Evolving approaches of hematopoietic stem cell-based therapies to induce tolerance to organ transplants: the long road to tolerance.

The immunoregulatory properties of hematopoietic stem cells (HSCs) have been recognized for more than 60 years, beginning in 1945, when Owen reported that genetically disparate freemartin cattle sharing a common placenta were red blood cell chimeras. In 1953, Billingham, Brent, and Medawar demonstrated that murine neonatal chimeras prepared by infusion of donor-derived hematopoietic cells exhibited donor-specific tolerance to skin allografts. Various approaches using HSCs in organ transplantation have gradually brought closer to reality the dream of inducing donor-specific tolerance in organ transplant recipients. Several hurdles needed to be overcome, especially the risk of graft-versus-host disease (GVHD), the toxicity of ablative conditioning, and the need for close donor-recipient matching. For wide acceptance, HSC therapy must be safe and reproducible in mismatched donor-recipient combinations. Discoveries in other disciplines have often unexpectedly and synergistically contributed to progress in this area. This review presents a historic perspective of the quest for tolerance in organ transplantation, highlighting current clinical approaches.

Managed care in workers' compensation plans.

Workers' compensation plans have lagged behind most public and private health care plans in the adoption of managed care techniques. This is largely attributable to the underlying differences between workers' compensation and group health plans. Managed care techniques were developed within group health plans with the objective of health at the lowest cost. In workers' compensation, managed care must address a different objective-restoring a worker to health and productivity at the lowest cost. It is this fundamental difference that makes the application of managed care techniques to workers' compensation plans contentious and at times inappropriate. Research on the impact of managed care on the health and welfare of injured workers is sparse, and important questions remain about the appropriateness of care delivered under workers' compensation managed care plans. In this paper, we discuss the application of managed care to workers' compensation, and highlight the barriers to effective implementation.

Serum neopterin, beta2-microglobulin, soluble interleukin-2 receptors, and immunoglobulin levels in healthy adolescents.

Serum biomarkers, such as neopterin, beta2-microglobulin (B2M), and soluble interleukin-2 receptors (sIL-2R), are elevated in viral infections, including HIV-1 infection, and in inflammatory conditions, autoimmune disease, and malignancies. For many of these conditions, serum levels correlate with disease activity. Application of these biomarkers in adolescents is limited by a lack of information on the range and determinants of variability (age, sex, race) for serum levels of these important molecules in this age group. To address this question, we analyzed serum samples from a well-characterized heterogeneous population of 111 healthy adolescents. White children had significantly higher serum levels of sIL-2R and IgM and lower levels of IgG (P

Molecular markers of acute upper airway inflammation in workers exposed to fuel-oil ash.

Biomarkers in nasal lavage (NL) fluid may be useful in determining the presence and severity of upper airway inflammation. We studied 18 boilermakers overhauling a large, oil-fired boiler and 11 utility workers who served as controls for 6 wk. NL was performed before (NL1), during (NL2), and after (NL3) the overhaul. We measured nasal fluid levels of interleukins 6 (IL-6) and 8 (IL-8), eosinophilic cationic protein (ECP), and myeloperoxidase (MPO) as markers of response to fuel-oil ash exposure. In boilermakers, MPO was elevated during boiler work versus preboiler work (mean = 33.8 versus 22.7 ng/ml, p < 0.05), and at the 2-wk postexposure lavage (NL3) it had declined to 24.2 ng/ml (p = 0.08). Mean IL-8 levels increased in boilermakers between NL1 and NL2 (mean = 83.8 versus 134.8 pg/ml, p < 0.05), then decreased at NL3 (mean = 134.8 versus 89.0 pg/ml, p < 0.05). Nasal fluid vanadium increased in boilermakers between NL1 and NL2 (median < 1.0 versus 4.7 ppb, respectively, p < 0.05), then decreased at NL3 (median, 4.7 versus < 1.0 ppb, respectively, p < 0. 05). Levels of IL-6 and ECP did not change significantly during the study. Utility workers showed no significant change in any marker during the study period. Particulate matter < 10 micro(m) (PM10) levels were higher for boilermakers than for utility workers before boiler work (geometric mean (GM) = 0.40 versus 0.10 mg/m3, p < 0.05). This difference was more significant during boiler work (GM = 0.47 versus 0.13 mg/m3, p < 0.001). Ozone levels were low during the study. These data suggest that exposure to fuel-oil ash results in acute upper airway inflammation, potentially mediated by increased IL-8 levels and the recruitment and activation of polymorphonuclear leukocytes. These changes were associated with significantly increased PM10 levels and concentrations of upper airway vanadium.

Elevated serum interferon-gamma in atopic asthma correlates with increased airways responsiveness and circadian peak expiratory flow variation.

Interleukin (IL)-4, IL-5 and interferon (IFN)-gamma are thought to play an important role in chronic airway inflammation in asthmatic subjects. Increased airways responsiveness and nocturnal airway obstruction are important clinical manifestations of asthma. The aim of this study was to investigate whether IL-4, IL-5 and IFN-gamma values are elevated in atopic asthma and correlate with its clinical manifestations. Serum IL-4, IL-5 and IFN-gamma levels of 17 atopic asthmatics and eight nonatopic healthy subjects were determined at 16:00 and 04:00 h by a chemiluminescence enzyme-linked immunosorbent assay (ELISA) method. The clinical manifestation of asthma was determined by assessment of the degree of airway obstruction, airways responsiveness to methacholine and severity of nocturnal airway obstruction, defined as the mean circadian (16:00-04:00 h) peak expiratory flow (PEF) variation. Serum IL-4, IL-5 and IFN-gamma levels were significantly higher in asthmatic subjects as compared to healthy controls, both at 16:00 and 04:00 h. In asthmatic subjects serum IFN-gamma at both time points correlated significantly with the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20,meth) (rho= - 0.55) and with the mean 16:00-04:00 h PEF variation (rho = 0.53). In contrast, no relationship was found between the levels of IL-4 and IL-5 and the parameters of clinical manifestation of asthma. The results suggest that the serum interferon-gamma level is a reflection of the severity of airway inflammation in atopic asthma. More studies are needed to detect the cellular sources and to clarify the exact roles of interferon-gamma and other pro-inflammatory cytokines in asthma.

Blood interleukin-8 production is increased in chemical workers with bronchitic symptoms.

Chemical exposure may result in respiratory conditions such as chronic bronchitis, bronchial hyperresponsiveness, and chronic airway obstruction. Clinical studies have shown that during the course of disease, cytokine networks are changed. In order to study the relationship between blood cytokines and respiratory symptoms in an occupational setting, we investigated 106 chemical workers during a routine yearly medical examination in 1995. Lung function was measured with flow volume curves and impedance using the forced oscillation technique (FOT). Smoking-status and respiratory symptoms were determined by questionnaires. Cytokines were selected on biological plausibility and measured both in a whole blood assay (TNF-alpha, IL-8) and in serum (IL-4, IL-5, IL-6, IFN-gamma). The hypothesis is that blood levels of TNF-alpha and IL-8 are increased in bronchitis, while serum levels of IL4, IL-5 are increased and IFN-gamma is decreased in asthmatic workers. Spontaneous IL-8 release was significantly higher in workers with bronchitis (P < 0.05) or chronic bronchitis (P < 0.01) compared to workers without those respiratory symptoms, also after correction for age, pack-years, and blood lymphocyte numbers or compared to a matched control group. No correlation was present between specific cytokines and asthmatic symptoms. These data suggest that blood IL-8 may be considered as a useful marker for bronchitis.

Temporal variability in immunological parameters: peripheral blood mononuclear cell subsets, serum immunoglobulins, and soluble markers of immune system activation.

T-cell subsets and soluble factors of immune system activation are increasingly used as biologic markers of disease and predictors of disease progression. For example, changes in CD4 cells and CD4:CD8 ratio, sIL-2R, B2M, neopterin, and IgA have been used in predicting AIDS onset and progression. We examined the temporal variability of T-cell subsets, monocytes, natural killer cells, B cells, immunoglobulins, soluble interleukin-2 receptor (sIL-2R), neopterin, and beta-2 microglobulin (B2M) among 135 adults tested at two time points approximately 3 months apart. The purpose of the study was two-fold: (1) to assess the stability of these measures at two points in time, and (2) to investigate which parameters tend to track together over time, i.e., show significant longitudinal correlation. Mean population values for these immunologic parameters remained remarkably stable over the 3-month period. However, individual subjects exhibited significant temporal variability for many parameters. Unlike observations in patients with AIDS, changes in immunoglobulins and other soluble factors were not significantly correlated with changes in cellular subsets over the same period. However, change in B2M was correlated with change in neopterin (r = .35, p < or = .0001), and change in IgA was correlated with changes in IgG and IgM (r = .44, r = .54, P < or = .001 for both). Characterizing this temporal variability in a healthy population provides important information for researchers applying these tests in clinical and epidemiological studies.

Lymphocyte function and cytokine production during incremental exercise in active and sedentary males and females.

This study examined the effects of acute continuous incremental exercise on lymphocyte mitogenic function and cytokine production in physically active and sedentary males and females. Physically active (n = 32) and sedentary (N = 32) male and female subjects were randomly assigned to an exercise or control condition. Exercise involved a continuous incremental protocol consisting of cycling for 3 periods of 6 min at workrates corresponding to 55%, 70% and 85% VO2peak. Blood samples were drawn from a venous catheter at baseline, 6 min, 12 min and 18 min, and 2 h following completion of exercise. Relative to baseline and control condition the percentage of T (CD3+) and B cells (CD19+) significantly decreased, and the percentage of NK cells (CD3-CD16+CD56+) increased (p < 0.001) during each stage of the incremental exercise test. The proliferative response to ConA was suppressed, enhanced, or unchanged using 1.25 micrograms/ml, 2.5 micrograms/ml and 5.0 micrograms/ml ConA, respectively. The in-vitro production of IL-1 and IFN-gamma increased during each workload. In contrast IL-4 production did not change during exercise. The resting and exercise induced alterations in lymphocyte function and cytokine production were independent of gender and fitness level, and returned to baseline 2 h into recovery. The in-vitro production of IFN-gamma and IL-4 suggests that physical activity may alter the balance of TH1 and TH2 lymphocytes.

Endometrial Th2 cytokine expression throughout the menstrual cycle and early pregnancy.

Embryonic implantation and maintenance of pregnancy is influenced by the maternal immunological response. Type 2 T-helper (Th2) cells secrete interleukins 4, 5, 6 and 10 and are associated with suppression of cell-mediated immunity. Temporal changes in the expression of these cytokines were detectable by immunohistochemistry throughout the menstrual cycle. In pregnancy, 10-fold or greater increases in interleukin 6 and 10 secretion were detectable by enzyme-linked immunoassay compared with the non-pregnant state. The pattern of expression of Th2 cytokines suggests that progesterone may influence endometrial cytokine secretion. During pregnancy, Th2 expression paralleled that of vimentin, a stromal cell marker, suggesting that these cells may be a principal source of Th2 cytokines may be a mechanism of suppressing cell-mediated immunity in the endometrium, which may in turn enhance embryonic implantation and maintenance of pregnancy.

[Chemiluminescence assays for cytokines in serum: influence of age, smoking, and race in healthy subjects].

Evidence is accumulating that cytokines are important intermediates in the pathogenesis of many diseases such as asthma and pulmonary fibrosis. However, a major limitation to clinical studies of cytokines has been the inability to measure these important biomarkers in serum from normal, healthy controls. Without this capability, interpretation of apparently elevated levels in problematic, and evaluation of diseased level is impossible. We have recently developed chemiluminescence ELISA (CL-ELISA), resulting in a 100-fold increase in sensitivity. To assess the influence of age, smoking, and race on serum cytokine levels in healthy population, we measured IL-4, 5, 6, 10, IFN-gamma, and GM-CSF in serum of healthy Japanese (n = 38), and Americans (n = 10) using CL-ELISA. In this small population with narrow age range, no difference between smokers and nonsmokers was found for any cytokine. No correlations between age and cytokines was demonstrated. However, Japanese samples had lower levels of IL-4, 5, and 10 than American samples. Further evaluation using more controlled study design and larger populations will be necessary to determine whether this difference is due to inherent racial differences in Th2 cell function.

A murine model for assessing the respiratory hypersensitivity potential of chemical allergens.

Using equimolar quantities of 2 chemical allergens, toluene diisocyanate (TDI), noted for its ability to cause respiratory hypersensitivity, and dinitrochlorobenzene (DNCB), noted for its dermal sensitizing activity, the mouse was evaluated as a possible model to indicate respiratory hypersensitivity. A previously published procedure (Garssen et al. (1989) Immunology 68, 51-58) was followed whereby chemicals were applied epicutaneously to the shaved flank of BALB/c mice. Eight days later, animals were challenged by intranasal application of the chemical. The lungs were evaluated at 48 h. Both TDI and DNCB elicited mild mononuclear inflammatory cuffing around pulmonary vasculature. No reaction was noted around pulmonary airways. Sera, drawn 48 h following the intranasal challenge with chemical allergen, were evaluated for total IgE, hapten-specific IgE and IgG, and for IL-2, IL-4, IL-5, IL-6, and interferon gamma. Animals exposed to TDI demonstrated decreased total IgE and the presence of TDI-specific IgG. Cytokine levels were unchanged in both groups. These results indicate that in this mouse model, total serum IgE and the production of hapten-specific IgG antibodies distinguished a respiratory from a contact sensitizing chemical. Further comparison of the serologic response of mice to these two classes of chemicals is required to determine if the murine model can be used to predict dermal versus respiratory sensitizing activity of chemical allergens.

The association of ambient air pollution with twice daily peak expiratory flow rate measurements in children.

A stratified sample of 83 children living in Uniontown, Pennsylvania, reported twice daily peak expiratory flow rate (PEFR) measurements on 3,582 child-days during the summer of 1990. Upon arising and before retiring, each child recorded the time, three PEFR measurements, and the presence of cold, cough, or wheeze symptoms. Ambient air pollution, including particle-strong acidity, was measured separately during the day (8 a.m. to 8 p.m.) and at night. Each child's maximum PEFR for each session was expressed as the deviation from his or her mean PEFR over the study and adjusted to a standard of 300 liters/minute. The session-specific average deviation was then calculated across all of the children. A second-order autoregressive model for PEFR was developed, which included a separate intercept for evening measurements, trend, temperature, and 12-hour average air pollutant concentration weighted by the number of hours each child spent outdoors during the previous 12-hour period. The results are expressed in terms of the interquartile range for each pollutant. A 12-hour exposure to a 125-nmol/m3 increment in particle-strong acidity was associated with a -2.5 liters/minute deviation in the group mean PEFR (95% confidence interval (CI) -4.2 to -0.8) and with increased cough incidence (odds ratio (OR) = 1.6, 95% CI 1.1 to 2.4). A 30-ppb increment in ozone for 12 hours was associated with a similar deviation in PEFR levels (-2.8, 95% CI -67 to 1.1). The association between PEFR and particle-strong acidity was observed among the 60 children who were reported as symptomatic on the prior symptom questionnaire (-2.5, 95% CI -4.5 to -0.5). The authors conclude that summer occurrences of excessive acid aerosol and particulate pollution are associated with declines in peak expiratory flow rates in children.

Racial differences in serum immunoglobulin levels: relationship to cigarette smoking, T-cell subsets, and soluble interleukin-2 receptors.

To investigate the influence of race, cigarette smoking, and immunologic parameters on serum immunoglobulins, we analyzed serum IgG, IgA, and IgM levels in 455 healthy adults. The study population ranged in age from 20 to 69 years, including 282 whites and 173 blacks, 181 never-smokers, 93 ex-smokers, and 181 current smokers. Race and smoking were independently associated with alterations in serum IgG levels. Blacks had significantly higher IgG levels than whites (1,587 vs. 1,209 mg/dl; P < 0.001), and never smokers had significantly higher levels than current smokers (1,426 vs. 1,287 vs. mg/dl; P < 0.001). IgA and IgM levels were unrelated to race or smoking. Serum IgG was also found to be directly related to the proportion of HLA-DR+ cells and the level of soluble interleukin-2 receptors (sIL-2R) and inversely related to the proportion of CD4+ cells. Investigation of this racial heterogeneity may provide insights into the pathogenesis of immunologic diseases that exhibit unexplained racial variation.

Factors influencing serum neopterin and beta 2-microglobulin levels in a healthy diverse population.

Sera and questionnaire data from a population-based random sample of healthy adults was used to evaluate factors influencing neopterin and beta 2-microglobulin (beta 2m) values. Both neopterin and beta 2m levels increased with age and were higher among white than blacks (mean values for whites and blacks: neopterin, 5.06 vs 4.49 nmol/L; beta 2m, 1.36 vs 1.28 mg/L). Gender differences were noted for beta 2m but not neopterin values (beta 2m males vs females: 1.37 vs 1.29 mg/L). Neopterin values were lower among current smokers than among nonsmokers (4.32 vs 5.16 nmol/L) and were higher among users of antihistamines (5.46 among users vs 4.65 nmol/L among nonusers). Neopterin and beta 2m were correlated in this healthy adult population (adjusted r = 0.53, P = 0.001), yet no other interrelationships with numerous biologic markers except between beta 2m and serum-soluble interleukin-2 receptor levels (adjusted r = .41, P = 0.05) were observed. These findings provide important baseline information to consider before planning or evaluating studies utilizing neopterin or beta 2m levels.

Predictive value of airways hyperresponsiveness and circulating IgE for identifying types of responses to toluene diisocyanate inhalation challenge.

Development of asthma after exposure to toluene diisocyanate (TDI) has been recognized in a variety of occupational settings. However, the pathogenesis of isocyanate-induced asthma remains controversial. In particular, the role of IgE in the development of TDI-induced asthma has remained uncertain. To investigate predictive factors for response to inhalation challenge with TDI, we analyzed data from 63 subjects referred for evaluation of respiratory symptoms thought to be related to TDI sensitization. All subjects underwent interview, routine phlebotomy, spirometry, methacholine challenge, and allergy skin testing prior to TDI challenge. Spirometry and methacholine challenge were repeated 1 day after TDI challenge. The cumulative dose of methacholine needed to produce a 20% decrease in FEV1 (PD20) was determined. A PD20 of 1.4 mg or more was considered normal. Subjects were challenged by exposure to 5 to 10 ppb TDI for up to 30 min in a 9 m3 exposure chamber. A positive response was a 20% or more decrease in FEV1 within 1 h (early) or beyond 1 h (late) after TDI exposure. Thirty-four subjects (54%) had a positive response, of whom 12 (35% of responders) had isolated early responses, 13 (38%) had isolated late responses, and the remainder had dual responses. Thirty-two individuals (51%) had a positive response to methacholine (AR+) prior to TDI challenge. AR+ was strongly associated with a positive TDI challenge: 23 AR+ subjects (72%) had a positive TDI challenge, compared with only 11 AR- subjects (35%) (p < 0.01). AR positivity did not predict the time of onset of TDI response.(ABSTRACT TRUNCATED AT 250 WORDS)

Racial variation in serum-soluble interleukin-2 receptor levels: a population-based study of healthy smokers and nonsmokers.

To investigate the influence of race and cigarette smoking on serum levels of soluble interleukin-2 receptors (sIL-2R), we studied a population-based cohort of 282 white and 173 black adults, ages 20-69 years. Serum sIL-2R concentrations in this healthy population ranged from 146 to 2623 U/ml. Whites had significantly higher sIL-2R levels than blacks (455 versus 365 U/ml; P < 0.001), and cigarette smokers had significantly higher levels than nonsmokers (508 versus 420 U/ml; P = 0.01). White smokers had the highest levels (550 U/ml); white nonsmokers and black smokers had intermediate levels (455 and 450 U/ml, respectively); and black nonsmokers had the lowest levels (365 U/ml). Smoking cessation appeared to normalize sIL-2R levels; exsmokers who had not smoked for at least 2 years had sIL-2R levels similar to those of never smokers. These data demonstrate the wide range of serum sIL-2R concentrations found in normal healthy adults and the significant influence of race and cigarette smoking. Further investigation of this natural heterogeneity may provide insights into the mechanisms underlying genetic and environmental influences on this important immunologic parameter.

Thrombocytopenia in the intensive care unit.

STUDY OBJECTIVE: To determine the prevalence of thrombocytopenia in an ICU and assess which factors were associated with thrombocytopenia. DESIGN: A review of the medical records of patients admitted during 3 separate months during 1 academic year. Patients must have survived at least 12 h in the ICU. SETTING: A medical ICU at a university hospital. PATIENTS: General medicine patients admitted to the ICU. INTERVENTIONS: All medical records were reviewed. During the ICU stay, daily medications, events, and platelet count were noted. All patients were followed up until death or hospital discharge. In 22 patients, including 18 who had thrombocytopenia, bone marrow aspirates were performed. MEASUREMENTS AND RESULTS: One hundred sixty-two admissions were evaluated. Thirty-eight (23 percent) had platelet counts less than 100,000/mm3 at least once, and 17 (10 percent) patients had platelet counts less than 50,000/mm3. Several factors were associated with thrombocytopenia; however, only sepsis, use of antineoplastic chemotherapy, elevated creatinine level, or elevated bilirubin value were independent risk factors for severe thrombocytopenia. In only one patient were the bone marrow findings different from those expected by the clinical presentation. Thrombocytopenia was associated with longer hospital stay (p < 0.001) and higher mortality (p < 0.001). CONCLUSION: Thrombocytopenia is a common occurrence in the ICU, usually due to the underlying disease, and is associated with an increased mortality.

Airway responsiveness in young black and white women.

The prevalence and severity of asthma appears to be greater in blacks than in whites. To determine if racial differences in airway responsiveness may explain these findings, methacholine challenge tests from 62 black and 238 white women 20 to 35 yr of age were evaluated. Subjects served as controls for a case-control study of the relation of airway responsiveness and preterm labor. Standardized questionnaires were used to obtain information on age, obstetrical history, education, income, cigarette smoking, medication use, and respiratory illnesses and symptoms. Total serum IgE was measured using a radioimmunoassay. Methacholine challenge testing was performed on all subjects 6 wk after delivery, and the provocative dose causing a 20% decrease in FEV1 (PD20) was calculated. Black women in the study had more pregnancies and children, were younger, less well educated and more impoverished, and reported greater cigarette smoking and less medication use than did the white women. Additionally, black women had higher geometric mean serum IgE levels (blacks: 65.4 IU versus whites: 20.0 IU; p < 0.001), lower FEV1 (blacks: 2.73 +/- 0.38 SD L versus whites: 3.19 +/- 0.39 L; p < 0.001), and greater unadjusted airway responsiveness than did white women (geometric mean PD20: blacks: 28.4 mumol versus whites: 38.8 mumol; p = 0.02). After adjusting for selective demographic and smoking differences, a significant additional effect of race on mean PD20 was found. However, after adjustment for level of serum IgE and level of FEV1, racial differences were no longer apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated soluble interleukin-2 receptors in young healthy cigarette smokers: lack of association with atopy or airways hyperresponsiveness.

To study the relationship of atopy and nonspecific airways hyperresponsiveness to circulating levels of soluble interleukin-2 receptors (sIL-2R), we measured serum sIL-2R concentrations in 40 young, healthy smokers and non-smokers. Levels of sIL-2R were significantly higher in current smokers than in nonsmokers (median sIL-2R levels 605 vs. 398 U/ml, respectively; p less than 0.05). Serum sIL-2R levels were not related to nonspecific airways hyperresponsiveness to methacholine, allergy skin test reactivity, doctor-diagnosed asthma or hay fever, or respiratory symptoms of wheeze. Among current smokers, a trend toward higher sIL-2R levels (not statistically significant) was observed among subjects reporting symptoms of phlegm production. The increase in sIL-2R levels associated with cigarette smoking was similar in magnitude to that reported for immune-mediated conditions such as collagen vascular diseases and eczema. These data confirm that cigarette smoking is an important determinant of sIL-2R level, even among young healthy subjects. This effect does not appear to be related to atopic status or bronchial responsiveness. Among cigarette smokers, sIL-2R level may be related to the presence of conditions associated with phlegm production.