Plasma total prekallikrein/kallikrein activity in rheumatoid arthritis with and without amyloidosis. Increased kaolin-stimulated activity in patients with amyloidosis

Following exposure to kaolin, plasma samples were assayed for total prekallikrein/kallikrein activity in 19 patients with rheumatoid arthritis (RA), 39 patients with RA complicated by amyloidosis, 13 patients with nonamyloid nephropathy and 54 healthy subjects. Increased total kallikrein activity was found in RA patients with amyloidosis and in patients with nonamyloid nephropathy. The concentrations of the plasma kallikrein inhibitors C1-inactivator and alpha 2-macroglobulin were normal in RA patients without amyloidosis, whereas they were increased in patients with amyloidosis as well as in patients with nonamyloid nephropathy. The results suggest that the increased activity of plasma kaolin-stimulated kallikrein in RA patients with amyloidosis is due to the nephropathy per se and probably reflects increased levels of prekallikrein.

Determination of transforming growth factor-beta 1 (TGF-beta 1) and insulin-like growth factor (IGF-1) in bovine colostrum samples

The major growth factors in bovine colostrum are transforming growth factor-beta s (TGF-beta 1 and TGF-beta 2) and insulin-like growth factors (IGF-1 and IGF-2). Recently, TGF-beta 2 content of bovine colostrum was measured using a TGF-beta 2 specific ELISA (1) and now we have validated ELISAs for for bovine TGF-beta 1 and IGF-1. The concentrations of IGF-1 and TGF-beta 1 in the first milking after calving were 248-1850 ng/ml and 12.4-42.6 ng/ml, respectively, and they declined in correlation with total protein concentration to 27.0-101 ng/ml (IGF-1) and 0.80-3.49 ng/ml(TGF-beta 1) by the fifth milkings. The amount of TGF-beta 1 was on average 5.3 +/- 1.4% of that of TGF-beta 2 and there is a high correlation (r = 0.966) between the concentrations of these growth factors in the same samples. No free TGF-beta 1 form of could be detected.

Determination of transforming growth factor-beta 2 (TGF-beta 2) in bovine colostrum samples

Transforming growth factor-beta 2 (TGF-beta 2) is the major TGF-beta form in bovine colostrum. A colostrum pool of the five first milkings was made to validate an ELISA specific for human TGF-beta 2 for measure TGF-beta 2 concentration in bovine colostrum samples. According to this test > 90% of total TGF-beta 2 (74.5 +/- 4.4 ng/ml) in colostrum pool was in a latent form that could be activated by acetic acid treatment, whereas the concentration of the active form was only 4.19 +/- 0.27 ng/ml. Activated colostrum samples of the first milkings of five cows contained 150-1150 ng TGF-beta 2/ml and its concentration declined in correlation (r = 0.86) with total protein concentration to 12-71 ng/ml by the fifth milkings. Most of the TGF-beta 2 (94%) was found in the whey fraction of colostrum. The ELISA results were also compared with a TGF-beta 2 bioassay, the fibroblasts migration assay. This assay detected 9.8 +/- 1.0 ng/ml and 4.4 +/- 0.7 ng/ml in the activated and non-activated samples of colostrum pool respectively.

Effects of bovine colostrum supplementation on serum IGF-I, IgG, hormone, and saliva IgA during training

The purpose of this study was to examine the effects of bovine colostrum supplementation (Bioenervi) on serum insulin-like growth factor I (IGF-I), immunoglobulin G, hormone, and amino acid and saliva immunoglobulin A concentrations during a strength and speed training period. Nine male sprinters and jumpers underwent three randomized experimental training treatments of 8 days separated by 13 days. The only difference in the treatments was the drink of 125 ml consumed per day. Posttraining increases were noticed for serum IGF-I in the 25-ml Bioenervi treatment (125 ml contained 25 ml Bioenervi) and especially in the 125-ml Bioenervi treatment (125 ml contained 125 ml Bioenervi) compared with the placebo (normal milk whey) treatment (P < 0.05). The change in IGF-I concentration during the 8-day periods correlated positively with the change in insulin concentration during the same periods with 25-ml Bioenervi treatment (r = 0.68; P = 0.045) and with 125-ml Bioenervi treatment (r = 0.69; P = 0.038). Serum immunoglobulin G, hormone, and amino acid and saliva immunoglobulin A responses were similar during the three treatments. It appears that a bovine colostrum supplement (Bioenervi) may increase serum IGF-I concentration in athletes during strength and speed training.

Viable AC-2, a new adult bovine serum- and colostrum-based supplement for the culture of mammalian cells

In this study we have shown that Viable AC-2, a medium based on the ultrafiltrate fraction of bovine colostrum and adult bovine serum, can be used successfully as a fetal bovine serum (FBS) substitute in the culture of several anchorage-dependent and independent cell lines. Of the 15 cell lines cultured in 8% Viable AC-2 in microplates, 10 reached the maximum cell density of 65%-123% of that in 10% FBS, 4 cell lines reached maximum cell density of 35%-65% of that in 10% FBS and only one cell line, a human osteosarcoma G-292, grew slowly in Viable AC-2. In a small-scale suspension culture, 8%-15% Viable AC-2 supports the growth of Chinese hamster ovary cells (CHO-K1) on microcarriers in spinner flasks significantly better than 10% FBS. Shionogi mouse mammary tumour cell line (S115) transfected with human alpha 2-adrenergic receptor subtype C2 was used as a model to study recombinant protein production in Viable AC-2-supplemented medium. The results showed that in cell culture flasks and in an ACUSYST-R bioreactor, the alpha 2-C2 receptor expression level per mg of total protein was similar in both Viable AC-2 and FBS.

Bovine colostrum ultrafiltrate supplemented with adult bovine serum and transferrin: an effective FBS substitute for cultivation of Vero and CHO-K1 cells

A mixture containing an ultrafiltrate fraction (UF) of bovine colostrum (6.7%), adult bovine serum (BS) (1%), and human holo-transferrin (hTF) (5 mg/liter) was developed for cultivation of Chinese hamster ovary cells (CHO-K1) and African green monkey kidney cells (Vero). The growth-supporting activity of the mixture (UF/BS/hTF) was comparable to that of 1 to 10% fetal bovine serum (FBS) and considerably better than 1 to 2% BS. Cells could be directly seeded from FBS-supplemented medium to UF/BS/hTF-supplemented medium without any weaning period, even at initial plating density of 1700 cells/ml. Vero and CHO-K1 cells were cultivated in UF/BS/hTF-supplemented media for up to 43 days without any apparent reduction in growth. The UF/BS/hTF mixture could also be used as a freezing medium. Cells were passaged twice in the mixture, frozen, and stored at liquid N2 for 11 wk. After thawing, the viability of Vero and CHO-K1 cells was reduced 13 and 7%, respectively, and both cell lines started to grow well. Additional hTF could be replaced with bovine holo-transferrin, although a high concentration (150 mg/liter) should be used for CHO-K1 cells. The results suggest that the UF/BS/hTF mixture provides a new economical alternative to FBS in cultivation of Vero and CHO-K1 cells in the presence of reduced protein amounts.

Bovine colostrum ultrafiltrate: an effective supplement for the culture of mouse-mouse hybridoma cells

An ultrafiltrate fraction (UF) of bovine colostrum has been successfully used as a cell culture supplement for growth and monoclonal IgG antibody production of cultured mouse-mouse hybridomas derived from spleen cells. In this study we compared the ability of UF to support growth and antibody production of IgA hybridomas derived from Peyer's patch cells with that of an IgG hybridoma cell line. One IgG (LPC2) and two IgA hybridoma cell lines (RB3 and P2E7) were used as models. The optimal UF concentration for Ig production and cell growth for both the IgA hybridoma RB3 and the IgG hybridomas was 5-10%. Initial plating density was found to be a critical factor for IgA hybridoma cell growth: the IgA hybridomas required a seeding density of at least 70,000 cells/ml to grow compared to 15,000 IgG hybridoma cells/ml (Pakkanen et al., 1992). The addition of small amounts (up to 2%) of FBS in 10% UF supplemented medium did not enhance IgA production or cell growth. RB3 and LPC2 cells seeded at equal density and grown in 10% UF for 8 days attained maximum cell densities at 3-4 days that were 58% (RB3) or 34% (LPC2) lower than those in 10% FBS, but the total amounts of monoclonal antibody produced were 73% and 83%, respectively, of that in 10% FBS. Thus, Ig production per cell was 22-27% higher in 10% UF than in 10% FBS. Hybridoma cells could be cultured for at least 5 weeks without any reduction in growth rates, if medium was partially but not completely replaced twice a week. This suggests that hybridoma cells maintained in UF supplemented medium secrete growth promoting factors. Cells maintained in UF for up to 5 weeks sustained similar monoclonal antibody production rates as in short term culture. These results show that UF can be used as an economical and effective hybridoma culture supplement for the production of both IgG and IgA antibodies.

Cloning and sequencing of a gene encoding acidophilic amylase from Bacillus acidocaldarius

Two starch-degrading enzymes produced by Bacillus acidocaldarius (renamed as Alicyclobacillus acidocaldarius) were identified. According to SDS-PAGE, the apparent molecular masses of the enzymes were 90 and 160 kDa. Eight peptide fragments and the N-terminal end of the 90 kDa polypeptide were sequenced. An oligonucleotide, based on the amino acid sequence of a peptide fragment of the 90 kDa protein, was used to screen a lambda gt10 bank of B. acidocaldarius, and the region encoding the 90 kDa protein was cloned. Unexpectedly, the ORF continued upstream of the N terminus of the 90 kDa protein. The entire ORF was 1301 amino acids (aa) long (calculated molecular mass 140 kDa) and it was preceded by a putative ribosomal binding site and a promoter. Computer analysis showed that the 1301 aa protein was closely related to an alpha-amylase-pullulanase of Clostridium thermohydrosulfuricum. We suggest that the starch-degrading 160 kDa protein of B. acidocaldarius is an alpha-amylase-pullulanase, and the 90 kDa protein is a cleavage product of the 160 kDa protein. Another ORF, apparently in the same transcription unit, was found downstream from the amylase gene. It encoded a protein that was closely related to the maltose-binding protein of Escherichia coli.

S-layer protein gene of Lactobacillus brevis: cloning by polymerase chain reaction and determination of the nucleotide sequence

The surface (S)-layer protein of Lactobacillus brevis was isolated, purified, and characterized. The S-layer protein is the major protein of the cell, with an apparent molecular mass of 46 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunogold electron microscopy with polyclonal antiserum against the isolated 46-kDa protein was used to confirm the surface location of this protein. N-terminal amino acid sequences of the intact 46-kDa protein and its tryptic peptides were determined. The gene of the S-layer protein was amplified from the genome of L. brevis by polymerase chain reaction with oligonucleotides, synthesized according to the N-terminal amino acid sequences, as primers. The polymerase chain reaction fragments containing the entire S-layer gene and its regulatory regions were sequenced. Nucleic acid sequence analysis revealed one open reading frame with a capacity to encode a protein of 48,159 Da. From the regulatory region of the gene, two subsequent promoters and a ribosome binding site, showing typical features of prokaryotic consensus sequences, were found. The coding region contained a characteristic gram-positive-type signal peptide of 30 amino acids. Removal of the signal peptide results in a polypeptide of 435 amino acids, which is in excellent agreement with the size of the S-layer protein determined by SDS-PAGE. The size and the 5' end analyses of the S-layer transcripts confirmed the monocistronic nature of the S-layer operon and the functionality of the two promoters found.

Bovine colostrum fraction as a serum substitute for the cultivation of mouse hybridomas

Fractions of bovine colostrum were prepared and their ability to support the growth of mouse-mouse hybridomas in culture was tested. Whey was prepared from defatted colostrum by removal of casein using acid precipitation. An ultrafiltrate was obtained from cleared whey by filtration through membranes with a nominal molecular mass cut-off of 100,000 Da. Colostrum ultrafiltrate contained 1.16 milligrams protein, 0.24 milligrams immunoglobulin G (IgG) and less than 0.24 EU (endotoxin unit)/ml endotoxins. The effect of defatted colostrum, whey and ultrafiltrate as serum substitutes was examined by cultivation of hybridoma cells in minimal essential medium containing different concentrations of the supplements. Under optimal conditions in ultrafiltrate-supplemented medium, the maximal cell concentration was 35-40% of that obtained using 10% foetal bovine serum, and IgG production per cell was equal to that achieved using serum. In 1% defatted colostrum the maximum hybridoma concentration was about 30% of that in 10% serum, but at higher concentrations hybridoma growth was significantly reduced. The growth-promoting activity of whey was low. The results show that bovine colostrum ultrafiltrate provides a very attractive alternative to serum for production of monoclonal antibodies.

Expression of the Erwinia carotovora polygalacturonase-encoding gene in Bacillus subtilis: role of signal peptide fusions on production of a heterologous protein

The pehA gene encoding an endopolygalacturonase (pectinase) of Erwinia carotovora subsp. carotovora has been cloned previously [Saarilahti et al., Mol. Microbiol. 4 (1990) 1037-1044]. We expressed pehA in Bacillus subtilis using a secretion vector based on the promoter and signal sequence of the alpha-amylase (Amy)-encoding gene, amyE, from Bacillus amyloliquefaciens. To test whether the location of the junction between the secretion vector and pehA affects the protein yield, we made four different junctions. Two constructs contained an intact Amy signal sequence, whereas the other two were fusions between the Amy signal sequence and the polygalacturonase (PG) signal sequence. There was approximately fourfold variation in the production efficiency of B. subtilis strains carrying the different constructs. The most efficient construct contained the N-terminal and hydrophobic regions of the Amy signal peptide joined to the C terminus of PG signal peptide. This construct produced, in a shake flask culture, 0.8 g of polygalacturonase per liter of growth medium. In a pulse-chase experiment, the signal peptide of the most efficient construct was rapidly cleaved while cleavage was slow in the other constructs. Our results suggest that fusions containing intact signal peptides, which are common when producing foreign proteins, are not necessarily the most efficient.

Production of pectin methylesterase from Erwinia chrysanthemi B374 in Bacillus subtilis

The gene coding for pectin methylesterase (PME) of Erwinia chrysanthemi B374 (pme) was cloned by a polymerase chain reaction. The pme gene was expressed in Bacillus subtilis using a secretion vector based on the promoter and signal sequence of the alpha-amylase gene from B. amyloliquefaciens. The cultivation of B. subtilis cells carrying the cloned pme resulted in efficient secretion of PME into the culture medium based on enzymatic and sodium dodecyl sulphate-poly-acrylamide gel electrophoresis characterizations. The NH2-terminal sequence analysis of the secreted PME revealed two different NH2-termini. Heterologous processing was probably due to a second putative signal peptidase cleavage site at the joint region between the PME and alpha-amylase signal peptide.

Structural analysis of the pehA gene and characterization of its protein product, endopolygalacturonase, of Erwinia carotovora subspecies carotovora

A clone producing a polygalacturonase (EC 3.2.1.15) in Escherichia coli was isolated from a genomic library of Erwinia carotovora subspecies carotovora constructed in PUC18. The DNA segment carrying the corresponding structural gene, named pehA, contained an open reading frame (ORF) encoding a 402-amino-acid (aa) polypeptide with an Mr of 42,849. In E. carotovora the polygalacturonase was synthesized with a 26-aa cleavable signal peptide. The mature 376-aa PehA had a calculated Mr of 40,064 and a pl of 10.19. The pH optimum of the enzyme was about 5.5 and the temperature optimum was in the range 35-45 degrees C. Analysis of the reaction products of polygalacturonic acid hydrolysis indicated that the PehA protein is an endopolygalacturonase. No similarity was observed between the aa sequences of PehA and other pectic enzymes of erwinias. However, substantial similarity was detected within the C-terminal portions of PehA and a previously described tomato polygalacturonase, suggesting that the bacterial and eukaryotic polygalacturonases may have a common origin.

Cytovillin, a microvillar Mr 75,000 protein. cDNA sequence, prokaryotic expression, and chromosomal localization

Cytovillin is a microvillar cytoplasmic peripheral membrane protein, with prominent expression in vivo in placental syncytiotrophoblasts and certain human tumors. Cytovillin cDNA was cloned from a human placental lambda gt11 library using affinity purified antibodies. The identity of cytovillin cDNA clones was confirmed by expression of cytovillin in Escherichia coli and using antibodies raised against the expressed fusion protein in comparison with antibodies against cytovillin purified from cultured human choriocarcinoma cells. In these cells Northern blotting analysis identified a major 3.5-kilobase cytovillin mRNA. The cDNA encodes a protein of 575 amino acids corresponding to a molecular weight of 68,084. According to secondary structure prediction, cytovillin is a hydrophilic protein with an extensive internal alpha-helical region ending in a sequence of 7 consecutive prolines. The predicted alpha-helical region showed limited homology to alpha-helical regions of cytoskeletal proteins and certain other proteins, but no extensive homologies were found in the cytovillin cDNA or the deduced amino acid sequence to other registered DNA or protein sequences. Southern blot analysis of a DNA panel of human mouse somatic cell hybrids localized the cytovillin gene to the end of the long arm of chromosome 6 (6q22-q27). Our results show that cytovillin is representative of a novel class of microvillar proteins.

Cytovillin and other microvillar proteins of human choriocarcinoma cells

Microvilli were isolated from cultured human JEG-3 choriocarcinoma cells using a gentle shearing method. The protein components of the isolated microvilli were examined by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The major Mr 42,000 and Mr 100,000 polypeptide bands reacted with anti-actin and anti-alpha-actinin antisera, respectively. Extraction of the isolated JEG-3 microvilli with Triton X-100 left an insoluble cytoskeletal residue containing mainly actin, alpha-actin, and polypeptides of Mr 200,000, 55,000 and 35,000. The Mr 35,000 polypeptide remained insoluble only at high concentrations of free Ca2+. Immunoblotting analysis of the JEG-3 microvilli indicated that they were devoid of tropomyosin, although the total JEG-3 protein lysates gave a strong positive reaction with anti-tropomyosin antiserum. The different subcellular localization of cytovillin and tropomyosin was also shown by indirect immunofluorescence microscopy. Cytovillin, an Mr 75,000 microvillus-specific membrane protein of JEG-3 cells, existed in an oligomeric form (dimer or trimer) as shown by gel filtration of Triton X-100 solubilized microvillar proteins and by native polyacrylamide gel electrophoresis of purified cytovillin. Disulfide bridges were not involved in the aggregation, because the mobility of cytovillin was similar under reducing and nonreducing conditions in SDS-PAGE. Cytovillin was shown to be closely related to ezrin, a minor component of chicken intestinal brush border microvilli.

Immunofluorescent and immunochemical evidence for the expression of cytovillin in the microvilli of a wide range of cultured human cells

We have previously purified a Mr 75,000 protein, cytovillin, from cultured human choriocarcinoma cells (JEG-3) and shown that this protein was specifically confined to the microvillus membrane of these cells. I have now studied the expression and the subcellular distribution of cytovillin in eighteen normal and transformed human cell lines and strains by using immunoblotting and indirect immunofluorescence microscopy. In all cell types, cytovillin was highly enriched in cell surface protrusions. When cell types were ranked according to their staining intensity, choriocarcinoma was highest, then amniotic epithelial cells, other choriocarcinoma cells and tumor cells, and finally fibroblastoid cells. The latter only gave faint diffuse fluorescence on the plasma membrane and, occasionally, on the microvilli. However, detergent extracts of all cell types could be shown to contain cytovillin by the use of immunoblotting techniques. Metabolic pulse-chase labelling experiments with JEG-3 cells demonstrated synthesis of cytovillin as a single-chain polypeptide. No precursor forms or specific proteolytic cleavage products could be seen either by immunoblotting or immunoprecipitation. The protein was found to be very stable with a biologic half-life of about 25 hours. The pI determined by isoelectric focusing was 6.1. These results were consistent with cytovillin being an integral component of the microvilli and other surface extensions of all human cell types examined.

Redistribution of Mr 75,000 plasma membrane protein, cytovillin, into newly formed microvilli in herpes simplex and Semliki Forest virus infected human embryonal fibroblasts

We have previously purified an Mr 75,000 protein from cultured human JEG-3 choriocarcinoma cells and showed that this protein is specifically confined to the cytoplasmic side of JEG-3 microvillar membranes. Recently, the Mr 75,000 protein, designated as cytovillin, was found to be expressed also in several other cultured human cell lines and strains, in which it was detected in microvillus-related structures. We now demonstrate the redistribution of cytovillin in herpes simplex type 1 (HSV-1) and Semliki Forest virus (SFV) infected human embryonal fibroblasts. Virus infection induced rapidly numerous microvilli on the apical cell surfaces, and cytovillin was enriched into these newly formed structures as shown by indirect immunofluorescence and immunoferritin electron microscopy. In mock-infected cells treated with the anti-cytovillin antibodies a small amount of ferritin particles and faint fluorescence was detected along the smooth plasma membrane. Only occasional cell surface protrusions were observed in these cells. The enrichment of the cytovillin was first seen 2 h after infection. The isoelectric point (IP) and the mobility of the cytovillin polypeptide in sodium dodecyl sulfate polyacrylamide gel electrophoresis was not altered after this redistribution, suggesting that the protein was not significantly modified during infection. Five RNA+ SFV mutants (ts-1, ts-2, ts-3, ts-5, ts-7) with temperature-sensitive defects in processing and transport of viral envelope glycoproteins to the plasma membrane induced microvilli at the restrictive temperature (39 degrees C) as the wild type virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvillus-specific Mr 75,000 plasma membrane protein of human choriocarcinoma cells

We have previously purified from cultured JEG-3 choriocarcinoma cells an Mr 75,000 protein, originally detected using antibodies to a retrovirus-related synthetic peptide. Using polyclonal antibodies, we have now localized this protein immunocytochemically in JEG-3 cells at both light and electron microscopic levels. In immunofluorescence microscopy of saponin-permeabilized cells, the antigen appeared as dots and short strands at the apical cell surface. In pre-embedding immunoperoxidase electron microscopy, the Mr 75,000 protein was specifically localized to microvilli on the apical cell surface. Immunoferritin electron microscopy was used to assess more quantitatively the antigen distribution in the plane of the plasma membrane, and to define the position of the antigenic site(s) with respect to the membrane. The immunoferritin results confirmed the microvillus specificity of the Mr 75,000 protein and showed that the antigenic portion of the protein is within a few nanometers from, and on the cytoplasmic side of, the lipid bilayer. In detergent extraction experiments, the Mr 75,000 antigen was highly enriched in the soluble fractions. These results demonstrate that the Mr 75,000 protein is a membrane protein highly specific for microvilli.

Induction of large granular lymphocyte morphology in human peripheral blood mononuclear cells

The transformation of human agranular blood lymphocytes into large granular lymphocytes (LGL) was studied. On the average, 2.8% of peripheral blood lymphocytes differentiate in less than 24 hr into LGL when cultured with autologous plastic-adherent monocytes and the Burkitt's lymphoma cell line Raji. The LGL precursors were intermediate-density lymphoid cells that were heterogenous for T3, T8, and Leu-7 antigens, negative for T4 and Leu-11, and positive for NK-9. During the transformation, frequency of Leu-11-positive cells increased and the cytotoxic activity was augmented. In single cell cytotoxicity experiments, the number of binding cells increased, whereas the number of killer cells among the binding cells remained unaltered. The transformation inducing factor was detectable in coculture supernatants of Raji and monocytes or Raji and the myeloid cell line ML-2. Analyses of the Raji-ML-2 coculture supernatants with reverse phase and gel filtration high-pressure liquid chromatography indicated that the factor is a heat- and trypsin-sensitive hydrophilic molecule with an apparent m.w. of 1000.

Induction of large granular lymphocyte morphology in human peripheral blood mononuclear cells

The transformation of human agranular blood lymphocytes into large granular lymphocytes (LGL) was studied. On the average, 2.8% of peripheral blood lymphocytes differentiate in less than 24 hr into LGL when cultured with autologous plastic-adherent monocytes and the Burkitt's lymphoma cell line Raji. The LGL precursors were intermediate-density lymphoid cells that were heterogenous for T3, T8, and Leu-7 antigens, negative for T4 and Leu-11, and positive for NK-9. During the transformation, frequency of Leu-11-positive cells increased and the cytotoxic activity was augmented. In single cell cytotoxicity experiments, the number of binding cells increased, whereas the number of killer cells among the binding cells remained unaltered. The transformation inducing factor was detectable in coculture supernatants of Raji and monocytes or Raji and the myeloid cell line ML-2. Analyses of the Raji-ML-2 coculture supernatants with reverse phase and gel filtration high-pressure liquid chromatography indicated that the factor is a heat- and trypsin-sensitive hydrophilic molecule with an apparent m.w. of 1000.

Mr 75,000 protein, a tumor marker in renal adenocarcinoma, reacting with antibodies to a synthetic peptide based on a cloned human endogenous retroviral nucleotide sequence

Using a rabbit antiserum to a synthetic undecapeptide deduced from a cloned human retroviral gag-gene-related DNA sequence, we found a specific immunohistochemical reaction in all of 42 tested renal cell adenocarcinomas (RCC), while none of 17 similarly tested Wilms' tumors and 65 carcinomas at other sites were positive. The RCC included two cases that presented with distant metastases. It had not been possible to establish the origin of these until immunohistochemical staining revealed this typical reaction. Subsequent renal angiography disclosed the primary. In immunoblotting the antiserum detected an Mr 75,000 protein in RCC tissue, and this reaction was blocked by the undecapeptide. The usefulness of this protein as a tumor marker for RCC is discussed.

Human placental syncytiotrophoblastic Mr 75,000 polypeptide defined by antibodies to a synthetic peptide based on a cloned human endogenous retroviral DNA sequence

Antibodies to a synthetic undecapeptide (NH2-Cys-Glu-Asn-Pro-Ser-Gln-Phe-Tyr-Glu-Arg-Leu-COOH), the sequence (except cysteine) of which was deduced from a previously reported cloned human retroviral gag-gene-related DNA sequence erv-1, were raised in rabbits. In immunohistochemical staining these antibodies reacted with normal human first-trimester placentas and with blighted ova and benign and malignant trophoblastic tumors (hydatidiform and destructive moles, choriocarcinomas) but not with any other normal embryonic or adult tissues tested. In all tissues the reactivity was mainly confined to cells with trophoblastic morphology. In immunoblotting the antibody detected an Mr 75,000 polypeptide in syncytiotrophoblasts isolated from first-trimester placentas and in three different lines of cultured choriocarcinoma cells. The undecapeptide blocked the reactivity of the antibody.