Response Of Normal Individuals Research Articles

Polyclonal Expansion of NKG2C(+) NK Cells in TAP-Deficient Patients.

Adaptive natural killer (NK) cell responses to human cytomegalovirus infection are characterized by the expansion of NKG2C+ NK cells expressing self-specific inhibitory killer-cell immunoglobulin-like receptors (KIRs). Here, we set out to study the HLA class I dependency of such NKG2C+ NK cell expansions. We demonstrate the expansion of NKG2C+ NK cells in patients with transporter associated with antigen presentation (TAP) deficiency, who express less than 10% of normal HLA class I levels. In contrast to normal individuals, expanded NKG2C+ NK cell populations in TAP-deficient patients display a polyclonal KIR profile and remain hyporesponsive to HLA class I-negative target cells. Nonetheless, agonistic stimulation of NKG2C on NK cells from TAP-deficient patients yielded significant responses in terms of degranulation and cytokine production. Thus, while interactions with self-HLA class I molecules likely shape the KIR repertoire of expanding NKG2C+ NK cells during adaptive NK cell responses in normal individuals, they are not a prerequisite for NKG2C+ NK cell expansions to occur. The emergence of NKG2C-responsive adaptive NK cells in TAP-deficient patients may contribute to antiviral immunity and potentially explain these patients’ low incidence of severe viral infections.

Distinct Patterns and Magnitude Of T Cell Responses Are Associated With Seasonal Exposure To Timothy Grass Allergens

RationaleTimothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. Our overall goal is to characterize TG-specific T-cell responses as a function of disease severity and also as a function of seasonality. We are further interested in assessing the quantitative differences, in terms of magnitude of the response, but also qualitative differences, in the type of T-cell subsets (TH) involved.MethodsPBMCs samples obtained either during the pollen season or out-of-season, from allergic and non-allergic controls were stimulated either with TG extract or a pool of the 20 previously identified antigenic regions. The production of lymphokines associated with different TH subsets was evaluated.ResultsAs expected, in PBMC samples obtained in-season, the cytokine production was higher in allergic donors as compared to out-of-season, for IFNg, IL-5, IL-10 and IL-17. Memory cells gave a more robust lymphokine response in-season in allergics. In the case of non-allergic individuals, we observed much lower responses in terms of the Th2 associated cytokine IL5, and expected a robust production of Th1-associated IFNg. Strikingly the Th1 responses in normal individuals were decreased in-season when compared to out-of-season. The potential basis of this phenomenon is currently being investigated. It is possible that this phenomenon might reflect differences in tissue homing or in-season allergen stimulation resulting in activation of regulatory cells/mechanisms in non-allergic individuals.ConclusionsOur data suggest that the magnitude and functionality of TH responses differ substantially for in-season versus out-of-season in allergic and non-allergic individuals. RationaleTimothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. Our overall goal is to characterize TG-specific T-cell responses as a function of disease severity and also as a function of seasonality. We are further interested in assessing the quantitative differences, in terms of magnitude of the response, but also qualitative differences, in the type of T-cell subsets (TH) involved. Timothy grass (TG) pollen is a common seasonal airborne allergen associated with symptoms ranging from mild rhinitis to severe asthma. Our overall goal is to characterize TG-specific T-cell responses as a function of disease severity and also as a function of seasonality. We are further interested in assessing the quantitative differences, in terms of magnitude of the response, but also qualitative differences, in the type of T-cell subsets (TH) involved. MethodsPBMCs samples obtained either during the pollen season or out-of-season, from allergic and non-allergic controls were stimulated either with TG extract or a pool of the 20 previously identified antigenic regions. The production of lymphokines associated with different TH subsets was evaluated. PBMCs samples obtained either during the pollen season or out-of-season, from allergic and non-allergic controls were stimulated either with TG extract or a pool of the 20 previously identified antigenic regions. The production of lymphokines associated with different TH subsets was evaluated. ResultsAs expected, in PBMC samples obtained in-season, the cytokine production was higher in allergic donors as compared to out-of-season, for IFNg, IL-5, IL-10 and IL-17. Memory cells gave a more robust lymphokine response in-season in allergics. In the case of non-allergic individuals, we observed much lower responses in terms of the Th2 associated cytokine IL5, and expected a robust production of Th1-associated IFNg. Strikingly the Th1 responses in normal individuals were decreased in-season when compared to out-of-season. The potential basis of this phenomenon is currently being investigated. It is possible that this phenomenon might reflect differences in tissue homing or in-season allergen stimulation resulting in activation of regulatory cells/mechanisms in non-allergic individuals. As expected, in PBMC samples obtained in-season, the cytokine production was higher in allergic donors as compared to out-of-season, for IFNg, IL-5, IL-10 and IL-17. Memory cells gave a more robust lymphokine response in-season in allergics. In the case of non-allergic individuals, we observed much lower responses in terms of the Th2 associated cytokine IL5, and expected a robust production of Th1-associated IFNg. Strikingly the Th1 responses in normal individuals were decreased in-season when compared to out-of-season. The potential basis of this phenomenon is currently being investigated. It is possible that this phenomenon might reflect differences in tissue homing or in-season allergen stimulation resulting in activation of regulatory cells/mechanisms in non-allergic individuals. ConclusionsOur data suggest that the magnitude and functionality of TH responses differ substantially for in-season versus out-of-season in allergic and non-allergic individuals. Our data suggest that the magnitude and functionality of TH responses differ substantially for in-season versus out-of-season in allergic and non-allergic individuals.

Patterns in the parathyroid response to sodium bicarbonate infusion test in healthy volunteers.

Background. The sodium bicarbonate infusion test evaluates the function of the parathyroid glands. The present study aims to evaluate the range of parathyroid response in healthy individuals and the potential influence of various factors. Methods. Fifty healthy volunteers were subjected to the test. Levels of vitamin D, calcium, albumin, and PTH were measured before infusion. PTH was measured at 3, 5, 10, 30, and 60 minutes after infusion. Results. A curve describing the response of parathyroids to the test was drawn. Twenty percent of the subjects had blunted PTH response. No significant difference was observed between normal and blunted responders concerning age, BMI, baseline PTH, or calcium levels. Nonetheless, there was a significant difference in vitamin D levels (P = 0.024). Interpretation. The test is easy to perform and may be used for everyday screening. It has to be clarified whether our observations are, at least partly, produced due to the presence of individuals with a constitutively blunted response or if low levels of vitamin D decrease the ability of the parathyroids to respond. Whichever the case, PTH response of normal individuals to sodium bicarbonate infusion test is more varied than previously thought and vitamin D levels influence it.

Energy-saving lamps and their impact on photosensitive and normal individuals

A preliminary investigation showed that ultraviolet radiation (UVR) emissions from compact fluorescent lamps (CFLs) can pose a risk to the skin of photosensitive individuals. To carry out a larger-scale study, in patients with a range of photodermatoses, to assess this risk. To determine a safe alternative light source for photosensitive individuals. To investigate if CFL emissions have the potential to induce skin responses in normal individuals. Two hundred patients were directly exposed to a single-envelope CFL as part of their routine management. Irradiation was carried out on the inner forearm with lamps positioned at 5cm. Skin assessments were made immediately and 24h postirradiation. Eleven of these patients were further tested to a double-envelope CFL. One hundred and one patients were tested to emissions from a light-emitting diode (LED). A study involving 20 healthy individuals was carried out with exposure to the single-envelope CFL. Skin erythema was induced by the single-envelope CFL in the following cases: 16 of 53 chronic actinic dermatitis, seven of 52 polymorphic light eruption, five of nine solar urticaria, one of two actinic prurigo, one of one erythropoietic protoporphyria and two of 20 healthy subjects. The double-envelope CFL eliminated or reduced the skin response in all 11 patients tested. The LED did not induce any UVR-provoked skin responses. UVR from CFLs can aggravate the skin of photosensitive and healthy individuals when situated in close proximity. Double-envelope lamps reduce this risk. LEDs offer a safer alternative light source that eliminates the risk of UVR-induced skin erythema.

Vestibular Electrical Evoked Potential (VEEP) Findings in Normal Controls and in Patients with Vestibular Dysfunction (P02.251)

Objective: To report results of human VEEP studies in normal controls compared to patients with peripheral or central vestibular dysfunction. Background The VEEP has been described in animal models (cat and guinea pig) and more recently in humans. In contrast to other evoked potentials, a unique linear relationship between current strength and latency has been reported with VEEP responses in normal individuals. Design/Methods: Normal control subjects (n=5) and patients with vestibular dysfunction (n=3) were studied with electrical stimulation over the mastoid in one mA increments from threshold to no higher than 20 mA. Evoked potentials were recorded with standard signal averaging techniques. Results: In normal controls, mastoid stimulation at 2.5mA yielded Cz-A1/2 VEEP responses of median latency 10.2ms (range 6.0-13.3; SD 4.9). These responses progressively increased in latency from 8.6 to 22.6ms (mean latency increase of 1.3ms/mA) as current strength was increased in 10 steps (1mA/step) from threshold. VEEP responses differed significantly in stimulation threshold, morphology, amplitude and latency from mastoid dermatomal somatosensory evoked potentials (SEPs), great auricular sensory nerve action potentials (SNAPs), and frontalis compound muscle action potentials (CMAPs). Neither acoustic stimuli nor white noise masking affected the VEEP. In 3 patients with vestibular dysfunction (one each with acoustic neuroma, Meniere disease and multiple sclerosis as the cause) VEEP late response latencies were absent or markedly asymmetric, with recordable responses showing a median latency of 12.2ms (range 11.2-12.7; SD 0.4); none demonstrated the linear increasing current strength-latency pattern seen in normals. Conclusions: 1) VEEP studies produced reproducible responses in normal controls; 2) VEEP responses cannot be attributed to auditory or somatic sensory nerve responses; 3) VEEP current strength-latency curves showed a linear increase in normals in contrast to absent, flat, and/or decreasing patterns in patients with vestibular dysfunction. Supported by: Mayo Foundation. Disclosure: Dr. Smith has nothing to disclose. Dr. Cevette has nothing to disclose. Dr. Stepanek has nothing to disclose. Dr. Cocco has nothing to disclose. Dr. Pradhan has nothing to disclose. Dr. Brookler has nothing to disclose. Dr. Zapala has nothing to disclose. Dr. Ross has nothing to disclose.

Out of a Cell into This Darkened Space

Out of a Cell into This Darkened Space

Comparison of four laboratory methods to assess aspirin sensitivity

The purpose of this study was to compare the ability of four commercial platelet function assays to detect aspirin response in normal individuals taking 81 or 325 mg aspirin in a single-dose response and then in a 7-day dosing regimen. We employed the Chronolog 570VS whole-blood aggregometer with agonists 1.0 microgram/ml collagen and 0.5 mmol/l arachidonic acid, the PFA-100 epinephrine/collagen cartridge closure time, the Accumetrics Verify/Now arachidonic acid cartridge, and the urine 11-dehydrothromboxane immunoassay normalized to urine creatinine. Fifty normal individuals who met the inclusion criteria were consented in the single-dose study. Blood and urine were collected at baseline, and then each participant was given a 81 mg enteric-coated aspirin tablet. Blood and urine were collected after 24 h. After a minimum of 14 days the process was repeated with a 325 mg aspirin dose. Forty-five individuals were enrolled in the 7-day study. Blood and urine were collected at baseline. Then each participant was given an 81 mg dose of aspirin daily for 7 days. After 7 days, blood and urine specimens were obtained and tested. After a minimum washout period of 14 days the process was repeated using a 7-day regimen of 325 mg enteric-coated aspirin tablet. Student's t-test indicated statistical significance between baseline and post responses in both dosing regimens (P < 0.05). Individuals were not consistently identified as aspirin responsive across all platforms. All assays discriminated between platelet response and nonresponse to aspirin at both dosages. It may be necessary to employ multiple assays to detect individual platelet response.

CD4+ T-cell recognition of human 5T4 oncofoetal antigen: implications for initial depletion of CD25+ T cells.

The human 5T4 (h5T4) oncofoetal antigen is expressed by a wide variety of human carcinomas including colorectal, ovarian, gastric and renal, but rarely on normal tissues. Its restricted expression on tumour tissues as well as its association with tumour progression and bad prognosis has driven the development of a MVA-based vaccine (TroVax) which has been tested in several early phase clinical trials and these studies have led to the start of a phase III trial in renal cell carcinoma patients. We have recently shown that CD8(+) T cells recognizing h5T4 can be generated in the absence of CD4(+) T cells from peripheral blood lymphocytes of human healthy individuals. We report the existence and expansion of human CD4(+) T cells against h5T4 by stimulation with autologous monocyte-derived dendritic cells infected with a replication defective adenovirus encoding the h5T4 cDNA (Ad-h5T4). The h5T4-specific T-cell responses in normal individuals are enhanced by initial depletion of CD25(+) cells (putative T regulatory cells) prior to the in vitro stimulation. We have identified a novel h5T4-derived 15-mer peptide recognized by CD4(+) T cells in HLA-DR4 positive healthy individuals. Interestingly, CD4(+) T cells spontaneously recognizing a different 5T4 epitope restricted by HLA-DR were identified in tumour-infiltrating lymphocytes isolated from a regressing renal cell carcinoma lung metastasis. Our data show that CD4(+) T cells recognizing h5T4 can be expanded and detected in healthy individuals and a renal cell carcinoma patient. Such h5T4-specific CD4(+) T cells boosted or induced by vaccination could act to modulate both cell or antibody mediated anti-tumour responses.

And the winner is … 20 years of excellence in research on allergic disease!

And the winner is … 20 years of excellence in research on allergic disease!

The continuing HIV vaccine saga: is a paradigm shift necessary?

As pointed out in previous editorials, the development of an effective vaccine for the Human Immunodeficiency Virus capable of preventing infection, or even one capable of preventing the Acquired Immunodeficiency Disease Syndrome, has eluded investigators for the past 20 years. Now Reche and Keskin and their co-workers have provided evidence that an entirely new approach, based upon modern bioinformatics methods and skillful in vitro immunological experiments, may result in an effective way to prime the T cell immune response of normal individuals against conserved peptide epitopes.

Identification of Novel MHC Class I and Class II Epitopes of WT1 Using a Peptide Library Screen.

Although several HLA-A*0201-restricted immunodominant peptides from the leukemia-restricted protein WT-1 are characterized, T cell responses to peptide sequences binding to other common class I and II epitopes of WT-1 remain almost completely unexplored. A more comprehensive definition of the WT-1 antigen would extend peptide antigen vaccines to individuals lacking HLA-A*0201 and *2402 and improve vaccine potency by recruiting both CD4+ and CD8+ T cell responses. Here we used a WT1 peptide library to identify WT-1 peptide sequences inducing CD4+ and CD8+ T cell responses in normal individuals and patients with AML and other myeloid leukemias. Six cases were studied. The library consisted of 110 15mer peptides overlapping by 11aa covering the entire WT-1 protein in 21 pools. Monocytes were isolated by plastic adherence and pulsed with peptide pools for 3 hours. Autologous CD8+ and CD4+ T cells were then added. Pools of peptides were prepared in such a way that each peptide was represented in two different peptide pools, allowing the identification of the respective peptide by responses in the two corresponding pools. Cells were harvested for RNA extraction and reverse transcription. Real time PCR (RQ-PCR) was used to identify peptide-specific induction of IFN-γ and IL-2 in CD8+ and CD4+ T cells. The SYFPEITHI binding motif software was then used to predict the probable HLA restriction for the candidate epitopes. To confirm candidate peptide immunogenecity and HLA restriction, selected peptides were synthesized and tested individually. In addition to the known HLA-A*0201 peptides WT37, WT126, WT187 and WT235 we identified 20 new MHC class I and II epitopes of WT1. Four were restricted by more than one HLA allele, demonstrating the promiscuity of epitope binding. One epitope (VPGVAPTLV) was restricted to HLA-A*0201 and HLA-B*5101. One epitope (SGQFTGTAGACRYGP) was restricted by a class I HLA allele, namely HLA-*6801 and a class II HLA allele, DR*1501. Two epitopes (YGPFGPPPPSQASGQ and QKKFARSDELVRHHN) were restricted by multiple MHC class II alleles. The proliferative response of CD4+ and CD8+ T cells to candidate peptides was confirmed using CFSE labeling. We now plan to characterize the antileukemic effects of CD4+ and CD8+ T cells induced by these peptides with a view to designing broad-spectrum vaccines inducing leukemia-reactive T cells across a wide range of HLA types.

Mannose-binding Lectin (MBL) Mutants Are Susceptible to Matrix Metalloproteinase Proteolysis: POTENTIAL ROLE IN HUMAN MBL DEFICIENCY

Mannose-binding lectin (MBL) plays a critical role in innate immunity. Point mutations in the collagen-like domain (R32C, G34D, or G37E) of MBL cause a serum deficiency, predisposing patients to infections and diseases such as rheumatoid arthritis. We examined whether MBL mutants show enhanced susceptibility to proteolysis by matrix metalloproteinases (MMPs), which are important mediators in inflammatory tissue destruction. Human and rat MBL were resistant to proteolysis in the native state but were cleaved selectively within the collagen-like domain by multiple MMPs after heat denaturation. In contrast, rat MBL with mutations homologous to those of the human variants (R23C, G25D, or G28E) was cleaved efficiently without denaturation in the collagen-like domain by MMP-2 and MMP-9 (gelatinases A and B) and MMP-14 (membrane type-1 MMP), as well as by MMP-1 (collagenase-1), MMP-8 (neutrophil collagenase), MMP-3 (stromelysin-1), neutrophil elastase, and bacterial collagenase. Sites and order of cleavage of the rat MBL mutants for MMP-2 and MMP-9 were: Gly(45)-Lys(46) --> Gly(51)-Ser(52) --> Gly(63)-Gln(64) --> Asn(80)-Met(81) which differed from that of MMP-14, Gly(39)-Leu(40) --> Asn(80)-Met(81), revealing that the MMPs were not functionally interchangeable. These sites were homologous to those cleaved in denatured human MBL. Hence, perturbation of the collagen-like structure of MBL by natural mutations or by denaturation renders MBL susceptible to MMP cleavage. MMPs are likely to contribute to MBL deficiency in individuals with variant alleles and may also be involved in clearance of MBL and modulation of the host response in normal individuals.

The effect of cold water immersion on the nasal mucosa.

The response of the nasal mucosa to cold water immersion is not well known. We have attempted to document this response in normal individuals. Seventeen individuals with no history of nasal disease or allergy were studied. All subjects were asked to perform sustained cold water (15 degrees C) immersion of their hand and forearm on the side of the obstructed nostril for a period of 5 min. The nasal cross-sectional area was measured on both sides of the nose using an acoustic rhinometer. The individuals were then rested for at least 30 min and the test repeated with immersion of the opposite hand. There was a significant fall in nasal cross-sectional area on the side of immersion (median change = 0.32 cm2, P = 0.0003) with a significant rise in nasal cross-sectional area on the none test side (median change = 0.35 cm2, P = 0.0003). There were no significant differences between these results and those obtained by immersion on the opposite side. The results indicate that cold water immersion produces nasal obstruction and that both afferent and efferent arms of this reflex are side-specific.

Effects of Sodium Bicarbonate Administration on the Exercise Tolerance of Normal Subjects Breathing Through Dead Space

The purpose of this study was to determine whether the administration of sodium bicarbonate to normal individuals would increase their PaCO2 and thereby decrease the ventilatory requirements at a given workload. In this double-blind crossover study, six normal men ingested either 3 mEq/kg NaHCO3 or 1 mEq/kg NaCl once a day for 5 days, in addition to 40 mg of furosemide and 40 mEq KCl. After each 5-day treatment, the subjects underwent a symptom-limited maximal bicycle ergometer exercise test while breathing through external dead space (with a volume of approximately 50% of their FEV1), a second exercise test without any external dead space, and an assessment of their respiratory response to hypercapnia. The administration of the NaHCO3 resulted in a significant increase in the arterial HCO3- from 20.8 to 24.0 mEq/L and a significant increase in the PaCO2 from 31.7 to 36.9 mm Hg at rest that persisted during exercise. During exercise periods with the added dead space, the Borg scores were significantly lower at each workload after the subjects received bicarbonate, but the maximal exercise level did not increase. The mean (+/-SD) slope of the mouth occlusion pressure response to hypercapnia was significantly lower after the administration of NaHCO3 than after NaCl, respectively: 0.73+/-0.41 vs 1.27+/-0.97 cm H2O/mm Hg. From this study we conclude that the administration of NaHCO3 results in a significant increase in the PaCO2, decreases the ventilation and the Borg score at equivalent workloads, and decreases the hypercapnic response in normal individuals.

B cells from patients with systemic lupus erythematosus display abnormal antigen receptor-mediated early signal transduction events.

To understand the molecular mechanisms that are responsible for the B cell overactivity that is observed in patients with SLE, we have conducted experiments in which the surface immunoglobulin (sIg)-mediated early cell signaling events were studied. The anti-sIgM-mediated free intracytoplasmic calcium ([Ca2+]i) responses were significantly higher in SLE B cells compared with responses of normal individuals and to those of patients with other systemic autoimmune rheumatic diseases. The anti-IgD mAb induced [Ca2+]i responses were also higher in lupus B cells than in controls. The magnitude of anti-sIgM-mediated Ca2+ release from intracellular stores was also increased in B cells from SLE patients compared with normal controls. The amount of inositol phosphate metabolites produced upon crosslinking of sIgM was slightly higher in patients with lupus than in normal controls, although the difference was not statistically significant. In contrast, the degree of anti-sIgM-induced protein tyrosine phosphorylation was obviously increased in lupus patients. Our study demonstrates clearly for the first time that SLE B cells exhibit aberrant early signal transduction events, including augmented calcium responses after crosslinking of the B cell receptor and increased antigen-receptor-mediated phosphorylation of protein tyrosine residues. Because the above abnormalities did not correlate with disease activity or treatment status, we propose that they may have pathogenic significance.

The nasal response to axillary pressure.

The changes in ipsilateral sympathetic tone in response to axillary pressure are well known. However, the response of the nasal mucosa is less well documented. We have attempted to demonstrate this response in normal individuals. Ten individuals with no history of nasal disease or allergy were studied. All subjects were exposed to sustained pressure, using a crutch, for a period of 5 min. Nasal cross-sectional area was measured on both sides of the nose using an acoustic rhinometer along with pulse and blood pressure. The individuals were then rested for at least 30 min and the test repeated with pressure applied to the opposite side. Statistical analysis was performed by non-parametric methods. There was a significant fall in nasal cross-sectional area on the side of pressure (median change = 0.09 cm2, P < 0.01) while cross-sectional area in the contralateral nasal passage increased (median change = 0.35 cm2, P = 0.01). There were no significant differences between these results and those obtained by axillary pressure on the opposite side. Pulse and diastolic blood pressure rose with axillary pressure while systolic blood pressure remained unaltered. There was no difference in the laterality in the blood pressure response. The results indicate that axillary pressure produces nasal congestion and both afferent and efferent arms of this reflex are side-specific.

Squatting revisited: comparison of haemodynamic responses in normal individuals and heart transplantation recipients.

Squatting produces a prompt increase in cardiac output and arterial blood pressure which is accompanied by an immediate decrease in heart rate and forearm vascular resistance. The rise in cardiac output and blood pressure has been attributed to augmented venous return from compression of leg veins, while the decreases in heart rate and forearm vascular resistance are probably due to activation of cardiopulmonary and arterial baroreflexes. Haemodynamic patterns in nine normal men and six heart transplant recipients during 2 min of squatting were examined to determine the role of cardiac innervation in the mediation of these responses. Stroke volume was monitored by ensemble averaged thoracic impedance cardiography and blood pressure was determined with an Ohmeda fingertip plethysmograph. These techniques provided continuous measurements which were capable of detecting transient and non-steady state changes. Forearm blood flow was measured with venous occlusion plethysmography. Measurements were obtained after 3 min of quiet standing, immediately after squatting, and at 20, 60, and 120 s of sustained squatting. Both groups exhibited similar increases in stroke volume index (normal individuals 10.5 ml/m2; heart transplant recipients 10.3 ml/m2) and mean arterial pressure (normal individuals 8.5 mm Hg; heart transplant recipients 5.0 mm Hg) which were sustained throughout squatting. Each group also showed an initial decrease in peripheral resistance (normal individuals 3.6 units; heart transplant recipients 7.7 units) followed by a return to baseline values after 20 s. Heart rate decreased in normal individuals (10 beats/min) but was unchanged or minimally increased (2 beats/min) in heart transplant recipients. Forearm vascular resistance was conspicuously decreased in normal individuals (47.8 units) but only minimally (20.9 units) and not significantly in heart transplant recipients. The major haemodynamic responses to squatting (increased cardiac output and blood pressure) are similar in normal individuals and heart transplant recipients. These responses are primarily due to augmented venous return and are not altered by cardiac denervation. Both groups also exhibited a transient decline in peripheral vascular resistance which is most likely mediated by arterial baroreflexes activated by the acute rise in arterial blood pressure. The absence of a significant decrease in forearm vascular resistance in heart transplant recipients suggests that this response is partially mediated by cardiopulmonary or ventricular baroreflexes or that local forearm flow mediated vasodilatation remains impaired after heart transplantation.

T Cell‐Mediated Cytotoxicity Against p53‐Protein Derived Peptides in Bulk and Limiting Dilution Cultures of Healthy Donors

The p53 tumour suppressor gene product plays an important role in the development of most human cancers. Point mutations in the p53 gene are common in malignant states and results in over-expression of wild type and mutant determinants of the p53 protein. This process might generate MHC-I restricted epitopes for T cell recognition and p53-derived peptides have been suggested as targets for tumour-specific cytotoxic T lymphocytes (CTL). Our primary aim was to estimate the frequencies of p53-peptide reactive CTL precursors (CTLp) in peripheral blood from healthy young individuals. We selected wild type and mutated peptides derived from the p53 sequence with a binding motif for HLA-A2.1 molecules. Peripheral blood mononuclear cells (PBMC) from healthy HLA-A2 donors were stimulated in vitro in bulk cultures as well as in limiting dilution cultures using autologous cells pulsed with p53 peptides as stimulator cells. T cell reactivity was observed towards both wild type and mutated p53 peptide epitopes with CTL precursor frequencies varying from 1:2 x 10(4) to 1:1.5 x 10(5). These results might suggest the presence of an ongoing immune response in normal individuals against cells expressing increased levels of p53 protein.

Depressed immune surveillance against cancer: role of deficient T cell: extracellular matrix interactions.

Although T cells infiltrate malignant tumors, the local immune response is usually inefficient and tumors escape destruction. While extracellular matrix proteins strongly costimulate T cell responses in normal individuals, our studies indicate that peripheral blood T cells from cancer patients and tumor infiltrating cells respond poorly or are resistant to stimulative signals mediated by collagen I and IV and fibronectin. Moreover, the adhesive properties of cancer T cells are markedly depressed. Those functional deficiencies are paralleled by variable deficits in integrin and non-integrin T cell receptors for extracellular matrix. Immunotherapy with BCG causes a dramatic but transient increase in T cell: ECM interactions.

Noninvasive assessment of CO2-induced cerebral vasomotor response in normal individuals and patients with internal carotid artery occlusions.

To evaluate the CO2-induced vasomotor reactivity of the cerebral vasculature, relative changes of blood flow velocity within the middle cerebral artery were measured by transcranial Doppler ultrasonography during normocapnia and various degrees of hypercapnia and hypocapnia. We studied 40 normal individuals and 40 patients with unilateral and 15 patients with bilateral internal carotid artery occlusions. When blood flow velocity changes as percent of normocapnic values were plotted against end-tidal CO2 volume percent, a biasymptotic curve (a tangent-hyperbolic function) gave the best fit of the scattergram. The distance between the upper and lower asymptotes was defined as cerebral vasomotor reactivity. In the normal individuals, mean +/- SD vasomotor reactivity was 85.63 +/- 15.96%. In patients with internal carotid artery occlusions, vasomotor reactivity was significantly lower than normal on both the occluded (mean 45.2%, median 50.4%; p less than 0.0001) and the nonoccluded (mean +/- SD 67.7 + 13.3%, p less than 0.01) sides in the unilateral group and on both sides (mean +/- SD 36.6 +/- 15.9% and 44.9 +/- 24.6%, p less than 0.0001) in the bilateral group. The difference between vasomotor reactivity for symptomatic and asymptomatic unilateral occlusions was also highly significant (mean 37.6% and 62.9%, p less than 0.006). Vasomotor reactivity was also significantly lower in patients with low-flow infarctions on computed tomography than in patients with normal scans (mean +/- SD 36.7 +/- 25% and 60.2 +/- 16.9%, p less than 0.008). A striking association of low-flow infarctions, ischemic ophthalmopathy, and hypostatic transient ischemic attacks was found with vasomotor reactivities of less than 34% or even paradoxical reactions.(ABSTRACT TRUNCATED AT 250 WORDS)