Lymphocyte subset redistribution during acute laboratory stress in young adults: mediating effects of hemoconcentration

Acute psychological stress is known to alter the distribution of circulating lymphocyte subsets and also to cause a reduction of plasma volume. Data were reanalyzed from 4 previously reported studies (E. A. Bachen et al., 1995; T. B. Herbert et al., 1994; A. L. Marsland, S. B. Manuck, T. V. Fazzari, C. J. Stewart, & B. S. Rabin, 1995; A. L. Marsland, S. B. Manuck, P. Wood, et al., 1995) to determine the extent to which changes in the concentration of lymphocyte subsets are attributable to such hemoconcentration. Meta-analytic procedures showed circulating concentrations of T-suppressor/cytotoxic (CD8) and natural killer (NK) cells to increase following acute laboratory challenge, whereas T-helper (CD4) and B- (CD19) cell populations did not change. Adjustments for concomitant hemoconcentration reduced the magnitude of stress-related increases in CD8 and NK cells significantly and revealed a decrease in CD4 and CD19 cell concentrations from baseline to stress measurements. These data provide evidence (a) that increases in circulating numbers of CD8 and NK cells following acute stress are partially attributable to hemoconcentration and (b) that CD4 and CD19 cell concentrations decrease during acute stress when hemoconcentration is taken into account.

Bone marrow-derived dendritic cells, infection with human immunodeficiency virus, and immunopathology

Dendritic cells (DC) exposed to HIV-1 show nonproductive infection that may become productive as they mature. The distribution of DC within genital mucosa and their susceptibility to infection particularly with clade E viruses could be reflected in the ease of heterosexual transmission. Carriage of virus and viral antigen by DC into lymph nodes may allow clustering and activation of T cells and production of protective immune responses. However, secondary infection of activated T cells from infected DC could cause dissemination of virus and loss of infected DC and T cells. In asymptomatic infection, fewer dendritic cells with reduced capacity to stimulate CD4 T cell proliferation are found before evidence of T cell abnormalities, and these early changes in antigen-presenting cells may result in a decline in the production of CD4 memory T cells. However, DC fuel ongoing production of antibody to HIV-1. Signaling by DC to T cells may thus underlie two major features of early HIV infection--loss in CD4+ memory T cells and persistence of antibody production. In AIDS, infected dendritic and epithelial cells within the thymus may affect maturation and contribute to loss of the "naive" T cell population. Further loss of memory T cells may occur through syncytium formation with infected DC. Finally, in AIDS patients, there is a failure in the development and the function of DC from CD34+ stem cells. In conclusion, the infection of dendritic cells, loss in their numbers, and changed signaling to T cells may shape the pattern of immunity during infection with HIV-1. Conversely, treatments that reverse the defect in antigen presentation by DC may improve cell-mediated immunity.

Mechanism for dendritic cell dysfunction in retroviral infection of mice

Dendritic cells (DC) from mice infected with the murine retrovirus Rauscher leukaemia virus (RLV) are poor stimulators of allogeneic and syngeneic T cells and express lower, but still significant, levels of MHC class II. In this paper we further investigated the mechanism of the dysfunction of DC. DC from infected animals did not cause anergy of T cells during coculture for 3 or 6 days. They did not release a substantial amount of soluble factors which could suppress T cell responses. The low T cell responses on stimulation using RLV-infected DC could be overcome by the addition of control DC. Pretreatment of these control DC with monoclonal antibody against MHC class II molecules completely blocked their ability to restore stimulation of T cells in the presence of infected DC. However, antibody against MHC class I or mismatched MHC class II molecules did not prevent restoration of function. The reduced labeling of surface MHC class II molecules previously reported was shown to reflect a loss in total class II molecules within the cells; MHC class I levels were unaltered by exposure to the virus. In DC from RLV-infected mice biosynthesis of MHC class II was decreased by around 50% at the transcriptional level in comparison with beta-actin. Thus, the down-regulation of surface class II molecules observed in DC following RLV infection is a consequence of a specific block in its biosynthesis and the failure of DC to stimulate T cells may be a direct consequence of the reduced class II levels. Since reduced stimulation by DC is also seen in HIV-1 infection in humans we speculate that a similar mechanism might operate in retroviral infection in man.

The effect of AZT on dendritic cell number and provirus load in the peripheral blood of AIDS patients: a preliminary study

In this pilot study, the numbers of dendritic cells (DC) in peripheral blood of AIDS patients and the level of infection with HIV1 were determined before and after AZT treatment. Mononuclear cells were cultured overnight and DC were identified by their lack of labelling with antibodies specific for T, B and natural killer (NK) cells and monocytes and by their high level of staining with antibodies for MHC class II molecules. Although the numbers of DC identified by this method were lower than those identified morphologically in earlier studies (Macatonia et al., 1990), the numbers in three untreated AIDS patients were below the range seen in normals. There was also a marked rise in DC number in patients given AZT therapy. In two patients, there was a significant provirus load in the DCs which was decreased two to three weeks after the commencement of AZT therapy. The studies suggest that DC numbers and their infection levels may be markers of disease in HIV infection.

Health instruction responsibilities for elementary classroom teachers in Pennsylvania

A joint committee comprised of representatives from the American School Health Association and the Association for the Advancement of Health Education delineated five areas of instructional responsibility and 31 competencies needed for elementary health educators. Practicing elementary educators in southeastern Pennsylvania were surveyed as to their usage and perceived importance of these health instruction responsibilities and competencies. Competency usage varied from a high of 98.6% to a low of 33.5%. The second area of instructional responsibility -- Assessing the Health Instruction Needs and Interests of Elementary Students -- had the highest mean usage per competency. Chi-square tests indicated a statistically significant relationship for competency usage and highest academic degree earned for two competencies, while competency usage and total number of years experience as an elementary educator indicated a statistically significant relationship for three competencies. The authors conclude with suggested strategies to improve the health education preparation of elementary educators.

CD4 expression on dendritic cells and their infection by human immunodeficiency virus

Infection of dendritic cells (DC) by human immunodeficiency virus (HIV) has been disputed. Employing a fluorescence-activated cell sorter, DC, identified by the absence of membrane markers for T, B, natural killer (NK) and monocytic cells and by high levels of MHC class II DR antigen, were shown to express low levels of CD4. Immunomagnetic beads were used to separate blood low density cells, which are enriched for DC, into CD4-positive and -negative populations. Examination of these cells by electron microscopy showed an increase in the percentage of cells with DC morphology in the CD4-positive fraction and a reduction in the CD4-negative fraction. Electron microscopy of semi-purified DC preparations infected in vitro for 5 days with HIV-1 revealed morphologically distinct veiled DC with mature virions on the cell surface and virus budding through the cell membrane. Further evidence for the growth of HIV in DC was provided by experiments in which DC were extensively depleted of contaminating lymphocytes and monocytes prior to infection. Estimation of provirus load by a nested PCR indicated that after 5 days an infection level of one provirus copy per five cells could be achieved. After 7 days the provirus copy number could exceed the cellular genome copy number, suggesting that some cells had more than one provirus. Infectious virus could not be demonstrated in these cultures after 24 h but was detected after 5 or 7 days. Infection of DC in the presence of antibodies against CD4 was inhibited and suggests infection occurs via a CD4-dependent pathway. These results confirm that DC are susceptible to HIV infection in vitro. The immunological consequences of DC infection in vivo may be significant in the pathogenesis of AIDS.

Intraoperative somatosensory evoked potential monitoring during acute pelvic fracture surgery

Independent clinical neurological evaluation and intraoperative somatosensory evoked potential (SSEP) monitoring was performed on 30 vertically unstable hemipelvis fractures in 28 patients undergoing acute open reduction and internal fixation. Preoperative ipsilateral neurologic injury of the sciatic/lumbosacral plexus was noted in 15 of 30 fractures (50%). Significant unilateral SSEP changes occurred during manipulative reduction of two displaced sacroiliac joints and one sacral fracture. Because of the expeditious response of the surgical team, with release of traction/retraction, SSEP returned to baseline and no patient sustained an iatrogenic nerve injury or worsening of their preoperatie neurologic status. The incidence of postinjury lumbosacral plexopathy in unstable pelvic fractures is high (50%) when careful preoperative evaluation including SSEP is performed. The use of intraoperative SSEP monitoring is feasible in acute posterior pelvic fracture surgery and can help identify potential intraoperative iatrogenic lumbosacral neurological compromise.

Increased erythrocyte sedimentation rate and a splenic mass

This discussion was selected from the weekly Grand Rounds in the Department of Medicine, University of Washington School of Medicine, Seattle. Taken from a transcription, it has been edited by Jonathan G. Drachman, MD, Chief Medical Resident; Henry Rosen, MD, Professor and Associate Chair; and Paul G. Ramsey, MD, Professor and Chair of the Department of Medicine.

Murine retrovirus induces defects in the function of dendritic cells at early stages of infection

The infection and function of lymph node dendritic cells (DC) were analyzed at different time points of Rauscher leukemia virus infection in mice (3, 7, 14, and 21 days). Infection of DC was apparent after 3 days and significant infection (1-10% of the DC population) was documented after 7 days. DC from infected mice as early as 3 days postinfection had a reduced ability to stimulate allogeneic normal T cells in the mixed lymphocyte reaction. T cells did become infected during the coculture but block of cross-infection of T cells by zidovudine did not abolish the inhibitory effect. Other DC-dependent responses were also reduced on infection including DC-stimulated responses to influenza virus. ConA and PMA induced an increase in [Ca2+]i level in DC from control mice. A low baseline level of [Ca2+]i in DC from infected mice and reduced calcium mobilization upon ConA stimulation was found at all periods of infection. Ultraviolet-inactivated Rauscher leukemia virus failed to provoke significant changes in DC function in vivo. Six or 7 days after RLV infection DC expressed lower levels of Iad but not H2Dd molecules in parallel with lower expression of some adhesion molecules (CD18, CD54, CD44). No differences in expression of B7 surface antigen between control and infected mice were obtained. We did not find any evidence for the induction of apoptosis of naive syngeneic or allogeneic T cells by infected dendritic cells. The changes in DC function may have implications for the pathogenesis of retroviral infections including HIV infection.

Analysis of a naturally occurring K99+ enterotoxigenic Escherichia coli strain that fails to produce K99

A spontaneously occurring field isolate of enterotoxigenic Escherichia coli that was genotypically K99+ but phenotypically K99- was analyzed for the reason that it did not express K99. The defect, which was cis active, was located within an area 5' to the first gene required for K99 biogenesis and was the result of the deletion of a single base pair.

Dynamic external fixation of unstable fractures of the distal part of the radius. A prospective, randomized comparison with static external fixation

A prospective, randomized study was done to compare the results of dynamic external fixation (the Clyburn device) with those of static external fixation (the AO/ASIF device) in the treatment of fifty unstable fractures of the distal part of the radius. Mobilization of the wrist from neutral to 30 degrees of flexion was begun in the dynamic-fixator group at approximately two weeks, and full motion, allowing 30 degrees of extension, was started at approximately four weeks. The external fixation frames in both groups were kept in place for approximately ten weeks. Mobilization of the wrist in the dynamic-fixator group provided little gain in the mean motion of the wrist at the time of the removal of the fixator or at the one, six, or twelve-month evaluation. The static-fixator group had greater flexion of the wrist and radial deviation at the early and late follow-up examinations, while the dynamic-fixator group demonstrated only greater ulnar deviation one month after the fixator had been removed. Motion of the wrist in the dynamic-fixator group resulted in a statistically significant loss of radial length compared with that in the static-fixator group (four millimeters compared with one millimeter, p < 0.001). Complications were more frequent in the dynamic-fixator group. As evaluated with a modification of the scoring system of Gartland and Werley, 92 percent of the results at one year were excellent or good in the static-fixator group and 76 percent, in the dynamic-fixator group. The results of this study cannot support the concept of early mobilization with a dynamic external fixator for the treatment of unstable fractures of the distal part of the radius.

Blunted natriuretic response to a high-sodium meal in obese dogs. Role of renal nerves

Although the relation between body weight and arterial pressure is well established, the mechanisms involved in the pathogenesis of obesity-related hypertension are unclear. However, recent studies suggest that abnormalities in renal function may be involved. The purpose of this study was to test the hypothesis that obese animals have a reduced ability to excrete a sodium load as a result of abnormal renal nerve function. To quantify the role of renal nerves, we examined changes in renal hemodynamics and sodium excretion in response to a high-sodium meal (200 mmol Na) in separate innervated and denervated kidneys simultaneously within the same conscious dog. Two surgically designed hemibladders with indwelling catheters were used to collect urine from innervated and denervated kidneys of the same dog. Body weight averaged 19.9 +/- 1.0 kg in the control lean dogs and 25.1 +/- 1.1 kg in the obese dogs. Arterial pressure averaged 101 +/- 4 mm Hg in the obese dogs and 90 +/- 4 mm Hg in the lean dogs. In response to the high-sodium meal in lean dogs, urinary sodium excretion increased from 20.8 +/- 4.2 to 189.7 +/- 21.2 mumol/min in the innervated kidneys and from 25.3 +/- 5.9 to 194.8 +/- 26.9 mumol/min in the denervated kidneys. In contrast, urinary sodium excretion in obese dogs increased from 9.6 +/- 1.4 to 129.9 +/- 34.3 mumol/min in the innervated kidneys and from 18.4 +/- 3.7 to 125.2 +/- 30.5 mumol/min in the denervated kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Clonal integration in Spartina patens across a nitrogen and salinity gradient

We investigated physiological integration among ramets of Spartina patens when clones spanned a salinity gradient. Clones of S. patens were grown in paired pots with the ramets of the parent pot connected to the ramets of the daughter pot via a common rhizome. Half of these clones had the rhizome connection between parent and daughter pots severed immediately prior to treatment application. The parent pots were kept at low salinity (34.2 mM NaCl) and given two levels of labeled 15NH4Cl (0.036 or 0.714 mM NH4Cl). Daughter ramet pots were kept at the low N level (unlabeled 0.036 mM NH4Cl) and exposed to an increase in salinity to 513 mM NaCl. After 7 days, all daughter ramets had significantly elevated leaf Na levels. Daughter ramets connected to parents were able to maintain significantly greater leaf elongation rates than severed daughter ramets. Labeled 15N was translocated from parents to connected daughter ramets and high-N parents translocated more N to the belowground tissue of daughter ramets than low-N parents. Leaf proline, a nitrogen-containing osmoticum that accumulates only after a threshold of salinity stress is exceeded, was significantly increased only in severed daughter ramets, indicating that salinity stress was reduced in connected daughter ramets, possibly via parental water translocation. Key words: clone, physiological integration, proline, ramet, salt marsh, salt stress.

Retrovirus-induced immunosuppression via blocking of dendritic cell migration and down-regulation of adhesion molecules

Dendritic cells (DC) within tissues may acquire and process antigens, carry them into lymph nodes and cluster and activate T cells. The ability of DC to acquire antigen and to migrate to lymph nodes was estimated during murine retroviral infection caused by Rauscher leukaemia virus (RLV). A novel mechanism of inducing immunodeficiency has now been identified. In mice infected with RLV, DC failed to migrate into lymph nodes following exposure of the skin to the contact sensitizer, fluorescein isothiocyanate. RLV infection of a proportion of DC both in skin and lymph nodes, shown by semi-quantitative polymerase chain reaction (PCR) and down-regulation of expression of adhesion molecules (CD54 and CD44) on the surface of Langerhans' cells, may contribute to the described phenomenon. A failure of DC migration could be an important immunosuppressive mechanism of RLV infection in mice and we speculate on a similar role for DC in human immunodeficiency virus-1 (HIV-1) infection in humans.

Detection of HIV DNA in peripheral blood dendritic cells of HIV-infected individuals

Previous studies from this laboratory indicated infection of dendritic cells (DC) from peripheral blood of individuals infected with HIV1. Here, further evidence for the infection of peripheral blood DC with HIV1 is presented. Low-density cells (LDC) were prepared from blood mononuclear cells of HIV-infected individuals at different clinical stages of disease. These cells are enriched (10-40%) for MHC class-II-bearing DC, while most of the remaining cells are monocytes, and 2-10% are lymphocytes. A quantitative polymerase chain technique (PCR) was used to estimate the HIV provirus load in LDC and lymphocytes of patients in different disease categories. HIV provirus was detected in every LDC preparation, and for many individuals, particularly CDC stage IV patients, the load was higher in the LDC than in the lymphocyte fraction. These findings suggested that patient DC are infected with HIV. In order to provide confirmatory evidence for this conclusion, PCR was performed on DC that were highly purified from LDC by panning to remove contaminating T, B, natural killer and monocytic cells. High levels of HIV provirus were found in these purified DC. These findings suggest that DC provide a reservoir of HIV and that the consequences of such infection may be relevant to the development of disease.

Reliability of measurements of static weight distribution of manual wheelchairs

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the reliability of measurements of weight distribution among the wheels of wheelchairs using a commercial balance testing system. Reliable data may be useful in the wheelchair evaluation and adjustment process.

SUBJECTS

Three male full-time manual wheelchair users aged 30, 26, and 27 years with cervical spinal cord injuries 7.5, 6.5, and 10 years in duration participated.

METHODS

Calibration weights, unoccupied wheelchairs, and occupied wheelchairs were repeatedly placed on the force transducers of the balance testing system to obtain measurements of weight distribution.

RESULTS

The intraclass correlation coefficients of the measurements were .99 for calibration weights, .96 for unoccupied wheelchairs and .98 for wheelchairs occupied by the subjects.

CONCLUSION AND DISCUSSION

The described use of this instrumentation appears to generate reliable measurements of static weight distribution. With further testing, this system may provide useful information related to manual wheelchair prescription and adjustment.

Evoked potential monitoring during posterior fossa aneurysm surgery: a comparison of two modalities

The purpose of this study was to compare and assess the ability of two different evoked potential (EP) modalities, median nerve somatosensory evoked potentials (SSEP) and brainstem auditory evoked potentials (BAEP) in monitoring for cerebral ischaemia and in predicting neurological outcome during posterior fossa aneurysm surgery. During 70 procedures, patients were monitored with both SSEP and BAEP. Temporary occlusion of an artery was used in 52 patients and permanent occlusion in 21 patients. A change was defined as a greater than 50% decrease in amplitude and/or an increase in latency greater than 1 msec of the N20 (cortical waveform) for SSEP monitoring and of the fifth peak for BAEP monitoring. Neurological assessment of the patient was performed immediately on emergence, after 24 hr and at the time of discharge. In total, 14 patients had an SSEP change which predicted a neurological deficit in eight patients (57%). Ten patients had a change in BAEP; six had a neurological deficit (60%). Five patients had a change in both, two had a deficit (40%). The incidence of false negative results (a neurological deficit but no EP change) for both modalities was 20% (SSEP 47%, BAEP 60%). The incidence of false positive results (an EP change but no deficit) was 13% overall (SSEP 11%, BAEP 7%). All patients who had a permanent EP change developed a neurological deficit. We did not find a difference in the ability of SSEP compared with BAEP in predicting neurological deficits but, using both modalities, the incidence of false negative results was decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Is use of hospital services a proxy for morbidity? A small area comparison of the prevalence of arthritis, depression, dyspepsia, obesity, and respiratory disease with inpatient admission rates for these disorders in England

OBJECTIVES

To examine the relationship between specific types of morbidity, measured by validated survey questions, and hospital service use and mortality to see if the latter two could act as a proxy in health needs assessment, health service planning, and resource allocation in a typical health district.

DESIGN

A postal questionnaire was used to provide information about depression, digestive disorders, musculo-skeletal disorders, obesity, respiratory disease, and hip and knee pain. The questions were from survey instruments that have been widely used to derive information about these conditions. The relationships between the prevalence of these specific types of morbidity and appropriate admission and mortality rates were explored using linear regression and Pearson correlation analysis.

SETTING

The population of Rotherham health district, England.

SUBJECTS

A simple random sample of the residents of each of the 22 electoral wards in Rotherham health district.

RESULTS

Responses were obtained from 78% of the 5000 sampled (82% after excluding people who had moved house or died). Significant, positive correlations were found between the prevalence of respiratory disease and the hospital admission and mortality rates for respiratory problems (r = 0.68, p < 0.01 and r = 0.54, p < 0.01) and the prevalence of depression and the admission rate for depression (r = 0.52, p < 0.05). No such relations were found for digestive disease, musculo-skeletal disease, and obesity. For the conditions examined here, hospital service use was a more useful measure than mortality.

CONCLUSIONS

Only two diseases (respiratory disease and depression) out of the seven diseases or procedures investigated showed a positive correlation between hospital admission and disease prevalence. But even for these two, the correlations explained less than 50% of the variance. Caution must be exercised when hospital service use is being considered as a proxy for morbidity.

Dendritic cells infected in vitro with human T cell leukaemia/lymphoma virus type-1 (HTLV-1); enhanced lymphocytic proliferation and tropical spastic paraparesis

Evidence supporting a role of the dendritic cell (DC) in stimulating autologous T cell activity in tropical spastic paraparesis (TSP) was sought by studies of cells taken from healthy volunteers and exposed to HTLV-1 in vitro. DC were co-cultured with an HTLV-1-producing cell line (MT-2) at 1:1 or 10:1 ratios. These DC stimulated high levels of proliferation in autologous T cells. This was similar to that seen in an autologous mixed leucocyte reaction (AMLR) using cells from TSP patients. The requirement for both DC and virus was confirmed, since neither DC co-cultured with uninfected MT-2 cells nor addition of infected MT-2 cells directly to T cells caused significant stimulation. DC exposed to the highest dose of HTLV-1 (1:1) for 24 h before addition of T cells caused strong stimulation that increased after 8 h but almost disappeared by 72 h. In situ hybridization showed that approximately 25% of DC became infected in cultured cells after preincubation for 24 h, and over 50% were infected with a 72-h preincubation. We suggest that infection of DC by HTLV-1 may be an initial step in altering the immune system in seronegative patients, and that persistent T cell stimulation in those with genetic susceptibility may underlie the production of neurological disease.

Are deprivation indicators a proxy for morbidity? A comparison of the prevalence of arthritis, depression, dyspepsia, obesity and respiratory symptoms with unemployment rates and Jarman scores

The aim of the study was to examine the relationship between specific areas of morbidity measured using validated survey questions and deprivation indicators to see if the latter could act as a proxy in health needs assessment, health service planning and resource allocation in a typical health authority. A postal questionnaire was used to provide information about arthritis, depression, dyspepsia, obesity and respiratory symptoms in a simple random sample from the study population. The questions were from survey instruments that have been widely used to derive information about these conditions. The relationships between the prevalence of these specific areas of morbidity and both unemployment and the Jarman Underprivileged Areas Score were explored. Spearman's rank correlation coefficients were calculated and compared for each combination of measures. The study population was a random sample of the residents of each of the 22 electoral wards in Rotherham Health Authority. Responses were obtained from 82 per cent of the 5000 sampled. Although all morbidity measures showed positive correlations with both Jarman score and unemployment, some, notably those relating to respiratory disease and depression, were much more strongly correlated than others, such as obesity. There was no difference between unemployment and Jarman score in respect of the magnitude of the correlation coefficients. In conclusion, for some, but not all, conditions socio-economic measures are a good proxy for morbidity. Unemployment is just as useful a proxy as the Jarman score.

Sometimes Jello helps: perceptions of headache etiology, triggers and treatment in literature

Throughout history writers have attempted to describe the symptoms and evoke the misery of "a dismal headache." Writers from Plato to Stephen King have used the phenomenology of headache to illustrate their work. Lewis Carroll, for example, vividly describes the central scotoma, tunnel vision, phono-phobia, vertigo, distortions in body image, dementia and visual hallucinations that often accompany migraine. Although many authors have discussed the topic seriously, others have addressed the issue in a dismissive and even contemptuous manner, relegating this very real disorder to the status of a medical stepchild. We will examine headache etiology, triggers and treatment and explore the attitudes toward headache and headache sufferers found in literature. We have recently seen a growing understanding of the physiological basis of headaches. However, this knowledge has not yet reached the level of literature or popular culture. In an age when it seems every Sunday night brings a new "disease of the week" movie, and every human ill is subjected to often intense and numbing scrutiny by the media, the anguish of a chronic migraine sufferer will probably remain unexplored--unless she kills her husband and children during an attack.

Dendritic cells in HIV-1 and HTLV-1 infection

Individuals with HIV-1 infection show two major immunological effects--the early persistent stimulation of immune responses (e.g. of CD8 cells and antibody production) and later catastrophic immunodeficiency. Peripheral blood dendritic cells (DC) become infected with HIV-1 and infected cells can stimulate responses to virus. By contrast infected DC show a reduced capacity to stimulate either primary or secondary responses to other antigens. We have proposed that the block, particularly in primary responses, may be instrumental in the development of immunodeficiency. In HTLV-1 infected patients with tropical spastic paraparesis (TSP) a major feature of disease is 'spontaneous' T cell proliferation thought to underlie development of inflammatory neurological disease. We have now shown that some DC in addition to T cells are infected in TSP and that DC stimulate the persistent T cell activity. Here we demonstrate this using cells from an informative family where the daughter was normal, the father an HTLV-1 seronegative carrier and the mother had TSP. DC from all individuals stimulated normal allogeneic T cells in a mixed leukocyte reaction (MLR) and T cells responded well to normal allogeneic DC. T cells from the daughter showed little stimulation with autologous DC, those from the father showed significant but low stimulation, and T cells from the TSP patient gave a response to autologous DC which exceeded that to allogeneic DC. Taken together, the studies of DC and both HIV-1 and HTLV-1 indicate that infection of DC may play a central role in development of T cell abnormalities in human retrovirus-induced diseases.

Infection of dendritic cells with HIV1: virus load regulates stimulation and suppression of T-cell activity

Patients with HIV infection show two major types of immunological effects. The first is hyperactivity of both T and B lymphocytes which may be in response to HIV antigens themselves, and the second is a loss in T-cell activity in response to other antigens. Dendritic cells (DC) show a higher rate of infection with HIV than other peripheral blood cells in vitro and in vivo. The effects of HIV infection of DC in vitro on their stimulating capacity for T cells were, therefore, examined. We compared the development of the capacity to stimulate primary proliferative responses to virus in autologous lymphocytes with their potency in stimulating allogeneic cells in the mixed leukocyte reaction (MLR). Small numbers of uninfected DC caused little or no stimulation of autologous lymphocytes, but stimulated high MLR. The level of HIV infection in in vitro infected DC preparations was dependent on the time of infection and the titre of the input virus. DC exposed to low doses of HIV (e.g., 10(3) TCID/10(6) cells) for up to 4 days or to a higher dose (e.g. 10(5) TCID/10(6) cells) for 1 day caused significant primary proliferation in autologous T cells and, under these conditions, capacity to stimulate allogeneic MLR remained intact. However, DC exposed to increasing doses of HIV or infected for a longer period showed reduced capacity to stimulate allogeneic lymphocytes and then a loss of stimulation of autologous cells. This provides evidence suggesting that both stimulatory and inhibitory effects of HIV infection can be produced through infection of DC.

Medium technology in health care

The health care industry relies on technological innovation to provide solutions to the ever increasing range of medical problems in the modern world. No industry can survive without financial investment, and some areas of the health care industry have encountered difficulties when trying to attract finance. In this article, the author outlines specific areas that are likely to attract investment funding and the elements that make up an attractive proposition for potential investors.

Antigen-presentation by macrophages but not by dendritic cells in human immunodeficiency virus (HIV) infection

Dendritic cells (DC) have a potent antigen-presenting capacity for recruiting resting T cells into immune responses. They also promote expansion of already activated memory T cells. By contrast, macrophages (M phi) are only effective in stimulating memory responses. Infection and depletion of DC occur in human immunodeficiency virus (HIV)-infected individuals and recruitment of T cells into primary responses is blocked. Here comparisons between DC and M phi in stimulating secondary T-cell responses in HIV infection were made. Adherent M phi, and DC isolated by a new method, were separated from peripheral blood of patients in different stages of HIV infection and from uninfected controls and added to allogeneic lymphocytes in mixed leucocyte reactions (MLR). Some were pulsed with influenza virus or tetanus toxoid and used to stimulate autologous T cells. Responses were measured from uptake of [3H]thymidine in 20 microliters hanging drop cultures. DC, but not M phi, from normal individuals stimulated MLR but both populations stimulated secondary responses to recall antigens. DC from all HIV seropositive individuals caused little or no stimulation of any lymphocyte responses. However, M phi from HIV seropositive asymptomatic individuals and those with persistent generalized lymphadenopathy stimulated responses to recall antigens. There was no stimulation using cells from acquired immune deficiency syndrome (AIDS) patients. Blocked DC but not M phi function may underlie progressive immunological non-responsiveness in HIV infection. Without recruitment of resting T cells, loss of memory T cells may be cumulative; failure of secondary activation (e.g. by M phi) would lead to lost T-cell activity. Identification and circumvention of the defect in DC could offer new therapeutic approaches.

Primary proliferative and cytotoxic T-cell responses to HIV induced in vitro by human dendritic cells

In earlier studies, primary proliferative and cytotoxic T-cell (CTL) responses to influenza virus were produced in vitro by using mouse dendritic cells (DC) pulsed with virus or viral peptide as the stimulus for syngeneic T cells in 20-microliters hanging-drop cultures. We have now adapted this system for producing primary responses with cells from non-immune donors to produce primary proliferative and CTL responses to human immunodeficiency virus I (HIV) and to HIV peptides in vitro using cells from normal human peripheral blood. All donors in this study were laboratory personnel with no history of HIV infection. DC enriched from peripheral blood were exposed to HIV in vitro and small numbers were added to T lymphocytes in 20-microliters hanging drops. Proliferative responses to virus-infected DC were obtained after 3 days in culture. After 6 days, CTL were obtained that killed virus-infected autologous--but not allogeneic--phytohaemagglutinin (PHA)-stimulated blast cells. Proliferative and CTL responses were obtained using cells from 14 random donors expressing a spectrum of major histocompatibility complex (MHC) types but the CTL, once produced, showed killing restricted by the MHC class I type. Treatment of cultures with monoclonal antibody (mAb) to CD4-positive cells at the beginning of culture blocked the development of both proliferative and CTL responses, but treatment after 5 days had no effect on the CTL activity. Treatment with MCA to CD8-positive cells at the beginning of culture did not block proliferation significantly, but treatment either before or after the 5-day culture period blocked CTL responses. Collaboration between proliferating CD4-positive cells and CD8-positive cells may thus be required to produce CTL of the CD8 phenotype. DC exposed to HIV also produced CTL that killed autologous blast cells pulsed with gp120 envelope glycoprotein. However, DC infected with whole virus did not produce CTL that lysed target cells pulsed with a synthetic peptide, which included a known T-cell epitope of gp120 (representing amino acids 111-126). DC pulsed with gp120 were a poor stimulus for the development of CTL. In contrast, DC pulsed with the peptide (111-126) stimulated both proliferative and CTL responses. The latter killed not only target cells pulsed with the peptide itself or with gp120 but also killed virus-infected autologous blast cells. CTL were again obtained reproducibly with this peptide using donors expressing a spectrum of MHC types.(ABSTRACT TRUNCATED AT 400 WORDS)

Stimulatory and suppressive effects of infection of dendritic cells with HIV-1

Two effects of HIV infection on human dendritic cells (DC) in vitro have been examined. The first was the stimulation of primary responses to HIV antigens in autologous lymphocytes from normal donors. When DC were exposed to HIV (10(4) TCID/10(5) cells) for up to 24 h before addition to autologous lymphocytes, a marked primary proliferative response to the virus was observed. No proliferative response was seen when the period of pre-exposure of DC to virus was extended. Cytotoxic T cells specific for HIV-infected target cells developed in stimulated cultures. The second effect of HIV infection of DC was to block responses to other antigens, such as alloantigens and the recall antigens tetanus toxoid and influenza virus. This inhibitory effect was only evident when the DC were exposed to HIV for longer than 24 h before being added to cultures. These in vitro studies suggest that infection of DC can produce both stimulatory and inhibitory responses in lymphocytes. Such effects operating through DC might underlie in vivo activity of HIV both in stimulating the proliferation of lymphocytes (e.g., in persistent generalised lymphadenopathy) and in the development of immunosuppression.

A tape-recorded test of hypnotic susceptibility for screening headache patients: a feasibility study of the Harvard Group Scale of Hypnotic Susceptibility, Form A

A study to examine the feasibility of using the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS) as a screening instrument was undertaken at an inpatient headache treatment program. Nine patients diagnosed with chronic daily headache and drug rebound were administered the HGSHS. Analysis of the results showed no significant difference in hypnotic susceptibility when headache patients were compared to a control group. After taking the HGSHS, three of the five subjects who had headache at the time of testing reported a 25% reduction in pain, one was unchanged, and one reported a 13% increase in pain. The results obtained did not suggest a correlation between level of hypnotic susceptibility and reduction of headache.

Morphology and phenotype of dendritic cells from peripheral blood and their productive and non-productive infection with human immunodeficiency virus type 1

Immununoelectron microscopy of human peripheral blood mononuclear cells enriched for the presence of antigen-presenting dendritic cells (DC) has revealed two morphologically distinct cell types both expressing DR and DQ major histocompatibility complex (MHC) class II antigens but lacking T, B, natural killer (NK) and monocyte/macrophage markers. The first (type 1) has an irregular surface with numerous projections and shows cytoplasmic vacuoles. The second (type 2) has a paler nucleus showing only a thin rim of dense heterochromatin, large expanses of cytoplasm devoid of organelles, fewer vacuoles and a smooth cell boundary with few processes. In addition a few cells with a morphology similar to veiled cells of the afferent lymphatics (type 3 DC) were observed. Cells with a morphology intermediate between these three types were observed, suggesting that they may represent stages of the veiled cell differentiation pathway. Type 2 and 3 DC were shown by electron microscopy to be susceptible to productive infection with human immunodeficiency virus (HIV), whilst type 1 DC did not support virus growth. Examination of infected DC preparations by in situ hybridization revealed a higher number of DC positive for viral DNA and RNA than for RNA alone. Thus, in addition to productively infected DC, there may be some that are latently infected, contain defective virus genome or replicate virus at a very low level.

Dendritic cell infection, depletion and dysfunction in HIV-infected individuals

Immune responses in resting T cells are initiated by the presentation of antigen by bone marrow-derived dendritic cells (DC). Normal DC are susceptible to infection with human immunodeficiency virus (HIV) in vitro (Patterson & Knight, 1987) and this blocks their capacity to stimulate T-cell responses to other antigens (Macatonia, Patterson & Knight, 1989a). To study the relationship between HIV and DC in patients and its relevance to the pathogenesis of disease, DC have been isolated from the blood of individuals in the different clinical categories, counted, examined for the presence of virus genome and their antigen-presenting capacity measured. Infection, depletion and impaired function of DC occur in early HIV infection. HIV seropositive patients who were asymptomatic and those with symptoms of disease had significantly reduced numbers of DC, but patients with persistent generalized lymphadenopathy had normal numbers. Between 3% and 21% of DC, identified as large low-density cells not bearing monocyte, lymphocyte or natural killer cell markers, were infected with HIV, as indicated by in situ hybridization. Less than 0.12% of the lymphocytes or monocytes were infected. The DC from infected individuals were poor at enhancing responses to the mitogen concanavalin A (Con A). They also caused low levels of stimulation in allogeneic lymphocytes in mixed leucocyte cultures. By contrast, T cells from asymptomatic patients gave normal T-cell responses to uninfected allogeneic DC, although those from acquired immunodeficiency syndrome (AIDS) patients did show reduced responsiveness. Defects in DC thus precede both the appearance of symptoms and changes in T cells and may be instrumental in the development of AIDS. Furthermore, since DC numbers and function differ at different stages of disease, monitoring these may contribute to clinical assessment and lead to new therapeutic approaches.

HIV I infection of dendritic cells

Dendritic cells (DC) from human peripheral blood are susceptible to productive and probably to latent infection with HIV-I. Infection of DC also occurs in vivo since in HIV-seropositive individuals Langerhans' cells of the skin and DC from peripheral blood, (in preparation) are infected. In peripheral blood 3-25% of DC, identified as large, low-density cells lacking monocyte markers, are infected as judged by in situ hybridization with an HIV probe. This contrasts with the lower proportion (< 0.2%) of other cells infected. DC exposed to HIV in vitro or in vivo fail to present other antigens or mitogens to stimulate T cells. This functional defect in infected DC is not blocked by the presence of soluble CD4 antigen and occurs in the absence of T cell infection suggesting a block at the level of the antigen-presenting cell itself. Infection, depletion and dysfunction of DC in HIV seropositive patients is already present in asymptomatic individuals and this precedes the appearance of T cell defects. We speculate that loss of functional DC may be a fundamental defect leading to a block in recruitment of resting T cells into immune responses. In contrast to the HIV-induced impairment of antigen presentation by DC, these cells were potent stimulators of responses to the HIV antigens themselves. Normal DC infected with HIV in vitro stimulated primary proliferative and cytotoxic T cell responses (in preparation). These were produced in cells from individuals expressing a range of different MHC types but the cytotoxic cells, once produced, killed autologous but not allogeneic, infected T cell blasts. Primary response to viral peptides can also be produced suggesting that this system may be useful for identifying immunogenic epitopes of HIV using cells from sero-negative, non-immunocompromised individuals.

Suppression of immune responses by dendritic cells infected with HIV

Evidence of human immunodeficiency virus (HIV) replication both in the skin Langerhans' cells of AIDS patients (Tschachler et al., 1987) and in normal, peripheral blood dendritic cells (DC) (Patterson & Knight, 1987; Knight & Patterson, 1989) suggests that infection of these antigen-presenting cells may contribute to the immunosuppression seen in AIDS. Support for this hypothesis is now provided by experiments in which the capacity of DC infected in vitro to present mitogen to normal syngeneic lymphocytes was measured. Infecting DC with HIV before culturing with lymphocytes inhibited mitogen-stimulated cell proliferation. Viral DNA was detected in DC in these cultures by in situ hybridization but, in addition, HIV was also present in a small proportion of lymphocytes. However, introducing an inhibitor of virus replication, 2',3' dideoxyadenosine, after infection of the DC but before culturing with lymphocytes, blocked growth of HIV in lymphocytes. In these latter experiments mitogen proliferation responses were still suppressed. Infection of DC could, therefore, cause immunosuppression in AIDS, both by direct effect on antigen-presentation and by the transfer of HIV to T cells.

DNA probes bind non-specifically to eosinophils during in situ hybridization: carbol chromotrope blocks binding to eosinophils but does not inhibit hybridization to specific nucleotide sequences

Eosinophils were found to bind radiolabelled DNA probes non-specifically during in situ hybridization. Pretreatment of cells with carbol chromotrope blocked non-specific binding without interfering with the recognition of specific nucleotide sequences.

Role of retroviruses in acquired hypogammaglobulinaemia

Mononuclear cells were obtained from 42 patients with 'common variable' hypogammaglobulinaemia (CVH) and co-cultured with various cell lines in an attempt to isolate retroviruses. Cultures from only two patients showed evidence of a viral infection, although the virus could not be isolated and characterized in either. Despite the previous isolation of HIV's from two other CVH patients, this data suggests that similar viruses are not etiologically involved in the majority of patients.

Infection of B lymphocytes by the human immunodeficiency virus and their susceptibility to cytotoxic cells

The T4 molecule (CD4) is an important component of the human immunodeficiency virus (HIV) receptor. As yet, no other component has been demonstrated. We report here that two cell lines, a B lymphoblastoid cell line (Gupta) and a glial cell line (HEB) derived from human embryonal brain tissue, are productively infectable with two distinct isolates of HIV as judged by electron microscopy and immunological and virological studies. These two cell lines do not display detectable surface CD4 glycoprotein. However, using S1 nuclease analysis, we have found that both cell lines do express low levels of CD4 mRNA. Neither of them produced syncytia formation upon HIV infection, a recognized feature of HIV-infected cells strongly expressing the CD4 glycoprotein. It is conceivable that the CD4 mRNA is translated, resulting in meager surface expression of CD4 molecules undetectable by conventional techniques. Therefore, infection with HIV may be one of the most sensitive methods of demonstrating low levels of CD4 expression by human cells. Furthermore, HIV-infected Gupta cells have here been shown to be more susceptible to the lytic activity of natural killer (NK) cells than their uninfected counterparts. These phenomena may be important for pathogenesis of HIV-associated disorders.

The intracellular distribution of influenza virus matrix protein and nucleoprotein in infected cells and their relationship to haemagglutinin in the plasma membrane

Pre- and post-embedding immune electron microscopy techniques employing ferritin and large and small gold markers to detect cell surface and intracellular antigens respectively, have been combined in a study of influenza virus-infected cells. This has permitted, for the first time, the simultaneous detection of intracellular virus matrix protein (M), nucleoprotein (NP) and membrane haemagglutinin (HA). The technique facilitated an investigation of the possible physical interrelationship between these three proteins both in the infected cell, and on the infected cell membrane. Electron-dense bodies uniformly labelled by antibody to M protein were observed in the nucleus and cytoplasm. Similarly, NP was detected in both the nucleus and cytoplasm. Approximately 50% of the nuclear NP was located in close proximity to the M protein-containing dense bodies but mainly on the perimeter of the structures. A similar relationship of NP to the M-containing dense bodies was observed in the cytoplasm. M protein and NP were readily detected in sections of budding virions. Labelling of these proteins was also observed on the cytoplasmic face of the plasma membrane but the density of labelling only occasionally approached that of newly formed virions. These findings suggest that budding occurs very quickly after the internal proteins arrive at the plasma membrane. Double labelling experiments on the cell surface indicate that NP and HA behave as independent molecules and do not form tight complexes with each other.

Morphologic analysis of the interactions between lymphocytic choriomeningitis virus-specific cloned cytotoxic T cells and virus infected targets

The interactions between lymphocytic choriomeningitis virus-specific cloned cytotoxic T lymphocytes (CTL) and virus infected targets have been examined by electron microscopy. CTLs, which were readily differentiated from target cells by the presence of cytoplasmic granular inclusions, made intimate contact with infected cells. Some CTLs contacted infected cells via numerous interdigitating processes; others were observed thrusting finger-like protrusions deep into the target cell; some were seen with their plasma membranes lying closely opposed to that of the infected cell. The majority (55%) of bound CTLs had their Golgi apparatus oriented towards the target cell and 42% of bound CTL had granular inclusions in close proximity to the contact zone. Evidence is presented which suggests that the contents of the granular inclusions are released by CTLs in contact with infected cells. Granules appeared to be released close to the target cell rather than from random sites on the CTL surface. Examination of supernatants from effector-target cell incubation mixtures by negative staining revealed membranes bearing lesions with an internal diameter of approximately 15 nm.