Effect of interferon-alpha 1 from E. coli on some cell functions.

Interferon-alpha 1 from Escherichia coli transformed with a hybrid plasmid containing a human leukocyte complementary DNA insert, induces resistance to virus in appropriate target cells. It also shares the following properties with natural leukocyte interferon (IFN). (i) It enhances natural killing activity of human lymphocytes, (ii) it enhances antibody-dependent cell-mediated cytotoxicity, (iii) it suppresses antigen- and mitogen-induced leukocyte migration inhibition, (iv) it inhibits growth of IFN-sensitive Burkitt lymphoma cells. Since these activities are exhibited by a cloned protein species, they are due to IFN itself and not to other human proteins.

Detection of mutant-specific responses by macrophage migration inhibition reactions induced by wild-type and mutant polyoma viruses and polyoma virus-infected cells.

Macrophage migration inhibition responses of mice immunized with mutant polyoma viruses or with cells transformed and/or infected by them have been studied. The macrophage migration inhibition reaction revealed individual differences. In several cases, mice immunized with a mutant virus responded preferentially or exclusively to extracts of cells transformed or infected with the corresponding mutant. Moreover, in the macrophage migration inhibition test, mutant viruses were usually less immunogenic than were the corresponding transformed-infected cells.

Detection of a polyoma virus-induced tumor-associated membrane antigen in mouse cells by the macrophage migration inhibition test.

Soluble membrane fractions derived from polyoma tumor cells trigger lymphocytes, derived from polyoma-immunized animals, but not from nonimmunized controls, to release the lymphokine, macrophage migration-inhibitory factor. The reaction can be blocked by sera from polyoma-bearing animals. Absorption of these sera with polyoma cells, but not with nonpolyoma cell lines, abrogates this activity. These findings suggest that there is a polyoma virus-induced membrane component that can induce polyoma-specific macrophage migration inhibition.

Epstein-Barr virus-specific leukocyte migration inhibition reaction with tumor biopsy extracts: correlation with the presence of viral DNA.

The Epstein-Barr virus (EBV)-specific leukocyte migration inhibition (LMI) reaction was used to detect EBV antigens in human tumor biopsies in parallel with nuclei acid hybridization for EBV DNA. None of six EBV DNA-negative tumors gave any significant LMI reaction. Fourteen of 17 EBV DNA-positive tumors gave a significant difference between the migration of leukocytes from EBV-seropositive versus -seronegative donors. One tumor gave a borderline reaction. The two-LMI-negatives in this group had only a marginal EBV DNA content. It is suggested that the EBV-specific LMI test may be useful for detecting EBV genomes in tissue and tumor extracts.

T-cell response to B-cells and Epstein-Barr virus antigens in infectious mononucleosis.

After Epstein-Barr virus (EBV) infection in vivo, B-cells with latent virus infection persist indefinitely through life. These cells grow in vitro on explanation and can be established as immortal B-cell lines. To reconcile the unlimited growth potential in vitro with the maintenance of a low proportion of B-cells infected by EBV in vivo, a strict in vivo control mechanism has to be postulated. Certain aspects of this control are apparent when the primary infection is followed by infectious mononucleosis. This is characterized by lymphocytosis and the presence of activated T-cells. The T-cell proliferation is probably the manifestation of the immune response against EBV antigens. However, the reaction of T-cells upon encounter of B-blasts is also likely to contribute to the events. At present, it is difficult to detect an EBV-specific component in the action of the T-cells in the acute phase of mononucleosis exerted on B-cells. However, for the clinical course of the disease the activation of T-cells is important. The activated T-cells may control and also eliminate the B-cells infected by EBV. In addition to the immunity which develops during the disease, th immunoregulatory mechanism is likely to have a role in the inhibition of B-cell proliferation.

Immunological characterization of Hodgkin's and non-Hodgkin's lymphoma patients with high antibody titers against Epstein-Barr virus-associated antigens.

We have studied nine Hodgkin's lymphoma (HD) and ten non-Hodgkin's lymphoma (NHL) patients with extraordinarily high anti-viral capsid antigen (VCA) titers (greater than 5120). Controls were 13 HD and 23 NHL patients with anti-VCA titers between 40 and 2560. High anti-VCA titers were present in NHL patients at the time of diagnosis or within 16 months, whereas the rise of anti-VCA titers in HD patients appeared to be a late event during the clinical course of the disease (mean time from diagnosis, 68 months). In particular, we have asked whether the exceptionally high anti-Epstein-Barr virus (EBV) titers in some HD and NHL patients can be correlated to some of the EBV-specific and -nonspecific parameters of cell-mediated immunity. The battery of non-EBV-specific immunological tests included the assessment of natural killer cell activity and the analysis of T-lymphocyte subclasses according to surface markers, together with spontaneous and mitogen-induced DNA synthesis and their helper or suppressor activity on PWM-generated immunoglobulin synthesis. Outgrowth inhibition (Ol) and leukocyte migration inhibition were used to assess EBV-specific cell-mediated immunity. The majority of the high-titer HD and NHL patients showed a drastically reduced OKT4:OKT8 ratio in their peripheral lymphocyte population. Low-titer HD and NHL patients showed no such reduction. There was no strict correlation between the number of OKT8-positive cells and suppressor activity in the functional PWM-induced immunoglobulin production test. Part of the high-titer HD patients showed defective cellular responses in the outgrowth inhibition test, directed against the proliferation of EBV-transformed (EBV-determined nuclear antigen-positive) cells. Some of them showed also a deficient leukocyte migration inhibition response to EBV-determined nuclear antigen but, interestingly, not to early antigen-VCA. In the NHL group, only one of the high-titer patients showed a similar defect. None of the low-titer HD and NHL patients showed such defects.

Cell-mediated immune reactions in three patients with malignant lymphoproliferative diseases in remission and abnormally high Epstein-Barr virus antibody titers.

Two patients with Hodgkin's disease in remission and one chronic lymphatic leukemia patient with extraordinarily high anti-Epstein-Barr virus (EBV) (viral capsid antigen) antibody titers (greater than 10,000) were selected to study a spectrum of cell-mediated immune responses, including natural killer, interferon-boosted killer, antibody-dependent lymphocytotoxicity, and T-cell-mediated reactions. The purpose was to compare these reactions in patients with immunosuppression and a high EBV load who can hold their EBV-carrying cells under control with the corresponding reactions in patients with EBV-carrying lymphoproliferative disease. In contrast to the latter group, the three patients of the present study showed a less profound and less general suppression of the immune responses. Multiple effector mechanisms probably safeguard against the proliferation of EBV-transformed B-cells. Clinically manifest EBV-carrying lymphoproliferative disease occurs only in very severe immunodeficiencies effecting multiple effectors.

Cellular immune defects to Epstein-Barr virus-determined antigens in young males.

Three males with the X-linked lymphoproliferative syndrome (XLP) with hypo- or agammaglobulinemia following Epstein-Barr virus (EBV) infection and two males with the chronic mononucleosis syndrome were investigated for immune responses to EBV-determined antigens. Males with XLP showed profound cellular immune defects. Markedly diminished responses of natural killer cell and interferon-activated killer cell activities and impaired leukocyte migration inhibition responses to phytohemagglutinin were determined in patients with XLP. The two patients with chronic mononucleosis showed less severe defects. All patients showed partial or complete impairment of their EBV-specific immune responses as measured by leukocyte migration inhibition. EBV-specific antibodies were markedly diminished against EBV-associated nuclear antigen, early antigen, and viral capsid antigen in males with XLP. In contrast, patients with chronic mononucleosis had elevated antibodies to most EBV-specific antigens. Individuals with life-threatening EBV-induced lymphoproliferative disorders may exhibit multiple defective immune mechanisms against the virus.

An EBV genome carrying pre-B cell leukemia in a homosexual man with characteristic karyotype and impaired EBV-specific immunity.

A Burkitt-like lymphoma/leukemia confined to bone marrow was detected in a human T cell leukemia virus (HTLV)-III/LAV- and Epstein-Barr virus (EBV)-seropositive homosexual man. The tumor cells were EBNA-positive and contained at least 22 EBV genomes per cell. They were totally immunoglobin negative, but showed other markers for B cells detected with monoclonal antibodies. The patient had an impaired cellular immunity to EBV antigens and EBV-infected cells at diagnosis, but these reactions normalized during treatment. Cell clones derived from the bone marrow tumor in vitro also carried EBV and had six different marker chromosomes, including the typical 14q+ chromosome and a t(8 - ;8), which resulted in trisomy for the largest part of 8q. Partial trisomy for 12q was also observed. The patient completed six courses of combination chemotherapy and remains in excellent health after 34 months of follow-up.

Immunomodulatory effect of synthetic peptides corresponding to sequences within the CH2 and CH3 domain of human IgG1.

The Fc region of IgG is known to be the source of small peptides possessing immunomodulatory function. Results are summarized showing the effect of synthetic peptides composed of surface exposed residues of C gamma 2 or C gamma 3 domains on different steps of human B lymphocyte activation cycle. Both the CH2 (289Thr-301Arg) and CH3 (407Tyr-416Arg) peptides as well as the whole Fc fragment enhanced the IgM synthesis of PWM or PMA + CaI activated lymphocytes. This effect was exerted at the early phase of B cell activation. The incubation of separated resting B cells with Fc fragments or CH2 peptides resulted in increase of cell volume and in expression of HLA-DR antigen. On the other hand, LIF production was induced both by CH2 and CH3 peptides. It was also shown that Fc peptides induce IL-1 release from monocytes. The results suggest that the CH2 and CH3 domain peptides exert their effect partly directly, by activating resting B cells, rendering the cells more susceptible to other stimuli; and moreover, by enhancing the humoral response by triggering the release of IL-1.

Use of cryopreserved lymphocytes for the indirect leukocyte migration inhibition assay.

Production of leukocyte migration inhibitory factor (LIF) by fresh and cryopreserved lymphocytes from the same donors was detected by indirect leukocyte migration inhibition (LMI) assay. The same results were obtained when fresh and frozen lymphocytes were tested in parallel. This indicates that cryopreservation does not impair the ability of lymphocytes to produce LIF.

Antibodies in human sera against the Epstein-Barr virus encoded latent membrane protein (LMP).

Antibodies reactive with the Epstein-Barr (EBV)-encoded latent membrane protein, LMP, were detected in human sera. Membrane fractions of the EBV-carrying Raji cells and a fusion protein (LMFP), that represents the carboxy part of LMP, were used as antigens. These were assayed by the reduction of the leukocyte migration inhibition (LMI) reaction. Reactivity with LMFP was detected in 10 of 14 sera from patients with Burkitt's lymphoma (BL) and in 3 of 23 sera from healthy EBV-seropositive individuals. The antibody levels were higher in the BL sera. Since the tumor cells do not express LMP, this may be due to the high virus load in the patients.

Leukocyte migration inhibitory factor production by activated lymphocytes representing immunological memory or virus-receptor interaction: response of T cell subsets to Epstein-Barr virus nuclear antigen, response of B cells to UV inactivated Epstein-Barr virus.

Both T and B lymphocytes are known to produce leukocyte migration inhibitory factor (LIF) after appropriate activation. We showed that EBV nuclear antigen (EBNA) triggered T cells for LIF production in an immunologically specific way: only T cells of seropositive individuals responded. Both Fc receptor positive and negative T cells produced LIF, and the presence of macrophages was necessary. The virus itself activated B cells independently of the serological status of the donors, thus the function was not based on immunological memory. This phenomenon was independent of the transforming capacity of the virus, because UV-inactivated virus also elicited LIF production by B lymphocytes. This triggering seems to be the consequence of the virus-receptor interaction on the cell surface.

Nitric oxide and ATP co-mediate the NANC relaxant response in the guinea-pig taenia caeci.

The effect of the nitric oxide synthase inhibitor N(G)-nitro-L-arginine (L-NOARG; 100 microM) and the P2 purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 50 microM) was investigated on the non-adrenergic, non-cholinergic (NANC) relaxant response of the guinea-pig isolated taenia caeci to electrical field stimulation at 1 or 10 Hz, under isotonic recording conditions. Either drug alone caused an about 50% inhibition, while combining the two drugs nearly abolished the response at both frequencies. The inhibitory effect of L-NOARG (100 microM) was partly reversed by L-arginine (30 mM). PPADS, but not L-NOARG, inhibited the relaxant effect of exogenous ATP, but not that of the nitric oxide donor sodium nitroprusside. It is concluded that both nitric oxide and ATP are involved in the mediation of NANC relaxation in the taenia caeci, in an apparently additive manner.

Inhibitory effect of PACAP(6-38) on relaxations induced by PACAP, VIP and non-adrenergic, non-cholinergic nerve stimulation in the guinea-pig taenia caeci.

The effect of the pituitary adenylate cyclase activating polypeptide (PACAP) receptor antagonist PACAP(6-38) on the relaxant response to exogenous PACAP, vasoactive intestinal polypeptide (VIP) and nonadrenergic, non-cholinergic (NANC) nerve stimulation was tested in the guinea-pig taenia caeci, in the presence of atropine (10(-6) M) and guanethidine (3x10(-6) M). PACAP(6-38) (3x10(-6) M) strongly inhibited sub-maximal relaxations evoked by exogenous PACAP (1-3x 10(-8) M) or VIP (10(-8) M), but not those due to isoprenaline (4-8x10(-8) M) or ATP (10(-6) M). PACAP(6-38) caused a small but significant (approximately 20%) inhibition of the NANC relaxation due to electrical field stimulation (1 Hz or 10 Hz for 20 s). At these frequencies PACAP(6-38) caused no inhibition of the NANC relaxation in the presence of the P2 purinoceptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS; 5x10(-5) M), or PPADS plus the NO-synthase blocker NG-nitro-L-arginine (L-NOARG; 10(-4) M); in preparations pretreated with L-NOARG (10(-4) M) alone PACAP(6-38) retained its inhibitory effect. The PPADS- and L-NOARG-resistant NANC relaxation with 10 Hz electrical stimulation was blocked by apamin (10(-7) M); it was not significantly modified by the tachykinin receptor antagonist spantide (10(-5) M). Tachyphylaxis to PACAP(1-27) (10(-7) M for 10 min) strongly inhibited the relaxation due to PACAP(1-38) (1-3x10(-8) M) and reduced electrical stimulation-evoked relaxations by half. The putative VIP antagonist VIP(10-28) (10(-5) M) failed to significantly reduce the relaxant action of exogenous VIP (1-3x10(-8) M). Relaxation induced by PACAP(1-38) (1-2x10(-8) M) was not influenced by a mixture of PPADS (5x10(-5) M) and L-NOARG (10(-4) M). It is concluded that: (a) PACAP(6-38) is a VIP/PACAP antagonist in the guinea-pig taenia caeci; (b) a release of a VIP/PACAP-like substance from enteric nerves is involved in the NANC relaxation in this preparation, but its contribution is relatively small and seems to depend on the functional integrity of the PPADS-sensitive inhibitory mechanism; (c) the PPADS- plus L-NOARG-resistant NANC relaxation probably involves apamin-sensitive K+ channels.

The bifactor model of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS)--an alternative measurement model of burnout.

The purpose of the present study was to examine the construct validity of the Hungarian language version of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS). A sample of 653 healthcare professionals (420 physicians and 233 nurses and nursing assistants) completed the MBI-HSS. A series of confirmatory factor analyses showed that a hierarchical bifactor model including a global burnout factor and three specific factors of emotional exhaustion, depersonalization and reduced personal accomplishment had the closest fit to the data, compared with an alternative second-order three-factor hierarchical model as well as to non-hierarchical one-factor, two-factor, three-factor, four-factor and five-factor models. However, only the global burnout factor and the specific personal accomplishment factor explained a considerable unique proportion of variance in observed scores. Our study confirms the validity of the MBI-HSS and suggests an alternative structural model, which may contribute to further understanding of the burnout construct.