Activation of measles virus from silently infected human lymphocytes.

Lymphocytes were incubated with measles virus for 4 days in the absence of a lymphocyte stimulating agent. Such nonstimulated lymphocytes, infected with measles virus, did not express the virus antigens that are detectable by cytotoxic antibodies. Approximately 1 out of 5,000, or even fewer, of such lymphocytes produced virus as demonstrated by the infectious center assay; in the supernate only 10--100 infectious viruses per milliliter were detected. No virus structures could be observed by means of an electron microscope. However, such lymphocytes showed no reaction to phytohemagglutinin (PHA) in terms of DNA synthesis in a subsequent culture in the presence of antibodies against measles to prevent spreading of the infection to other cells. Although stimulation by PHA did not result in a significant increase in [3H]thymidine incorporation, measles virus was activated; 32 h after the addition of PHA nearly 80% of the cells were killed by measles virus antibodies and complement. The number of virus-producing cells increased to approximately 1 in 300 or more, and at 72 h the virus titer in the supernate had risen to 10(6) infectious particles per ml. This reactivation of measles virus was still obtained when PHA was added as late as 8 or more days after the initial infection.

Clonal analysis of functionally distinct human CD4+ T cell subsets.

A large number of CD4+ T cell clones, obtained from peripheral blood T lymphocytes by direct limiting dilution, allowed us to address the question whether functional heterogeneity exists within the human CD4+ T cell subset. Cytotoxic capacity of cloned T cells was analyzed with the use of anti-CD3 antibodies and target cells bearing FcR for murine IgG. 6 of 12 CD4+ clones obtained were able to lyse Daudi or P815 cells in the presence of anti-CD3 antibodies. The remaining six CD4+ T cell clones tested did not display anti-CD3-mediated cytotoxic activity and did not acquire this cytotoxic capacity during a culture period of 20 wk. In the absence of anti-CD3 mAb, no lytic activity against Daudi, P815, and K562 target cells was observed under normal culture conditions. Phenotypic analysis of these two distinct types of CD4+ T cells did not reveal differences with regard to reactivity with CDw29 (4B4) and CD45R (2H4) mAbs that have been described to recognize antigens associated with helper suppressor/inducer (respectively) CD4+ cells. The CD4+ clones without anti-CD3-mediated cytotoxic activities (Th2) consistently showed a high expression level of CD28 antigens, whereas the cytotoxic clones (Th1) expressed low amounts of CD28. Th1 CD4+ clones did produce IL-2, IFN-gamma, and TNF-alpha/beta, whereas the Th2 T cell clones produced minimal amounts of IL-2 and only low levels of INF-gamma and TNF-alpha/beta in response to anti-CD3 mAbs and PMA. Although not all CD4+ clones did release IL-4, there was no correlation with cytotoxic activity. Moreover, as compared with the Th1 CD4+ clones, Th2 CD4+ T cell clones proliferated moderately in response to immobilized anti-CD3 mAbs. However, proliferation reached the level of the cytotoxic clones when anti-CD28 mABs were present during culture. Both CD4+ subsets provided help for B cell differentiation upon stimulation with anti-CD3 mAbs. Our data suggest that the human CD4+ subset, in analogy to the murine system, comprises two functionally distinct T cell subpopulations, both of which are able to exert helper activity for polyclonal B cell differentiation, but which differ in cytotoxic capacity, lymphokine production, and requirements for proliferation. A function for these two types of T cells in the immune response is discussed.

IFN-beta modulates specific T cell responses in vitro but does not affect Experimental Autoimmune Encephalomyelitis in the SJL mouse.

In this study, mouse recombinant IFN-beta was shown to favor PLP139-151-specific Th2 responses in vitro, by inhibiting IFN-gamma production and stimulating IL-4 and IL-10 production. IFN-beta (5000 U/day) failed to prevent the development or severity of EAE induced with PLP139-151. Whereas efficacy of IL-10 was found in the B. pertussis assisted but not in the pertussigen-assisted EAE model, both models appeared insensitive to IFN-beta. Also the combination of (suboptimal) IL-10 and IFN-beta appeared ineffective in inhibiting disease. However, the PLP139-151-specific IL-10 production by T cells from these mice appeared significantly more sensitive to the stimulatory effect of IFN-beta in vitro. It is concluded that despite its Th2 promoting effects, IFN-beta is not effective in inhibiting EAE in this study.

Elevated levels of a soluble form of the T cell activation antigen CD27 in cerebrospinal fluid of multiple sclerosis patients.

The expression of the T cell membrane molecule CD27--a molecule that has recently been shown to belong to the nerve growth factor receptor superfamily--is strongly increased after activation of T lymphocytes via the T cell receptor/CD3 complex. In addition, activated cells release a 28-32 kDa soluble form of CD27 in their supernatant which can also be detected in serum and urine of healthy individuals. In this study we show that levels of soluble (s) CD27 are significantly elevated in cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients and of patients and of suffering from other inflammatory neurological diseases (OIND), whereas increased levels of sCD25 (soluble interleukin-2 receptor) were only found in CSF of patients with OIND. In MS patients, a significant correlation was found between CSF sCD27 titer and IgG index.

Minor myelin proteins can be major targets for peripheral blood T cells from both multiple sclerosis patients and healthy subjects.

T cell recognition of myelin is likely to play a role in the pathogenesis of multiple sclerosis. Predominant protein components of myelin, myelin basic protein (MBP) and proteolipid protein (PLP), have been considered as possibly relevant autoantigens, especially since both proteins are encephalitogenic in various laboratory animals. It has remained unclear, however, to what extent the numerous minor proteins contained in myelin may serve as targets for human T cell responses to myelin. In this study, the abilities of several minor myelin proteins to trigger proliferative responses of human peripheral blood T cells were compared to that of MBP. By using a water soluble collection of myelin proteins as an antigen, including MBP as the major component, short-term T cell lines were generated. Proliferative responses were determined against the various proteins after their fractionation by HPLC. Short-term T cell lines from both multiple sclerosis patients and healthy control subjects displayed significant responses to several minor myelin proteins but failed to respond to MBP. Only the use of purified MBP as trigger antigen allowed the selective expansion of MBP-specific T cell lines. These findings indicate that minor myelin proteins may act as relevant targets for autoreactive human T cells.

Influenza virus changes cell-surface glycoproteins including major histocompatibility complex determinants on lymphocytes.

The effect of influenza virus infection on the expression of major histocompatibility complex (MHC) antigens was investigated. Infection with influenza virus resulted in an increase of the binding of anti-MHC class I and class II antibodies to resting T cells. The binding of anti-MHC class II antibodies to activated T cells was increased approximately threefold. The binding of anti-MHC class I and class II antibodies to Epstein-Barr virus-transformed B cells appeared unaffected after influenza virus infection. Recombinant human interferon-alpha and/or -gamma added to T cells did not enhance the binding of anti-MHC antibodies. Biochemical analysis revealed no increase in the amount of class I and class II antigens as a consequence of viral infection, but a marked decrease in sialic acid content was found, most probably caused by the viral neuraminidase. Pulse-chase experiments suggest that the viral neuraminidase can catalyze the removal of sialic acids both en route to and at the cell surface. The absence of sialic acid residues can explain the increased binding of anti-MHC antibodies, because neuraminidase (clostridium perfringens) treatment of T and Epstein-Barr virus-transformed B cells resulted in a shift in both isoelectric point and antibody binding similar to that observed after influenza virus infection.

Subtypes of HLA-B27 detected by cytotoxic T lymphocytes and their role in self-recognition.

In the present study cytotoxic T lymphocytes were generated in MLC of lymphocytes from two unrelated HLA-A, B, C-identical, B27-positive, but D/DR-different, individuals. These CTL were shown to detect subtypes of HLA-B27. CTL specific for influenza virus lysed infected target cells matched for HLA-B27 only when they shared the same subtype. This indicates that the two subtypes of HLA-B27 detected by CTL function also as distinct elements in a self-restricted CTL response. Both subtypes were found among patients with ankylosing spondylitis.

Subacute sclerosing panencephalitis in The Netherlands--1976-1990.

Since 1976, when general immunization against measles was introduced in the Netherlands, all new cases of subacute sclerosing panencephalitis (SSPE) were registered and detailed data about immunization, epidemiology and disease progression were collected on them. Up to 1991, 99 new patients have been registered of which 81 were born in this country and 18 elsewhere. From 1981 onwards, the incidence of SSPE among those born in the Netherlands decreased gradually from 13 cases per year to one case per year. This decrease is attributed to the large scale of immunization against measles. Three SSPE patients had been immunized against measles, all of them without a history of clinical measles. Epidemiology and risk factors of SSPE did not differ from those reported in other countries. An exceptional cluster of four patients in one town, who had measles in the same year, is reported. Progression of SSPE appeared to be age related. A total of 28 patients was treated with Inosiplex; no significant effect on survival in stage 3 of the disease was found.

Physico-chemical and immunological properties of acid alpha-glucosidase from various human tissues in relation to glycogenosis type II (Pompe's disease).

The physico-chemical and immunological properties of acid alpha-glucosidase from various human tissues have been studied. Heat stability of acid alpha-glucosidase from heart, liver and skeletal muscle is identical, but for kidney some different results are obtained. Identical isoelectrofocussing patterns are found for heart, liver and skeletal muscle. Furthermore, the effect of antiserum against human liver acid alpha-glucosidase on the activity of acid alpha-glucosidase from various tissues is studied. The results are discussed in relation to glycogenosis type II (Pompe's disease).

Cytotoxic T-cell response to influenza A subunit vaccine in patients with type 1 diabetes mellitus.

The cytotoxic T-cell and humoral immune response to a commercially available influenza A-H1N1 subunit vaccine in 14 patients with type 1 diabetes mellitus was compared with the response in 13 healthy volunteers. Cytotoxic T-cell response to vaccination was poor in both patients and controls. At a calculated 50: 1 effector-target cell ratio, however, significantly more controls than patients showed an increase of over 5% cytotoxic T-cell mediated lysis after vaccination (P less than 0.05). In patients the cytotoxic T-cell response decreased with higher percentages of glycosylated haemoglobin (regression coefficient not equal to 0 with P less than 0.05). No significant difference was found between diabetic patients and control subjects with respect to antibody response after vaccination. Implications for vaccination strategy are discussed.

Asymmetry in the recognition of HLA-A3 molecules by virus-specific cytotoxic T cells.

Cytotoxic T cells specific for influenza virus A/HK or Epstein-Barr virus were used to study the heterogeneity of the HLA-A3 molecule. Variability of the recognition of HLA-A3 in both systems was observed. The hierarchy was both effector cell and target cell specific. An extreme example of the hierarchy of HLA-A3 recognition is the following. Virus-specific cytotoxic T lymphocytes of a given donor were found to recognize all HLA-A3-matched target cells, including target cells of a donor from whom the virus-specific effector cells did not recognize target cells of that given donor: Donor A recognizes target B but donor B does not recognize target A. Both will recognize a third HLA-A3-matched target cell C. Cold target inhibition studies confirmed that the recognition of target cell B by effector cell A involved the recognition of only HLA-A3. Examples of such asymmetric recognition were found in both influenza A and Epstein-Barr virus-specific cytotoxic T-lymphocyte responses but not one combination was asymmetric in both systems. This suggests that influenza virus A/HK-specific cytotoxic T lymphocytes recognize other HLA-A3 histotopes than do Epstein-Barr virus-specific cytotoxic T lymphocytes.

Personality correlates of study difficulty and academic performance in university students. I. The Middlesex Hospital Questionnaire and Dynamic Personality Inventory.

The personality correlates of study difficulty and academic performance in university students have been measured in terms of psychiatric symptomatology and premorbid characteristics. The UCLSQ, MHQ and DPI were administered to two groups of male and female students presenting at an health centre: one (n = 72) of patients seeking psychological help, the other (n = 73) a control group. Significant differences between the two groups were formed on the MHQ, confirming previous results; and these were supplemented by differences on the DPI. Motivational and psychoneurotic components of study difficulty were significantly related to MHQ scores in both groups. DPI scores were more closely related to study difficulty in the patients than controls; and served particularly to characterize their sylbism and work satisfaction. The DPI added to the picture of a subgroup of students observed both in an earlier and the present study: academically successful patients scoring high on phobic anxiety.

Personality correlates of study difficulty and academic performance in university students. II. Conscience and self-esteem.

Scales measuring self-esteem and conscience have been included in a further study of work-related symptoms in students. Two groups were tested: a group of patients attending the UCL Student Health Centre for psychological reasons, and a group of normal controls. Conscience and self-esteem were inversely related to one another. Both tests were reliable and differentiated between the groups. The patients tend to have low self-esteem, high conscience, and to score higher than controls both on neurotic symptoms as such as measured by a personality inventory (MHQ) and as assessed on work-related symptoms measured by our study difficulty questionnaire (UCLSQ). In terms of academic performance, an interesting subgroup of students was delineated who are rated highly by their tutors but who appear subjectively troubled with phobic anxiety, low self-esteem and a harsh conscience structure. The conscience and self-esteem scales, in view of their brevity, acceptable reliability, and in terms of the relationships discussed in this paper, will be retained for further research.