Expression and secretion of chicken apolipoprotein AI in transfected COS cells

A full-length chicken apolipoprotein A-I (apoAI) cDNA has been cloned into an expression vector, pRSVapoAI. This plasmid was transfected into a monkey kidney (COS-1) cell line in order to study apolipoprotein-lipid assembly. Chicken apoAI is the major apolipoprotein of chicken high-density lipoprotein (HDL), which is less complex in apolipoprotein content than the HDL of human plasma. The transient transfected COS-1 cells synthesized and secreted authentic plasma apoAI. Under serum-free medium conditions, COS cells secreted only proapoAI. A small portion (15%) of the secreted apoAI floated at a density 1.07-1.20 g/ml. Upon incubation with fetal bovine serum at 10 degrees C, a majority of the apoAI was recovered in the HDL density (1.06-1.20 g/ml) region. Secreted apoAI was labeled when transfected COS cells were incubated with [U-14C]palmitate, but the incorporation of radioactivity was not the result of fatty acid acylation through ester bond formation. These results indicate that heterologous COS-1 cells are capable of synthesizing and secreting apoAI, and that intracellular association of apoAI with lipids is not necessary for secretion.

Detection of haemophilia A traits in carriers

Obligate carriers of haemophilia A and normal women matched for age were studied in order to find a suitable parameter for detection of carriers of haemophilia A. The ratio of factor VIII coagulant activities (F VIIIC) to factor VIII related antigen (F VIII R : Ag) was 0.55 in obligate carriers and 1.0 in non-carrier females.

Ferritin release by mononuclear cells in hereditary hemochromatosis

An anomaly of the iron-loading disorder hereditary hemochromatosis is that bone marrow iron stores remain low until later stages of the disease. The possibility that this may be related to a disorder of reticuloendothelial ferritin metabolism was examined by studying ferritin release from mononuclear cells. Ferritin release was measured in peripheral blood mononuclear cells from four patients with hemochromatosis who had not received treatment, from six patients with hemochromatosis who had received treatment, and from 10 age- and gender-matched controls by using a modified hemolytic plaque assay. Ferritin release from the hemochromatotic cells was enhanced when compared with that of controls, and added iron stimulated ferritin release to a comparable degree in both groups. Enhanced ferritin release above matched control values was found both in cells from patients with hemochromatosis with partial phlebotomy who had high serum ferritin values and in cells from patients with hemochromatosis with full phlebotomy who had normal serum ferritin values. The increased ferritin release observed in these studies may signify abnormal reticuloendothelial iron metabolism in hemochromatosis.

A simple method for preparation of good quality cryoprecipitate

Production of good quality cryoprecipitate from plasma was achieved, as assessed by quantitating Factor VIII coagulant activity (F VIII C) and Factor related antigen (F VIII R: Ag). The method used resulted in good recovery of FVIII in the cryoprecipitate containing F VIII C: Fibrinogen 0.82 +/- 0.015 IU/mg. The method therefore appears suitable for indigenous preparation of F VIII in standard blood banks as a replacement therapy, which is not expensive.

T-cell-mediated protection of mice against virulent Mycobacterium tuberculosis

We sought to protect CBA mice against tuberculosis using in vivo transfer of a T-cell line previously shown to be capable of I-A-restricted recognition of peritoneal macrophages infected in vitro with Mycobacterium tuberculosis. This line induces total bacteriostasis in vitro. In mice that received 500 rads of irradiation 48 h before infection, the T-cell line caused significant prolongation of life when given intravenously with a challenge dose of 5 x 10(6) organisms. Similar experiments with two other T-cell lines showed that these lines offered no protection. Bacterial load at the time of death was inversely related to the time of survival. Thus, death occurred at a lower bacterial load in adoptively protected mice, implying the contribution of an immunopathological component in these animals. The protective T-cell line, which was CD4+ CD8-, had no effect on the rate of growth of strain BCG in CBA nu/nu mice or M. tuberculosis in fully T-cell-deprived mice. This could indicate that CD8+ cells play a role in this system or that there is a need for the recruitment of interleukin 2-producing cells in the recipient. Experiments with monoclonal antibodies to selectively deplete T-cell subsets in normal CBA mice showed that depletion of CD4+ cells strikingly shortened survival, whereas depletion of CD8+ cells did not. However, CD8-depleted mice died with a lower bacterial load than those found in nondepleted controls, and the lesions in CD8-depleted mice were histopathologically distinct. These results suggest that the CD8+ cells either down-regulate bacteriostasis or cause immunopathology in this model and that it is the CD4+ cells that are the major protective subset in long-term protection experiments.

Immunohistochemical localization of metallothionein in human testicular embryonal carcinoma cells

The presence of high levels of metallothionein (MT) in developing mammalian cells is well documented. It has been suggested that the developmental profile and gene expression of MT is similar to that of the so-called oncodevelopmental gene products such as a-fetoprotein. In this study tissue sections of nine human embryonal carcinomas of the testis were tested by means of the avidin-biotin peroxidase complex for the presence of MT. The antigen was localized in variable amounts in the cytoplasm and nucleus in tumour cells in all cases. There was evidence that immunoreactivity was related to the histological growth pattern of tumour cells. These findings suggest that MT may be considered an oncodevelopmental product which could be useful as a tumour marker. In addition, the histology of these tumours might predict MT expression; this may prove of value in testing the hypothesis of MT-related emergence of drug-resistant cell lines in the course of treatment of tumours with metal-containing chemotherapeutic agents.

Retinoic acid inhibits phospholipid turnover and protein kinase C activity in RA-sensitive but not in RA-resistant cells

Treatment with 10(-5) M retinoic acid causes loss of anchorage-independent growth in src-transformed RR1022 cells but not in ras-transformed KNRK cells. In an effort to elucidate the mechanisms underlying this difference, we investigated the effect of RA on phospholipid turnover and PKC activity in these two cell lines. 10(-5) M RA treatment caused a drastic inhibition of 32P incorporation into PI and PA and a large increase in 32P incorporation into PC in RR1022 cells. Similar treatment of KNRK cells yielded no change in PC or PA labelling and a much smaller decrease in PI labelling. Furthermore, 10(-5) M RA treatment causes a large decrease in PKC activity in RR1022 cells (35% of control) but only a small decrease in KNRK cells (78% of control). We suggest that these effects are part of an altered signal transduction pathway which mediates the differential effects of RA on anchorage-independent growth in these two cell lines.

Transferrin receptor and 4F2 expression by NK-sensitive and NK-resistant tumour cell lines

Upon stimulation with a phorbol ester and known tumour promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), the human erythroleukemia K562 cell line, a standard target for human natural killer (NK) cells, shows a significant reduction in expression of transferrin receptors (TfR) and becomes resistant to NK-mediated cytolysis. Prompted by the initial finding that expression of TfRs by K562 cells correlates with target sensitivity to NK cytotoxicity, we have investigated the role of two proposed NK-target structures, the TfR and 4F2 molecule in three other tumour cell lines which vary in their susceptibility to NK activity. We report that similar to K562 cells, MOLT 4, Raji and HL60 cells demonstrate phorbol-ester-induced down-regulation of TfR expression. The expression of TfRs alone does not determine target sensitivity. However, TfRs are probably located close to the NK-target structure in NK-sensitive cell lines. Based on the properties of phorbol ester induction, it is possible that the NK-target molecule is down-regulated in response to phorbol ester induction in a similar, if not identical manner to that of the TfR; thus, rendering NK-sensitive cells resistant to NK killing, after TPA exposure. Conversely, the target molecule is probably upregulated in MOLT 4 cells after TPA treatment as indicated by the acquired sensitivity of these cells to NK-mediated cytolysis. The expression of 4F2 molecules was not influenced by TPA treatment and does not correlate with NK sensitivity.

Flow cytometric analysis of the phenotypic changes in tumour cell lines following TPA induction

Single-cell analysis by flow cytometry has enabled us to analyze the effects of a phorbol ester and known tumour promoter, TPA, on the phenotypes of four tumour lines. TPA is capable of triggering a variety of cellular alterations that can affect gene expression and the biochemical balance of intracellular events. We have investigated the effect of TPA on such properties as rate of proliferation, differentiation, expression of cell surface molecules, and susceptibility to natural killer (NK) cell-mediated cytolysis. Four human leukemia and lymphoma cell lines; K562, MOLT 4, Raji, and HL60, were studied in their response to TPA treatment. Based on measurements of the defined cellular properties, we have characterized the pleiotropic responses of each tumour cell line to the phorbol ester in relation to intensity and time of onset of each response. The effects of TPA are highly varied, ranging in time of onset from minutes to days, and in intensity from strong to weak within the four cell lines studied. However, within all the processes that are affected, the activation of protein kinase C appears to be a common initiating event of phorbol ester induction.

Localization of the McLeod locus (XK) within Xp21 by deletion analysis

The McLeod phenotype is an X-linked, recessive disorder in which the red blood cells demonstrate acanthocytic morphology and weakened antigenicity in the Kell blood group system. The phenotype is associated with a reduction of in vivo red cell survival, but the permanent hemolytic state is usually compensated by erythropoietic hyperplasia. The McLeod phenotype is accompanied by either a subclinical myopathy and elevated creatine kinase (CK) or X-linked chronic granulomatous disease (CGD). Seven males with the McLeod red-blood-cell phenotype and associated myopathy but not CGD, one male with the McLeod phenotype associated with CGD, and two males known to possess large deletions of the Duchenne muscular dystrophy (DMD) locus were studied. DNA isolated from each patient was screened for the presence or absence of various cloned sequences located in the Xp21 region of the human X chromosome. Two of the seven males who have only the McLeod phenotype and are cousins exhibit deletions for four Xp21 cloned fragments but are not deleted for any portion of either the CGD or the DMD loci. Comparison of the cloned segments absent from these two McLeod cousins with those absent from the two DMD boys and the CGD/McLeod patient leads to the submapping of various cloned DNA segments within the Xp21 region. The results place the locus for the McLeod phenotype within a 500-kb interval distal from the CGD locus toward the DMD locus.

Suppression of immunoglobulin production by germinal centre HNK-1+ CD3+ cells

Germinal centre T cells co-expressing HNK-1 antigen have little lytic activity against NK targets (K562 cells). In order to determine whether these cells regulate B cell function, they were purified from human tonsils by panning on anti-HNK-1 antibody coated Petri dishes and co-cultured with autologous and allogeneic tonsillar T and B cells in the presence of pokeweed mitogen. At the end of 7 days of culture, supernatants were assayed for immunoglobulin concentration by ELISA. A dose-dependent suppression of both IgG and IgM production was demonstrated at ratios from 1:125 to 1:16 of HNK-1+ cells to B cells, but enhancement was observed at very low ratios (less than 1:500) or ratios exceeding 1:16 in some tonsil preparations. Similar results were obtained with peripheral blood HNK-1+ cells but without enhancement in some cases at the extremes of HNK-1+ cells to B cell ratios. The suppression was not MHC-restricted. These preliminary experiments indicate that germinal centre HNK-1+ cells may be intrafollicular suppressor cells.

Epidermal and transforming growth factors modulate secretion of a 69 kDa phosphoprotein in normal rat kidney fibroblasts

Our study shows that the secretion of a major non-glycosylated, phosphoprotein of 69 kDa (pp69) is a specific marker for non-transformed NRK-49F cells. Treatment of NRK-49F cells with EGF alone or with different combinations of EGF plus TGF-beta modulates the secretion of pp69, suggesting its relationship with cellular proliferation. Antibody raised against pp69 recognizes, in addition to pp69, another major phospho-protein of 62 kDa (pp62) secreted by RR1022 and spontaneously transformed NRK-49F cells. Immunoprecipitation of total cell lysates from both NRK-49F and RR1022 cells with anti-pp69 antibody detected only pp69. These observations suggest a precursor-product relationship between pp69 secreted by non-transformed NRK-49F cells and pp62 secreted by transformed cells.

Immunohistochemical localization of metallothionein in human thyroid tumors

High levels of metallothionein (MT) are present in the developing mammalian liver; however, a remarkable decrease is observed during postnatal life after weaning. This developmental profile is similar to that of certain oncofetal gene products such as alpha-fetoprotein, which is used as a tumor marker. This study deals with the reexpression of MT genes in thyroid tumors. With an immunohistochemical method, the presence of MT was investigated in tissue sections of normal and neoplastic human thyroid glands. Tissue sections of 34 thyroid tumors and 10 normal human thyroid glands were studied by means of the peroxidase-antiperoxidase method. MT was localized in 31 of the thyroid gland tumors. MT was also present in two of the normal thyroid glands. These findings indicate that although high levels of MT are mainly found in the fetal liver, it may also be expressed actively in certain human thyroid neoplastic tissues, and occasionally in normal thyroid tissue.

Immunohistochemical localization of metallothionein in cell nucleus and cytoplasm of fetal human liver and kidney and its changes during development

The distribution of metallothionein (MT) during human development was investigated using both immunohistochemical and biochemical methods. The level of MT in the fetal liver was higher than the adult liver levels. Higher levels of zinc (Zn) and copper (Cu) were also detected in the fetal liver compared to the adult liver. Although cadmium (Cd) was present in detectable levels in the human adult liver, none was detected in the human fetal liver. MT was localized in the nucleus and the cytoplasm of human fetal and neonatal hepatocytes, using a specific rabbit antibody raised to rat liver MT. In the adult human liver cells, MT was localized mainly in the cytoplasm. In the fetal and neonatal human kidney, MT was localized mainly in the nucleus and the cytoplasm of the proximal tubular epithelial cells. In the adult kidney, in addition to nuclear-cytoplasmic localization of MT, intraluminal localization was also observed.

The role of insulin resistance in the pathogenesis of myotonic muscular dystrophy

A study of glucose, insulin, lipids and lipoproteins in myotonic dystrophy (MyD) has shown elevation of fasting plasma insulin, triglycerides and very low density lipoproteins (VLDL) but no significant difference from normal in the fasting plasma glucose, total cholesterol or low and high density lipoproteins. Elevation of the total triglyceride and VLDL levels showed a direct relationship to hyperinsulinaemia. Insulin binding to cultured MyD fibroblasts under optimal conditions was significantly reduced but there was no difference in receptor affinity between MyD and control cells. In contrast to insulin binding, LDL binding to MyD fibroblasts was normal although there was a tendency to reduced LDL binding at 37 degrees C that may reflect mildly reduced lipid metabolism. The alterations in lipids and insulin in MyD are compatible with insulin resistance. Laboratory and clinical findings in MyD were compared with other inherited insulin-resistant diseases. MyD showed marked similarity to a group of disorders that have mild insulin resistance and mildly elevated plasma insulin in contrast to others with severe hyperinsulinaemia and insulin resistance. It is suggested that at least some clinical features of MyD may be due to diminished overall effect of insulin or other trophic factors on cell metabolism.

Cross reactivity of a monoclonal pan T-cell antibody (anti-Leu 4) with prostate epithelium

Cross reactions between monoclonal T-cell antibodies and non-lymphoid tissues have rarely been reported. In this study 28 samples of prostatic tissue obtained at the time of autopsy or surgery, two samples of metastatic prostatic carcinoma and a series of other tumours were snap frozen and sections reacted with a series of monoclonal antibodies directed against the following antigens: Leu 1, Leu 4, T3, T8, T4, T11 and B4. Reactions were detected with an indirect immunofluorescent method. In 10 of 11 normal prostates, 15 of 15 with nodular hyperplasia and 3 of 4 prostatic adenocarcinomas a strong positive reaction occurred with anti-Leu 4. All other antibodies tested were negative. Other tumours tested, including primary carcinomas of lung (2), kidney (3), stomach (1), colon (1), pancreas (1), breast (2), urinary bladder (1), esophagus (1), larynx (1) and malignant melanoma (2), were negative with all antibodies. This is, to our knowledge, the first report of cross reactivity between a monoclonal pan T-cell antibody and epithelium. This cross reaction may be related to a shared antigen between T-cells and prostate epithelial cells or, more likely, it represents reactivity with a shared epitope. Knowledge of this reaction will prevent possible misinterpretations in the evaluation of undifferentiated neoplasms.

Biosynthesis and metabolism of metallothionein in rat during perinatal development

Although high concentrations of zinc (Zn) and metallothionein (MT) have been detected in the livers of many newborn mammals, the factors affecting the biosynthesis and metabolism of MT are not yet clearly defined. In rat liver, MT levels rise sharply at the 18th day of gestation and continue to increase into the neonatal period. In late gestation, MT serves to bind Cu and Zn from the pre-existing pools of these metals, as well as to accumulate additional amounts of Zn. The high levels of Zn and MT are maintained for about two weeks in neonates and then decreased to adult levels at weaning. Perinatally, the Zn/MT ratio remains constant for several days, suggesting a carefully regulated process. Injection of ZnSO4 into newborn rats results in increased accumulation of Zn and induced synthesis of MT in liver, while injection of CdCl2 has no effect. When pregnant rats are fed with a Zn-D diet, there are marked reductions in the levels of both hepatic Zn and MT in neonates. Similar studies with copper and iron deficient diets have no effect on high hepatic MT and Zn levels in newborn rats. Immunohistochemical localization of MT using a specific antibody to MT shows a progressive increase in cytoplasmic MT with the appearance of nuclear MT by day 20 of gestation in fetal rat liver. The presence of MT in the nucleus of hepatocytes is maintained in neonates for several days and later MT is detected in the cytoplasm during postnatal development.