Cellular and humoral immunogenicity of the COVID-19 vaccine and COVID-19 disease severity in individuals with immunodeficiency

Background

A well-coordinated adaptive immune response is crucial for limiting COVID-19 disease. Some individuals with immunodeficiency are at a high risk of developing severe COVID-19. Therefore, the development of standardized methods for measuring different arms of the vaccine response in the setting of immunodeficiency is of particular interest. In this study, we compared the vaccine response of individuals living with immunodeficiency with healthy controls in terms of interferon gamma (IFN-γ) production and spike protein-specific antibody level post primary COVID-19 vaccination and booster vaccines. Additionally, the disease severity of those individuals who contracted COVID-19 was assessed.

Methods

Whole blood was stimulated overnight from 71 participants and 99 healthy controls. Commercially available PepTivator^® peptide pool and trimeric spike protein stimulation were used. ELISA was used to analyze IFN-γ levels. The total SARS-CoV-2 spike protein antibody titre was measured using a Roche Elecsys^® S total antibody assay. Patient characteristics, COVID-19 infection status and IDDA 2.1 'Kaleidoscope' scores were recorded. Vaccine responses were scored from zero to three.

Results

99% of healthy controls, 89% of individuals with IEI and 76% with secondary immunodeficiency (SID) had an IFN-γ level above the validated reference range after peptide mix stimulation following primary vaccination. There was an increase in IFN-γ levels in patients with inborn errors of immunity (IEI) following the booster vaccine (p = 0.0156). 100% of healthy controls, 70% of individuals living with IEI and 64% of individuals living with SID had detectable spike protein-specific antibody levels following the primary vaccination. 55% of immunodeficiency patients who had mild COVID-19 and 10% with moderate/severe COVID-19 had detectable antibody and IFN-γ levels post vaccine. The mean pre-infection IDDA 2.1 scores were higher in individuals who developed moderate/severe COVID-19 (25.2 compared to 9.41).

Conclusions

Covid whole-blood IGRA is a highly accurate, straightforward and robust assay and can be easily adapted to measure cellular response to COVID-19. A complete evaluation of the vaccine response may be particularly important for individuals living with immunodeficiency. A clinical immunodeficiency score and a validated vaccine response score may be valuable tools in estimating COVID-19 disease risk and identifying individuals living with immunodeficiency who may benefit from enhanced vaccination schedules.

Sex differences in the decoding of pain-related body postures

BACKGROUND

Pain can be detected through nonverbal cues, including facial expressions, vocalisations, and body posture. While there are sex differences in how emotional expressions are recognized, these differences have not always been found for pain. One reason for this inconsistency may be methodological, as pain studies tend not to be designed to investigate individual differences in expression recognition. Also, few studies consider sex differences outside facial expression.

METHODS

This study applied an image degradation method used to examine individual differences in emotion recognition, to investigate sex differences in the decoding of pain body postures. Forty participants (20 male) were presented with a series of body posture images depicting pain at differing levels of image degradation. Happiness, anger and sadness expressions were also included for comparison.

RESULTS

Results showed significant effects of image degradation, affect type, and actor sex. Females were rated as presenting more intense pain than males; this pattern was also found for fear, but not anger or happiness. The accuracy of pain intensity judgements was reduced as image clarity decreased. Male actors depicting pain were recognized with greater accuracy than female actors. Interestingly, similar patterns were found for anger and fear expressions.

CONCLUSIONS

We conclude that sex has a significant influence on pain decoding under certain conditions, and while there are similarities with the way pain and core emotions are decoded, this may depend on the type of emotion presented. This also suggests that sex-related effects in the recognition of pain expressions may include body postural cues.

SIGNIFICANCE

Observer's judgements of pain displayed through body postures are driven by the sex of the person in pain.

Rapid annotation of interictal epileptiform discharges via template matching under Dynamic Time Warping

BACKGROUND

EEG interpretation relies on experts who are in short supply. There is a great need for automated pattern recognition systems to assist with interpretation. However, attempts to develop such systems have been limited by insufficient expert-annotated data. To address these issues, we developed a system named NeuroBrowser for EEG review and rapid waveform annotation.

NEW METHODS

At the core of NeuroBrowser lies on ultrafast template matching under Dynamic Time Warping, which substantially accelerates the task of annotation.

RESULTS

Our results demonstrate that NeuroBrowser can reduce the time required for annotation of interictal epileptiform discharges by EEG experts by 20-90%, with an average of approximately 70%.

COMPARISON WITH EXISTING METHOD(S)

In comparison with conventional manual EEG annotation, NeuroBrowser is able to save EEG experts approximately 70% on average of the time spent in annotating interictal epileptiform discharges. We have already extracted 19,000+ interictal epileptiform discharges from 100 patient EEG recordings. To our knowledge this represents the largest annotated database of interictal epileptiform discharges in existence.

CONCLUSION

NeuroBrowser is an integrated system for rapid waveform annotation. While the algorithm is currently tailored to annotation of interictal epileptiform discharges in scalp EEG recordings, the concepts can be easily generalized to other waveforms and signal types.

Results of an Infection Control Survey in Ultrasound Departments and Recommended Guidelines

Prevention of disease transmission by cross infection is very important in the hospital environment to protect both staff and patients.

At the present time most hospitals have stringent infection control policies which are largely geared toward the wards, critical care units and the operating theatres but there does not appear to be specific guidelines for ultrasound departments. Considering the contact nature of the ultrasound examination and the large number of tests that are performed in most hospitals annually it was felt that this was an area that needed to be addressed. One must be aware not only of protection of patients and staff but also of care in the cleaning of expensive equipment.

We undertook a national survey of the larger general ultrasound departments, vascular and cardiac laboratories to establish current practices and to assess whether these are adequate. We also contacted a number of ultrasound companies and requested cleaning specifications for their equipment.

The full results of the survey, the biological effectiveness of different cleaning techniques and their compatibility with ultrasound transducers will be discussed. Finally, recommendations regarding safe effective cleaning procedures and sensible infection control precautions in ultrasound departments will be made.

Why go online when you have pain? A qualitative analysis of teenagers' use of the Internet for pain management advice

BACKGROUND

Adolescents are routinely recognized as native to online technologies. However, we know from previous research that this familiarity does not often translate into its use for help-seeking around health. We designed this study to examine the experience of adolescents in using the Internet to access pain management information, specifically why some adolescents may be reluctant to use these resources.

METHODS

Twenty-six healthy, school attending, adolescents aged between 14 and 17 years old were recruited to a qualitative study of focus groups. Seventeen participants were female and nine were male. Participation was limited to those who self-selected as frequent users of the Internet, but who were loath to use it as a resource for health information as we wished to explore reasons for non-use. All data were thematically analysed.

RESULTS

Most participants reported using the Internet to seek health information at least once. Experiences with online content were typically negative and drawn on only when all other sources of information and pain coping were exhausted. Three themes emerged, Drivers of Internet use, Barriers, and Anxiety around use. Adolescent health websites were reported to be confusing, anxiety provoking and hard to negotiate. The Internet was judged to be less accessible than other forms of pain and health coping information. Secondary themes related to topic embarrassment, the strive for independence and reassurance, preferred information source failure, curiosity, website design, availability of OTC analgesics, effort, fear-provoking narratives, mistrust of quality of online content and pain-related anxiety.

CONCLUSIONS

Counter to many positive reports of the health benefits of Internet use during information seeking, its value is questionable to some adolescents. Typical experience was anxiety provoking, unlikely to yield helpful results, and wasteful comparative to off-line resources for pain.

Supporting anthropological research with efficient rotation invariant shape similarity measurement

The matching of two-dimensional shapes is an important problem with many applications in anthropology. Examples of objects that anthropologists are interested in classifying, clustering and indexing based on shape include bone fragments, projectile points (arrowheads/spearpoints), petroglyphs and ceramics. Interest in matching such objects originates from the fundamental question for many biological anthropologists and archaeologists: how can we best quantify differences and similarities? This interest is fuelled in part by a movement that notes: 'an increasing number of archaeologists are showing interest in employing Darwinian evolutionary theory to explain variation in the material record'. Aiding such research efforts with computers requires a shape similarity measure that is invariant to many distortions, including scale, offset, noise, partial occlusion, etc. Most of these distortions are relatively easy to handle, either in the representation of the data or in the similarity measure used. However, rotation invariance seems to be uniquely difficult. Current approaches typically try to achieve rotation invariance in the representation of the data, at the expense of poor discrimination ability, or in the distance measure, at the expense of efficiency. In this work, we show that we can take the slow but accurate approaches and dramatically speed them up. On real world problems, our technique can take current approaches and make them four orders of magnitude faster, without false dismissals. Moreover, our technique can be used with any of the dozens of existing shape representations and with all the most popular distance measures, including Euclidean distance, dynamic time warping and longest common subsequence. We show the applications of our work to several important problems in anthropology, including clustering and indexing of skulls, projectile points and petroglyphs.

Hypoalgesic effect of caffeine in normotensive men and women

Evidence from both hypertensive and normotensive individuals indicate that elevated blood pressure is associated with decreased pain sensitivity. The current study sought to experimentally raise blood pressure using 250 mg caffeine, and investigate its effects on the cold pressor pain experiences of 25 men and 25 women. In a placebo-controlled repeated-measures experiment, caffeine increased systolic and diastolic blood pressure, as well as producing more clearheaded and energetic feelings. Caffeine produced higher pain threshold and pain tolerance levels compared to placebo, and women had a lower tolerance to pain than men. Finally, a significant association was found between caffeine-related increase in systolic blood pressure and caffeine-related increase in pain tolerance. Furthermore, this association was the strongest in women. These results are discussed in light of future directions for pain and hypertension research.

Investigating the effects of anxiety sensitivity and coping on the perception of cold pressor pain in healthy women

Research indicates that anxiety sensitivity may be related to the negative experience of pain, especially amongst women. Further evidence with chronic pain patients indicates that anxiety sensitivity may result in avoidance pain-coping strategies. However, this effect has not yet been experimentally investigated in healthy groups. Therefore, the current study sought to investigate the effect of anxiety sensitivity and coping on women's responses to pain. Thirty women who were classified as high in anxiety sensitivity and 30 women classified as low in anxiety sensitivity participated. Within each anxiety sensitivity group, half the participants (n = 15) were randomly instructed to either focus on or avoid cold pressor pain sensations. As expected, women high in anxiety sensitivity were found to report higher levels of sensory and affective pain. Also, and consistent with previous research into anxiety sensitivity, no differences were found between anxiety sensitivity groups for measures of pain threshold or pain tolerance. The pain coping instruction manipulation was found to moderate pain experience, in that the avoidance strategy resulted in higher pain ratings compared to when instructed to focus. Finally, high anxiety sensitive women reported greater pain when instructed to avoid rather than focus on cold pressor pain. These results are discussed in light of previous research and future directions for pain management.

Identification of new epitopes from four different tumor-associated antigens: recognition of naturally processed epitopes correlates with HLA-A*0201-binding affinity

Forty-two wild-type and analogue peptides derived from p53, carcinoembryonic Ag, Her2/neu, and MAGE2/3 were screened for their capacity to induce CTLs, in vitro, capable of recognizing tumor target lines. All the peptides bound HLA-A*0201 and two or more additional A2 supertype alleles with an IC(50) of 500 nM or less. A total of 20 of 22 wild-type and 9 of 12 single amino acid substitution analogues were found to be immunogenic in primary in vitro CTL induction assays, using normal PBMCs and GM-CSF/IL-4-induced dendritic cells. These results suggest that peripheral T cell tolerance does not prevent, in this system, induction of CTL responses against tumor-associated Ag peptides, and confirm that an HLA class I affinity of 500 nM or less is associated with CTL epitope immunogenicity. CTLs generated by 13 of 20 of the wild-type epitopes, 6 of 9 of the single, and 2 of 5 of the double substitution analogues tested recognized epitopes generated by endogenous processing of tumor-associated Ags and expressed by HLA-matched cancer cell lines. Further analysis revealed that recognition of naturally processed Ag was correlated with high HLA-A2.1-binding affinity (IC(50) = 200 nM or less; p = 0.008), suggesting that high binding affinity epitopes are frequently generated and can be recognized as a result of natural Ag processing. These results have implications for the development of cancer vaccines, in particular, and for the process of epitope selection in general.

Selective attentional biases for physical threat in physical anxiety sensitivity

Anxiety sensitivity is a trait susceptibility associated with the fear of anxiety-related sensations. One reason why such fears exist may be because those high in anxiety sensitivity selectively attend towards such sensations. However, few studies have actually investigated these cognitive biases in high anxiety sensitive individuals. The current study, therefore, sought to investigate selective attentional biases using the visual dot-probe paradigm. Since recent research suggests that at least one component of anxiety sensitivity is linked to the fear of physical sensations, individual were selected on the basis as to whether they were high or low in their anxious concern for physical sensations. In order to determine whether a general or specific attentional bias exists, the emotionality of material presented to participants was varied in terms of whether it was physically threat-related, socially threat-related, or positive. Consistent with predictions, those high in physical anxiety sensitivity were found to exhibit a selective attentional bias in favour of the location of physically threatening material. Furthermore, those low in anxiety sensitivity were found to avoid such material. Interestingly, a similar attentional bias was not found for either socially threatening or positive material. If anything, those high in physical anxiety sensitivity avoided positive material. These findings are discussed in light of current theories of anxiety sensitivity and future research.

Selective attentional bias for pain-related stimuli amongst pain fearful individuals

Recent research indicates that people who are fearful of pain tend to report more negative pain experiences. It also seems that attentional mechanisms may be particularly important in the perception of painful stimuli, especially amongst pain fearful individuals. Drawing on a paradigm used to examine biased cognitive processes in the emotional disorders, the current study investigated whether the fear of pain would be related to a greater selective attentional bias in favour of pain-related stimuli. In order to determine the nature of this bias, stimuli material were varied in terms of whether they were related to pain sensations, were related to socially threatening situations or were relatively positive. Those with a high fear of pain exhibited a selective attentional bias towards pain-related information, compared to those classified as low in the fear of pain. No group differences were found for either social threat or positive stimuli. These results indicate that one reason why those with a high fear of pain are particularly susceptible to negative pain experiences could be due to biased attentional processes. Suggestions for cognitive interventions designed to reduce such biases are discussed, as are directions for future research.

Social competition in school: relationships with bullying, Machiavellianism and personality

BACKGROUND

Bullying is investigated as part of the individual's general framework of attitudes towards interpersonal relationships, social competition and motivation in school.

AIMS

It was hypothesised that bullying behaviour and pro-bullying attitudes would be associated with socially competitive attitudes in the classroom, Machiavellianism, and the personality constructs of Psychoticism and Extraversion.

SAMPLES

198 9- to 12-year-old children from two Glasgow primary schools.

METHODS

Children completed several measures: a newly developed questionnaire assessing motivations behind social competition and effort in class, the Kiddie-Mach scale, the Pro-Victim scale, items from the Olweus Bullying Questionnaire, and the Junior Eysenck Personality Questionnaire.

RESULTS

A 'Desire for social success' factor (incorporating a deliberate lack of effort) was negatively correlated with support for victims of bullying, even after partialling out Machiavellianism, Psychoticism, and social desirability. Pro-victim attitudes were in turn negatively correlated with Machiavellianism and Psychoticism, and positively correlated with Lie score. Finally, children categorised as bullies scored significantly higher than controls on Machiavellianism, and significantly lower in terms of pro-victim attitudes.

CONCLUSIONS

Results are discussed in terms of further study and implications for classroom practice and anti-bullying policy.

Avoidance versus focused attention and the perception of pain: differential effects for men and women

The aim of the current investigation was to compare the effects of two different attentional strategies (focused vs. avoidance) on how males and females respond to experimentally induced pain. One hundred healthy adults were instructed to either attend towards or away from cold pressor pain. Measures of pain tolerance, pain threshold and recovery were taken, as were self-report measures of sensory and affective pain experiences. As expected, gender was found to moderate tolerance to pain: males were found to be more tolerant to cold pressor pain than females. With respect to the self-report measures, males reported less sensory pain when they attended toward the pain than when they avoided it. However, a similar effect was not found in women, suggesting that attentional focusing may only be a useful strategy for males. These results are discussed in light of previous research.

Exploring the factor structure of the Mood and Anxiety Symptom Questionnaire (MASQ)

L. A. Clark and Watson (1991) proposed a tripartite model of anxiety and depression defined in terms of common symptoms relating to general distress, anxiety-specific symptoms of hyperarousal, and depression-specific symptoms of low positive affect and loss of interest. To aid the measurement of and discrimination between anxiety and depression they developed the Mood and Anxiety Symptom Questionnaire (MASQ). Although potentially useful, the MASQ is still in an early stage of development, and there is an indication that a discrepancy exists between items and scales. Therefore, the aim of this study was to explore the items and factors of the MASQ and determine whether a pattern similar to that suggested by L. A. Clark and Watson would emerge. Factor analysis of the MASQ revealed 3 factors relating to general distress, positive affect, and anxious arousal. Inspection of the individual items indicated that some refinements are required.

Manic-depressiveness and its correlates

Manic-depressiveness is the name here given to a hypothesized personality continuum that has, at one extreme, manic-depressive psychosis. A Manic-Depressiveness Scale is described, which comprises three scales, Manic Experience, Depressive Experience, and the sum of the two, since they are correlated. 250 undergraduate psychology students at the University of Adelaide and at Goldsmiths' College, London, were administered the Manic-Depressiveness Scale along with 12 measures including the Eysenck Personality Questionnaire (Revised). Scores on the total Manic-Depressiveness Scale tended (in order of size of association) to be correlated with Schizotypal Personality (and three subscales), Neuroticism, Magical Ideation, Mystical Experience, Belief in the Paranormal, absence of Social Naïveté, and Psychoticism. Manic Experience showed a pattern of relationships with the above variables broadly similar to that of Depressive Experience but included Creative Personality, while Depressive Experience included introversion. The relationship between manic-depressiveness and schizotypy is discussed.

Self-Deceptive Enhancement and Impression Management correlates of EPQ-R dimensions

The Self-Deceptive Enhancement and Impression Management scales of the Paulhus (1991) Balanced Inventory of Desirable Responding were correlated with the Psychoticism, Neuroticism, Extraversion, and Lie scales of the Eysenck EPQ-R (Eysenck & Eysenck, 1991) in a student sample. Extraversion correlated positively and Neuroticism correlated negatively with Self-Deceptive Enhancement, whereas Psychoticism correlated negatively and the Lie scale correlated positively with Impression Management. These findings suggest that the EPQ-R scales are involved in different aspects of socially desirable responding. It was concluded that social desirability should not be controlled in measures of Extraversion and Neuroticism but it should be controlled in measures of Psychoticism.

In vitro immunization and expansion of antigen-specific cytotoxic T lymphocytes for adoptive immunotherapy using peptide-pulsed dendritic cells

The design of an effective procedure to sensitize and expand antigen-specific cytotoxic T lymphocytes (CTL) in vitro is essential for the development of effective adoptive cellular immunotherapy protocols for cancer. We have analyzed the capacity of tissue culture-derived dendritic cells (DC) to present specific peptide epitopes to CTL precursors. Our results demonstrate that peptide-pulsed DC were efficient in generating CTL responses specific for various viral and tumor epitopes. Furthermore, IL-7 and IL-10 potentiated the ability of the peptide-pulsed DC to trigger antigen-specific CTL responses. The CTL generated using this procedure efficiently recognized the naturally processed antigens and could be expanded approximately 100- to 1000-fold in tissue culture in 10 to 15 days without a loss of activity and specificity. The results and procedures described herein may facilitate the development of effective CTL-based adoptive immunotherapy for chronic viral diseases and cancer.

Derivation of HLA-A11/Kb transgenic mice: functional CTL repertoire and recognition of human A11-restricted CTL epitopes

Transgenic mice expressing chimeric human (alpha1 and alpha2 HLA-A11 domains) and murine (alpha3, transmembrane, and cytoplasmic H-2Kb domains) class I molecules were derived. These mice were used as a model system to study the immunogenicity of human CTL epitopes and also to examine the aspects of Ag processing differences of mice vs man. Immunization of these mice with seven known HLA-A11-restricted CTL epitopes emulsified in IFA resulted in vigorous specific CTL responses. A larger panel of 45 A11-binding peptides was used to examine the relationship between immunogenicity in the HLA-A11/Kb transgenic mice and HLA-A11 binding capacity. Twenty-one of 28 (75%) peptides with high binding affinities (50% inhibitory concentration (IC50), 2-50 nM) and 7 of 13 (54%) intermediate binding peptides (IC50, 50-500 nM range) were immunogenic. In parallel, 19 of these peptides were used for in vitro primary immunizations of PBMC derived from HLA-A11 healthy human donors. It was found that 8 of 8 peptides that were able to elicit CTL in primary human in vitro cultures were also immunogenic in HLA-A11/Kb mice. Finally, HLA-A11/Kb transgenic mice were found to generate an A11/Kb restricted CTL response following immunization with influenza virus A/PR/8/34, suggesting that, at least to some extent, A11 epitopes are generated by transgenic mice as a result of natural in vivo processing and presentation.

Derivation of HLA-A11/Kb transgenic mice: functional CTL repertoire and recognition of human A11-restricted CTL epitopes

Transgenic mice expressing chimeric human (alpha1 and alpha2 HLA-A11 domains) and murine (alpha3, transmembrane, and cytoplasmic H-2Kb domains) class I molecules were derived. These mice were used as a model system to study the immunogenicity of human CTL epitopes and also to examine the aspects of Ag processing differences of mice vs man. Immunization of these mice with seven known HLA-A11-restricted CTL epitopes emulsified in IFA resulted in vigorous specific CTL responses. A larger panel of 45 A11-binding peptides was used to examine the relationship between immunogenicity in the HLA-A11/Kb transgenic mice and HLA-A11 binding capacity. Twenty-one of 28 (75%) peptides with high binding affinities (50% inhibitory concentration (IC50), 2-50 nM) and 7 of 13 (54%) intermediate binding peptides (IC50, 50-500 nM range) were immunogenic. In parallel, 19 of these peptides were used for in vitro primary immunizations of PBMC derived from HLA-A11 healthy human donors. It was found that 8 of 8 peptides that were able to elicit CTL in primary human in vitro cultures were also immunogenic in HLA-A11/Kb mice. Finally, HLA-A11/Kb transgenic mice were found to generate an A11/Kb restricted CTL response following immunization with influenza virus A/PR/8/34, suggesting that, at least to some extent, A11 epitopes are generated by transgenic mice as a result of natural in vivo processing and presentation.

Degenerate and promiscuous recognition by CTL of peptides presented by the MHC class I A3-like superfamily: implications for vaccine development

Recent data demonstrate that HLA class I alleles can be grouped into superfamilies based on similarities of their peptide-binding motifs. In this study, we have tested the immunogenicity and antigenicity of peptides capable of degenerate binding to multiple HLA class I molecules of the A3-like superfamily. The assay systems utilized included both primary in vitro cultures of lymphocytes from healthy donors, as well as in vitro restimulation of lymphocytes from HIV-infected individuals. Several of the peptides capable of binding more than one HLA A3-like class I molecule were also found to be immunogenic in the context of this same group of A3-like molecules (degenerate CTL recognition). Furthermore, some of the CTL lines thus generated demonstrated promiscuous recognition of the cognate epitope in the context of MHC molecules from more than one member of the superfamily. The fine Ag specificity of this phenomenon was further analyzed using two promiscuous CTL clones derived from A3 and A11 individuals, respectively, and specific for an epitope in the HIV-1 reverse transcriptase. By the use of single-amino acid-substitution analogues, it was demonstrated that the fine specificity of the TCR is largely maintained between MHC-matched and MHC-mismatched presentation of peptide within the A3-like superfamily. These results indicate that the similar peptide-binding specificities among different members of the A3-like superfamily can be reflected in a remarkable similarity in the peptide-MHC complex structures engaged by the TCR and responsible for T cell activation.

Degenerate and promiscuous recognition by CTL of peptides presented by the MHC class I A3-like superfamily: implications for vaccine development

Recent data demonstrate that HLA class I alleles can be grouped into superfamilies based on similarities of their peptide-binding motifs. In this study, we have tested the immunogenicity and antigenicity of peptides capable of degenerate binding to multiple HLA class I molecules of the A3-like superfamily. The assay systems utilized included both primary in vitro cultures of lymphocytes from healthy donors, as well as in vitro restimulation of lymphocytes from HIV-infected individuals. Several of the peptides capable of binding more than one HLA A3-like class I molecule were also found to be immunogenic in the context of this same group of A3-like molecules (degenerate CTL recognition). Furthermore, some of the CTL lines thus generated demonstrated promiscuous recognition of the cognate epitope in the context of MHC molecules from more than one member of the superfamily. The fine Ag specificity of this phenomenon was further analyzed using two promiscuous CTL clones derived from A3 and A11 individuals, respectively, and specific for an epitope in the HIV-1 reverse transcriptase. By the use of single-amino acid-substitution analogues, it was demonstrated that the fine specificity of the TCR is largely maintained between MHC-matched and MHC-mismatched presentation of peptide within the A3-like superfamily. These results indicate that the similar peptide-binding specificities among different members of the A3-like superfamily can be reflected in a remarkable similarity in the peptide-MHC complex structures engaged by the TCR and responsible for T cell activation.

Degenerate cytotoxic T cell epitopes from P. falciparum restricted by multiple HLA-A and HLA-B supertype alleles

We recently described human leukocyte antigen (HLA) A2, A3 and B7 supertypes, characterized by largely overlapping peptide-binding specificities and represented in a high percentage of different populations. Here, we identified 17 Plasmodium falciparum peptides capable of binding these supertypes and assessed antigenicity in both vaccinated and naturally exposed populations. Positive cytotoxic T lymphocyte recall and cytokine (interferon-gamma and tumor necrosis factor alpha) responses were detected for all peptides; all were recognized in the context of more than one HLA class I molecule; and at least 12 of the 17 were recognized in the context of all HLA alleles studied. These data validate the concept of HLA supertypes at the biological level, show that highly degenerate peptides are almost always recognized as epitopes, and demonstrate the feasibility of developing a universally effective vaccine by focusing on a limited number of peptide specificities.

Identification of A2-restricted hepatitis C virus-specific cytotoxic T lymphocyte epitopes from conserved regions of the viral genome

We have focused on conserved regions of the hepatitis C Virus (HCV) genome to identify viral peptides that contain HLA class I binding motifs and bind with high affinity to the corresponding purified HLA molecules. Accordingly, we have identified 31 candidate epitopes in the HCV that have the potential to be recognized by either HLA-A1, A2.1-, A3, A11- or A24-restricted cytotoxic T lymphocytes (CTL). Twelve conserved peptides that bind HLA-A2.1 with high or intermediate affinity were tested for immunogenicity in vitro in human primary CTL cultures and in vivo by direct immunization of HLA-A2.1/Kb transgenic mice. Six HLA-A2.1-restricted CTL epitopes were immunogenic in both systems. At least three of these peptide epitopes were endogenously processed and presented for CTL recognition. Overall, these data illustrate the value of this approach for the development of virus-specific, peptide-based vaccines.

Differences and similarities in the A2.1-restricted cytotoxic T cell repertoire in humans and human leukocyte antigen-transgenic mice

HLA-A2.1-binding peptides (n = 38) were screened for immunogenicity with human peripheral blood mononuclear cells in cytotoxic T lymphocyte (CTL) induction experiments in vitro and with splenocytes from HLA-A2.1/Kb transgenic mice following immunization in vivo. These data were compiled and analyzed to determine the level of overlap between the A2.1-restricted CTL repertoire of A2.1/Kb-transgenic mice and A2.1+ humans. In both humans and mice, a major histocompatibility complex affinity threshold of approximately 500 nM appears to determine the capacity of a peptide to elicit a CTL response. Good concordance between the human data in vitro and mouse data in vivo was observed with 85% of the high-binding peptides, 58% of the intermediate binders, and 83% of the low/negative binders. Although some peptides immunogenic for mouse CTL but not for humans (and vice versa) could be identified, the data as a whole suggest an extensive overlap between T cell receptor repertoires of mouse and human CTL and support the use of HLA-transgenic mice for the identification of potential human CTL epitopes.

Factor VII, antithrombin III, leukocyte and platelet counts in a sample of black and white Zimbabwean blood donors

Studies in Southern Africa have shown that whites have significantly greater morbidity and mortality from coronary heart disease than blacks. This study investigated the distribution of some haemostatic variables known or suspected to be correlated with greater risk for coronary heart disease in healthy black and white Zimbabwean men. Factor VII, antithrombin III, leukocyte and platelet counts were measured in 56 blacks and 29 whites aged between 20 and 50 years. We found significantly greater factor VII and leukocyte counts in the whites compared to the blacks. The other variables measured were similar in the two ethnic groups. These results suggest that the greater prevalence of coronary heart disease in whites is consistent with high levels of factor VII and white blood cell counts previously identified as risk factors for this condition.

African neutropaenia in Zimbabwe

The distribution of total and differential leucocyte counts in a sample of Black and White Zimbabwean men living in the same environment was determined. White Zimbabweans had significantly higher total leucocyte counts than Black Zimbabweans and the difference was due to the significantly lower neutrophil counts in the Blacks. It was concluded that genetically determined "African neutropaenia" exists in Zimbabwe.

The sites of action of estradiol and phentolamine in the inhibition of the pulsatile, circhoral discharges of LH in the rhesus monkey (Macaca mulatta)

Pulsatile LH secretion was re-established in ovariectomized monkeys bearing hypothalamic lesions by an intermittent infusion of LHRH. The administration of estradiol to such animals resulted in a prompt cessation of these pulsatile discharges of LH and a resultant decline in the mean plasma concentration of the gonadotropin. The time course of this inhibition of LH secretion was indistinguishable from that observed after estrogen administration to ovariectomized animals with intact nervous systems. In contrast, phentolamine did not interrupt the pulsatile LH discharges occasioned by the hourly administration of exogenous LHRH to the lesioned animals. These results are consistent with the conclusion that the acute negative feedback action of estradiol on circhoral LH release in the monkey is at the level of the pituitary gland, whereas the inhibitory action of phentolamine on this mode of LH secretion is at a neural site.