of A1BG with a dissociation constant in the nanomolar range as evidenced by surface plasmon resonance. The A1BG-CRISP-3 complex is noncovalent with a 1:1 stoichiometry and is held together by strong electrostatic forces. Similar complexes have been described between toxins from snake venom and A1BG-like plasma proteins from opossum species. In these cases, complex formation inhibits the toxic effect of snake venom metalloproteinases or myotoxins and protects the animal from envenomation. We suggest that the A1BG-CRISP-3 complex displays a similar function in protecting the circulation from a potentially harmful effect of free CRISP-3.