Presence of cutaneous interferon-alpha producing cells in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) patients have increased levels of interferon-alfa (IFN-alpha) in the circulation but a reduced number of functionally intact natural IFN-alpha producing cells (IPC) in peripheral blood. In search for tissue localisation of activated IPC, we investigated skin biopsies from SLE patients for the occurrence of such cells. Eleven SLE patients with inflammatory skin lesions and six healthy controls were biopsied.

Patients with systemic lupus erythematosus (SLE) have a circulating inducer of interferon-alpha (IFN-alpha) production acting on leucocytes resembling immature dendritic cells.

Patients with active SLE often have an ongoing production of IFN-alpha. We therefore searched for an endogenous IFN-alpha-inducing factor (IIF) in SLE patients and found that their sera frequently induced production of IFN-alpha in cultures of peripheral blood mononuclear cells (PBMC) from healthy blood donors, especially when the PBMC were costimulated with the cytokines IFN-alpha2b and granulocyte-macrophage colony-stimulating factor (GM-CSF). The phenotype of the IFN-alpha-producing cells (IPC) as determined by flow cytometry corresponded to that of the natural IPC, resembling immature dendritic cells.

Patients with systemic lupus erythematosus have reduced numbers of circulating natural interferon-alpha- producing cells.

Systemic lupus erythematosus (SLE) patients often have continuous production of interferon-alpha (IFN-alpha), but production of in vitro IFN-alpha by peripheral blood mononuclear cells (PBMC) may be varyingly reduced. We here report that IFN-alpha production induced by Herpes simplex virus (HSV) in PBMC resembling immature dendritic cells and designated natural IFN-alpha producing cells (NIPC), was much more affected than that induced by sendai virus (SV) in monocytes. At the cell level, the frequency of HSV-activated NIPC was reduced 70-fold, but residual NIPC produced normal amounts of IFN-alpha (1-2 U/cell).

Detection of serum interferon-alpha by dissociation-enhanced lanthanide fluoroimmunoassay. Studies of patients with acute viral and bacterial infections.

A sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) was evaluated for ability to detect interferon-alpha (IFN-alpha) in serum of patients with acute infectious disease of less than one week's duration and a fever of > 38 degrees C. None of 36 patients with confirmed or probable bacterial disease was IFN-alpha positive. In contrast, 13/26 patients with viral infections had detectable levels of IFN-alpha in serum, all clearly positive (> or = 10 U/ml).

The cell surface phenotype of human natural interferon-alpha producing cells as determined by flow cytometry.

The relationship between the so-called natural interferon-alpha (IFN-alpha) producing cell (IPC), stimulated to produce IFN-alpha by herpes simplex virus type 1 (HSV), and of dendritic cells (DC) in peripheral blood leucocytes was investigated. The simultaneous expression of cell surface antigens and intracellular IFN-alpha in the HSV-stimulated IPC (HSV-IPC) was examined by flow cytometry (FCM). The HSV-IPC were infrequent, < 0.

Stimulation of natural interferon-alpha/beta-producing cells by Staphylococcus aureus.

Human peripheral blood mononuclear cells (PBMCs) produced high levels of antiviral activity, as determined by bioassay, when stimulated by Staphylococcus aureus Cowan I (SAC) and E. coli. Specific immunoassays demonstrated the presence of both IFN-alpha and gamma and, for SAC, also low levels of IFN-beta.

Lectins inhibit the Aujeszky's disease virus-induced interferon-alpha production of porcine peripheral blood mononuclear cells.

The interaction between virus and peripheral blood mononuclear cells (PBMC) required to elicit the production of interferon-alpha (IFN-alpha) by the so-called natural interferon-producing cell is unknown. However, results from inhibition experiments suggest that viral glycoproteins are essential in this IFN induction process. We demonstrate here that cellular glycoproteins also appear to be involved in the initiation of IFN-alpha production.

Interferon system defects in malignant T-cells.

Deletions of chromosome 9p21-22 occur in acute lymphocytic leukemia (ALL), melanoma and glioma. With some exceptions, these deletions include the alpha- and beta-interferon (IFN) genes. In this study, the frequency of alpha- and beta-IFN gene deletions was investigated in 17 T-cell lines, and losses of IFN genes were related to other aspects of the IFN system.

Age-related increase of porcine natural interferon alpha producing cell frequency and of interferon yield per cell.

Porcine blood mononuclear cells (PBMC) were shown to secrete interferon alpha (IFN-alpha) after induction by a coronavirus, the transmissible gastroenteritis virus (TGEV). IFN-alpha producing cells, referred to as natural interferon alpha producing (NIP) cells, were detected by an ELISPOT assay using anti-porcine IFN-alpha monoclonal antibodies. The frequency of NIP cells among blood cells is low, at most 40-110 per 10(5) PBMC and each NIP cell was found to produce several units of IFN.

The leukocyte function-associated antigen-1 (LFA-1) is involved in the interferon-alpha response induced by herpes simplex virus in blood leukocytes.

The role of the leukocyte function-associated antigen-1 (LFA-1) family of integrins (beta 2 integrins) in the interferon-alpha (IFN-alpha) response was examined, using human peripheral blood mononuclear cells (PBMCs) stimulated in vitro by glutaraldehyde-fixed Herpes simplex virus-infected WISH amnion cells. Monoclonal antibodies (mAbs) to the beta 2 chain (CD18) and to the alpha chain of LFA-1 (CD11a) reduced the number of IFN-alpha-producing cells (IPCs) by 30-50%, but mAbs to CD11b or c caused no inhibition. The IB4 mAb to CD18 was inhibitory when added during the first 2 h of the IFN-alpha response, but did not alter its kinetic.

Interferon-alpha but not -beta genes require de novo protein synthesis for efficient expression in human monocytes.

Monocytes produce interferon-alpha (IFN)-alpha) and -beta when human peripheral blood mononuclear cells (PBMCs) are stimulated in vitro by Sendai virus (SV). We found that about 70% of the IFN-producing cells (IPCs) expressed both IFN-alpha and -beta mRNA; the rest expressed only IFN-beta mRNA. In the presence of the protein synthesis inhibitor cycloheximide (CHX), the frequency of IFN-alpha mRNA-containing cells, measured after 6h, was decreased by 85-90%.

The induction of interferon-alpha and interferon-beta mRNA in human natural interferon-producing blood leukocytes requires de novo protein synthesis.

The induction of interferon-alpha (IFN-alpha) and IFN-beta mRNA in natural IFN producing (NIP) cells in cultures of human peripheral blood mononuclear cells (PBMCs), stimulated by glutaraldehyde-fixed Herpes simplex virus type 1 (HSV)-infected WISH cells, was studied. The protein synthesis inhibitor cycloheximide (CHX) totally prevented the appearance of both IFN-alpha and IFN-beta mRNA, also in cultures supplemented with a conditioned medium (CM) assumed to contain soluble factors necessary for the IFN induction. However, when PBMCs were preincubated for 4 h in medium supplemented with fetal bovine serum (FBS) with or without addition of CM, the subsequent induction of IFN-alpha/beta mRNA became partially resistant to CHX.

Interferons and the colony-stimulating factors IL-3 and GM-CSF enhance the IFN-alpha response in human blood leucocytes induced by herpes simplex virus.

Human peripheral blood mononuclear cells (PBMC) were stimulated to produce interferon-alpha (IFN-alpha) by glutaraldehyde-fixed Herpes simplex virus type 1 (HSV)-infected WISH amnion cells in vitro. Different cytokines were included during the stimulation and tested for their ability to enhance the IFN-alpha response which occurs in the natural IFN-alpha producing (NIP) leucocytes. The total production of IFN-alpha and the numbers of IFN-alpha producing cells (IPCs) were increased by interleukin-3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF).

Filter spot-ELISA for the enumeration of interferon-alpha antibody-secreting cells.

A filter spot-ELISA was developed for the enumeration of interferon-alpha (IFN-alpha) antibody secretion by murine and human cells. Various human IFN-alpha subtypes were coated onto nitrocellulose membranes by means of broad specificity bovine antibodies. Membranes were blocked with milk proteins, and antibodies released by individual cells during a 3 h culture period were visualized as distinct spots using peroxidase-conjugated, species-specific anti-immunoglobulin antibodies and diaminobenzidine/hydrogen peroxide substrate solution.

Infrequent but efficient interferon-alpha-producing human mononuclear leukocytes induced by herpes simplex virus in vitro studied by immuno-plaque and limiting dilution assays.

Human blood mononuclear leukocytes (PBMCs) producing interferon-alpha (IFN-alpha) after stimulation by herpes simplex virus type 1 (HSV) in vitro were identified by a filter immuno-plaque assay. Individual IFN-alpha-producing cells (IPCs) yielded between 0.5 and 2 units IFN-alpha, sufficient to protect cultures of MDBK cells against a viral challenge.

Deficient herpes simplex virus-induced interferon-alpha production by blood leukocytes of preterm and term newborn infants.

The ability of peripheral blood mononuclear cells (PBMC) from newborn infants, gestational age 24-42 wk, to produce interferon-alpha (IFN-alpha) on the first day after birth was studied in vitro. Human amnion cells (WISH) coated with herpes simplex virus type I and fixed by glutaraldehyde were used as IFN-alpha inducers. Individual IFN-alpha producing cells (IPC) among PBMC were determined by an immunoplaque assay.

Determination of herpes simplex virus-induced alpha interferon-secreting human blood leucocytes by a filter immuno-plaque assay.

A filter immuno-plaque assay was developed which detects alpha interferon (INF-alpha)-secreting human peripheral blood leucocytes (PBL). Polyclonal anti-IFN-alpha antibodies were fixed to the nitrocellulose membrane bottoms of 96-well Millititer plates, which also contained monolayers of glutaraldehyde-fixed human WISH amnion cells infected by Herpes simplex virus type 1 (HSV). Such cells are potent IFN inducers and during a 16 h cocultivation with PBL, IFN-alpha was absorbed by the membrane-bound polyclonal antibodies around IFN-alpha-secreting cells.