Thermal inactivation of human immunodeficiency virus in lyophilised blood products evaluated by ID50 titrations

Inactivation of human immunodeficiency virus (HIV) in lyophilised small pool cryoprecipitate, factor VIII concentrate, prothrombin complex and C1-esterase inhibitor concentrate by prolonged heat treatment (72 h, 60 degrees C) was studied. Plasma products, inoculated prior to lyophilisation, had infectious titres ranging from 10(7) to 10(10.5). Residual infectivity (TCID50) was assessed by multiple titrations on H9 cells in a macro system and subsequent detection of virus replication by determining reverse transcriptase activity. Kinetics of inactivation showed a biphasic pattern: during the first 8 h a variable TCID50 reduction up to 10(4.3) was observed, followed by an additional loss of 10(1)-10(2.7) during the next 64 h. Heat treatment for 72 h resulted in a mean TCID50 reduction of 10(5). It is concluded that prolonged heat treatment may lead to the adequate prevention of HIV transmission by lyophilised plasma products.

The role of IL-2 and T4+ cells in the generation of human influenza virus-specific CTL activity

Stimulation of human peripheral blood lymphocytes (PBL) with influenza A virus leads to the generation of virus-specific cytotoxic T lymphocyte (CTL) activity as well as natural killer (NK)-like activity. In this study, we show that exogenous IL-2 augments the in vitro generation of virus-specific CTL activity, only when added some days after the initiation of the culture. Apparently, the endogenously produced IL-2 can be a limiting factor in the in vitro generation of CTL activity. The increase of influenza virus-specific CTL activity after addition of exogenous IL-2 does not affect the restriction pattern of the CTL response. So, the preferential use of certain HLA antigens as restriction elements is not due to a limiting amount of endogenously produced IL-2. Depletion of T4+ cells completely abrogates the generation of virus-specific CTL activity. Addition of exogenous IL-2 to T4+-cell-depleted cultures fully restores the generation of HLA-restricted virus-specific CTL activity. We conclude that in the in vitro generation of virus-specific CTL activity in bulk cultures of human PBL the sole function of T4+ cells in human virus-specific CTL generation is the production of IL-2, no cognitive cell interaction of T8+ CTL precursors with T4+ cells is required, and in bulk cultures T8+ cells themselves are not able to produce sufficient amounts of IL-2 to ascertain the maturation of virus-specific CTL precursors into cytolytic T cells. Finally, we show that exogenous IL-2 also has a stimulatory effect on the NK-like or lymphokine-activated killer activity, which is always concomitantly induced in virus-specific CTL generation cultures, but has no influence on the levels of IFN produced in such cultures.

IL-2- and IFN gamma-enhanced natural cytotoxic activity: analysis of the role of different lymphoid subsets and implications for activation routes

To elucidate the immunoregulatory mechanisms by which human recombinant interleukin 2 (r.IL-2) and human recombinant interferon (IFN)-gamma influence natural cytotoxic activity of human peripheral blood lymphocytes (PBL), experiments were performed in which we studied: the kinetics of augmentation of natural cytotoxic activity by IL-2 and IFN-gamma; the phenotypes of the natural cytotoxic precursor cells acted upon by IL-2 and IFN-gamma; the role of IL-2-induced IFN-gamma in the natural cytotoxic activity enhancing effects of IL-2 and (d) the surface phenotypes of the natural cytotoxic cells activated by IL-2 or IFN-gamma. Three phenotypical distinct precursor cells can be identified. The phenotypes of the precursor cells sensitive to r.IFN-gamma are T3-, Leu 7+or-, FcR-gamma+. The phenotypes of the precursor cells sensitive to r.IL-2 are T3-, Leu 7-, FcR-gamma+or-. It appears that during prolonged culture relatively more of the FcR-gamma- precursor cells acquire natural cytotoxic activity upon stimulation with r.IL-2. Antibodies to IFN-gamma, known to neutralize both recombinant and natural IFN-gamma, completely inhibited the IFN-gamma-induced augmentation of natural cytotoxic activity but only slightly affected the IL-2-mediated augmentation. This indicates that only part of the augmenting effect of r.IL-2 is mediated through IL-2-induced IFN-gamma. This implies that r.IL-2 augments natural cytotoxic activity predominantly through an IFN-gamma-independent pathway. The phenotype of the effector cells expressing natural cytotoxic activity after a 4-day culture period with IL-2 or IFN-gamma was analyzed by depletion experiments. Virtually all the cells that exerted the IFN-gamma-enhanced natural cytotoxic activity are FcR-gamma+, whereas a portion of the cells that exerted the IFN-gamma-enhanced natural cytotoxic activity are FCR-gamma-. Both natural killer cells and lymphokine-activated killer cells contribute to natural cytotoxic activity. The relative contributions of both activities to the natural cytotoxic activity augmented by IL-2, respectively, IFN-gamma, is 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.

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.

Killing of measles virus-infected cells by human cytotoxic T cells

Lymphocytes from normal individuals were tested for the capacity to generate measles virus-specific cytotoxic T-cell responses after in vitro stimulation with measles virus. Approximately 12% (5 of 40) of the normal adults tested produced significant cytotoxic responses. The cytotoxic response was measles virus specific both at the level of stimulation and at the effector level. Studies of the specificity of cytotoxic effectors from five normal donors by direct lysis or cold target inhibition or both indicated that most, if not all, of the virus-specific activity was self-specific. A detailed analysis of one donor (W6) indicated that measles-specific cytotoxicity was largely HLA-A and -B restricted; unexplained cross-reactive lysis was observed with some targets, but this lysis appeared to be HLA related, since all of the targets expressed HLA-B12. An analysis of the cellular requirements for the production of measles-immune cytotoxic T lymphocytes demonstrated that T cells and macrophages (depleted of natural killer and K cells) were sufficient for the generation of killer cells. Most of the cytotoxic effector activity was mediated by OKT3+ OKT4- OKT8+ cells.

Cytotoxic T lymphocyte responses against alloantigens exhibit preferential effector cell activity for H-2K or H-2D region products similar to that for H-2 restricted responses

The present study was designed to investigate the patterns of allogeneic cytotoxic T cell responses against H-2K and H-2D region products. B10.D2 anti-B10.A(2R) effector cells lysed K-end matched target cells approximately 5 times more efficiently than D-end matched target cells. In contrast, C57BL/10 anti-B10.A effector cells killed K-end or D-end matched target cells equally well, whereas C57BL/10 anti-B10.D2 CTL exhibited a slight preference for D-end matched target cells. These results demonstrate that whole H-2 disparate stimulating populations do not necessarily induce equivalent h-2K and H-2D region-specific CTL responses. The strength of the cytotoxic responses was found to correlate with the number of known serologically detectable specificities shared between the stimulating and target cell populations. The similarities between these allogeneic and MHC-restricted CTL response patterns (which are under Ir-like control) raise the possibility that this regulation reflects the number of K or D region self-antigens that can be recognized in association with a foreign antigenic determinant and suggests that allogeneic responses to major histocompatibility antigens are also self-restricted by MHC gene products. The possibility is considered that such Ir-like control is also a reflection of the amounts of H-2K and H-2D products shed from the cell surface.

Cytotoxic T lymphocyte responses against alloantigens exhibit preferential effector cell activity for H-2K or H-2D region products similar to that for H-2 restricted responses

The present study was designed to investigate the patterns of allogeneic cytotoxic T cell responses against H-2K and H-2D region products. B10.D2 anti-B10.A(2R) effector cells lysed K-end matched target cells approximately 5 times more efficiently than D-end matched target cells. In contrast, C57BL/10 anti-B10.A effector cells killed K-end or D-end matched target cells equally well, whereas C57BL/10 anti-B10.D2 CTL exhibited a slight preference for D-end matched target cells. These results demonstrate that whole H-2 disparate stimulating populations do not necessarily induce equivalent h-2K and H-2D region-specific CTL responses. The strength of the cytotoxic responses was found to correlate with the number of known serologically detectable specificities shared between the stimulating and target cell populations. The similarities between these allogeneic and MHC-restricted CTL response patterns (which are under Ir-like control) raise the possibility that this regulation reflects the number of K or D region self-antigens that can be recognized in association with a foreign antigenic determinant and suggests that allogeneic responses to major histocompatibility antigens are also self-restricted by MHC gene products. The possibility is considered that such Ir-like control is also a reflection of the amounts of H-2K and H-2D products shed from the cell surface.

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.

Sex differences, personality and study difficulty in university students

A study difficulty inventory and three sets of personality scales were administered to 145 students attending a university health centre. Motivational and psychoneurotic components of study difficulty were identified, which were differentially related in male and female students to basic personality characteristics and to psychiatric symptomatology. Syllabus-boundness emerged as more salient in the female students, and self-esteem in the males. Poor academic performance was found to be associated with distinctive personality profiles in the two sexes. Both intra-personality and social–psychological interactional factors appear to underlie the pattern of results.

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.

Further observation on study difficulty in university students including 'syllabus-boundess'

The UCLS questionnaire, in a form modified to include a measure of syllabus-boundness, and a questionnaire to measure psychiatric symptomatology (the MHQ) were administered to two groups of students, one seeking help for emotional problems, the other a control group. Groups were compared on tests, test findings were inter-correlated, and scores were related to academic success. The UCLSQ is confirmed as a reliable research instrument. Principal component analysis again indicates a separation of psychoneurotic and motivational components of study difficulty. Syllabus-boundness ('Sylbism') emerges as a relatively independent trait, with a significant negative relationship to work satisfaction in both groups. MHQ scores again show a positive correlation between phobic anxiety and academic attainment for patients.

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).

Tubuloreticular structures in human lymphoid cell lines. A cell biological study

Human lymphoid cell lines were studied as an experimental model for the spontaneous or induced occurrence of tuburloreticular structures (TRS). It was possible to induce TRS after culturing the EB-3 cell line with 20 mug/ml bromodeoxyuridine (BrUdR) during 96 h. Starvation, culturing at lower temperature (32 degrees) or inhibition of DNA synthesis did not give rise to the production of TRS. The response to BrUdR could be blocked with 60 mug/ml thymidine but not with 60 mug/ml deoxycytidine. The addition of 5 mug/ml cytarabine or the removal of BrUdR at different times resulted in inhibition of TRS induction, indicating that BrUdR had to be incorporated into DNA during at least 48 h. After incorporation, neither the presence of BrUdR nor DNA synthesis was necessary for the production of TRS. These experiments and the finding that in the cell line IHTC-33, which does not produce Epstein-Barr virus associated antigens, TRS were spontaneously present, exclude a correlation between TRS and these antigens. However, the induction of TRS by BrUdR may be related to the activation of another (latent) virus.

Concepts and methods in student mental health

Considering their potential contribution to the community, the growth of clinical services in relation to the specialized mental health problems of students in higher education has been haphazard. Although most universities have developed or are on the way to developing comprehensive health services on the lines recommended in the report of the Royal College of Physicians (1966), services in the non-university sector are often less than adequate. This report accepted as established that about 5 per cent of students have psychological disorders which cause serious distress, and a further 10 to 20 per cent have less severe though handicapping disorders. It was accepted that special provision would need to be made for these mental health problems, as part of the range of preventive and treatment activities relevant to a College community.

The delineation and measurement of study difficulty in university students

Psychiatric disturbances in a student population span a broad spectrum and include overt illness, a heterogeneous group of psychosocial problems with varied and changing symptomatology and normal crises of development. Complaints of work difficulty often form part of the symptomatology of all these groups, and not infrequently may be the presenting symptom. Quantification is difficult because the symptoms vary in degree and form, and change over time. They may be unreported or voiced only to friends or tutors. Their prevalence and significance is therefore hard to assess. In a cohort study spanning a four year period, Lucas (unpublished data) found that of the 15 per cent of the cohort who received brief psychotherapy, more than three-quarters had a work difficulty of some kind. Of the 26 per cent of the cohort who never attended the Student Health Centre nearly half replied ‘yes' to a question asking whether they had experienced recurring work difficulty.

Interaction in university selection, mental health and academic performance

The last decade has seen a shift in the emphasis of research into student problems and student performance. On the psychological side there has been a move away from somewhat static concepts of personality measurement and intellectual assessment, and the concomitant preoccupation with prediction and selection, towards a more interactive approach in which individual aspects are related to academic and social processes (e.g. Sanford, 1962; Lavin, 1965; Wankowski, 1969). On the mental health side there has been a shift from 'syndrome identification’ towards a more dynamic appraisal of personal and social forces and their interaction (Grant, 1969; Ryle, 1969; Lucas and Linken, (1970).