Femur length and trisomy 21: impact of gestational age on screening efficiency

OBJECTIVE

This study assesses two methods used to define relatively short femur in screening for trisomy 21 and examines changes in performance of screening with gestational age.

DESIGN

Retrospective analysis of data on menstrual age, femur length (FL) and biparietal diameter (BPD) in 49 trisomy 21 pregnancies and 6069 normal controls. Reference ranges were derived for BPD/FL versus menstrual age and for FL versus BPD. Two methods of defining short femur (BPD/FL and observed-to-expected FL ratio) were examined for false-positive rates and detection rates for trisomy 21 at different gestational ages.

RESULTS

In the control group the BPD/FL ratio and its standard deviation decreased with menstrual age. Trisomy 21 was associated with a significantly higher BPD/FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). Eleven percent of 28 fetuses examined at 15-17 weeks had a BPD/FL above the 95th centile compared with 24% of 21 fetuses examined at 18-20 weeks (P = 0.40). The median observed-to-expected FL ratio in the control group was 1.0 throughout the gestational age range but the standard deviation decreased significantly with menstrual age (P < 0.01). Trisomy 21 was associated with a significantly reduced observed-to-expected FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). A fixed cut-off of 0.91 for observed-to-expected FL ratio provided a false-positive rate of 12% at 15-17 weeks compared with 6% at 18-20 weeks of gestation (P < 0.001) with detection rates of 29 and 38%, respectively (P = 0.73).

CONCLUSION

Irrespective of the definition used to define the condition, relatively short femur is a poor marker for trisomy 21 particularly when the assessment takes place before 18 weeks of gestation.

Extreme oxygen sensitivity of electronic properties of carbon nanotubes

The electronic properties of single-walled carbon nanotubes are shown here to be extremely sensitive to the chemical environment. Exposure to air or oxygen dramatically influences the nanotubes' electrical resistance, thermoelectric power, and local density of states, as determined by transport measurements and scanning tunneling spectroscopy. These electronic parameters can be reversibly "tuned" by surprisingly small concentrations of adsorbed gases, and an apparently semiconducting nanotube can be converted into an apparent metal through such exposure. These results, although demonstrating that nanotubes could find use as sensitive chemical gas sensors, likewise indicate that many supposedly intrinsic properties measured on as-prepared nanotubes may be severely compromised by extrinsic air exposure effects.

The management and production of risk in romantic relationships: a postmodern paradox

Expanding on the work of Ulrich Beck and other social theorists, the central thesis of this article is that individuals in contemporary North American society are increasingly motivated by the need to alleviate expanding levels of perceived risks associated with interpersonal love relationships and mate selection. In response to these perceived risks, men and women today are altering their relationship patterns in such a way that the process of relationship formation and assessment has become increasingly rationalized. As a result, a paradox has been created between the rational management of interpersonal risk associated with romance and the production of risk. This article is primarily a theoretical treatment of the issues, augmented with data on the social history of adolescence, courtship, and marriage and a review of the literature on mate selection processes in contemporary society.

Effect of erythromycin on myocardial repolarization in patients with community-acquired pneumonia

BACKGROUND

Erythromycin has been associated with prolongation of myocardial repolarization and torsades de pointes (TdP).

METHODS

To determine the frequency, dose-response, and risk factors for erythromycin-associated prolongation of myocardial repolarization, we observed data of patients admitted to our hospital with pneumonia who were treated with erythromycin.

RESULTS

In 35 women and 28 men enrolled in this study, the QTc increased from 434 +/- 4 milliseconds at baseline to 464 +/- 5 milliseconds after receiving a cumulative dose of 3.2 +/- 0.2 g of erythromycin. Neither age, sex, presence of preexistent congestive heart failure/coronary artery disease, electrolyte values, nor cumulative dose of erythromycin was associated with QTc prolongation. In 27 patients who received intravenous erythromycin for 3 days, the QTc increased from 427 +/- 5 milliseconds before to 461 +/- 8 milliseconds at 24 hours but did not increase further by day 3 (457 +/- 10 milliseconds). No patient in this cohort had TdP.

CONCLUSIONS

Erythromycin therapy is associated with prolongation of myocardial repolarization that manifests after the first few doses in a majority of patients.

Local treatment with IL-12 is an effective inhibitor of airway hyperresponsiveness and lung eosinophilia after airway challenge in sensitized mice

BACKGROUND

Systemic administration of IL-12 can prevent airway hyperresponsiveness (AHR) in mice after sensitization and repeated allergen challenge. However, systemic IL-12 has been associated with severe adverse effects.

OBJECTIVE

We determined whether IL-12 administration to the airways in a dose sufficiently low so as not to result in systemic effects can modify allergic inflammation and AHR after allergen challenge.

METHODS

Mice were sensitized to ovalbumin by intraperitoneal injection and challenged with ovalbumin aerosol on 3 consecutive days. During the period of challenge, IL-12 was administered intranasally following 2 regimens, designated high (1500 ng) or low (150 ng). We monitored airway responsiveness to inhaled methacholine by barometric body plethysmography, lung inflammatory cells, local cytokine production, and, to assess systemic effects of IL-12 treatment, spleen weights and numbers of eosinophils in the bone marrow.

RESULTS

Allergen challenge resulted in increases in airway responsiveness and in numbers of lung eosinophils. These increases were prevented by both high- and low-dose IL-12. Additionally, IL-12 administration resulted in enhanced local interferon-gamma production and prevented the increases in local IL-4 and IL-5 production after airway challenge. A high dose, but not a low dose, of IL-12 resulted in increased spleen weights and prevented the increase in numbers of bone marrow eosinophils after allergen challenge.

CONCLUSION

These data indicate that local administration of IL-12 can prevent AHR and reduce lung eosinophilia after allergen challenge in sensitized mice without eliciting systemic adverse effects. IL-12 exerts these effects by inducing local T(H1)-type responses in the airways in a setting that is normally dominated by T(H2)-type responses.

New-onset bronchospasm or recrudescence of asthma associated with cocaine abuse

OBJECTIVE

To determine whether the occurrence of new-onset bronchospasm or the recrudescence of asthma is associated with the use of cocaine.

METHODS

A consecutive sample of patients presenting to an inner-city adult ED with new-onset bronchospasm or recrudescence of bronchospasm after > 5 years were prospectively enrolled in a case-control prevalence study. The bronchospasm patients were queried as to their exposure to illicit drugs, and urine was obtained to screen for cocaine and its metabolite, benzoylecgonine. An age- and sex-matched control group was composed of randomly chosen subjects without respiratory complaints or a history of asthma. The control group was also screened by urine toxicology for cocaine and its metabolite, benzoylecgonine.

RESULTS

In the asthma group, 21/59 (36%) had a urine toxicologic screen positive for cocaine metabolite (benzoylecgonine). Of the 21 with a positive screen for cocaine, 8 denied illicit drug abuse. Among the 13 patients reporting drug use, 10 said that they smoked crack and 3 snorted cocaine. In the control group, 8/53 (15%) were positive. Multivariate logistic regression analysis, with adjustment for age and sex, indicated that the use of cocaine was associated with a 3-fold higher prevalence of new-onset bronchospasm or recrudescence of asthma (OR = 3.28, 95% CI: 1.26 to 8.50).

CONCLUSIONS

There appears to be an association between cocaine use and new-onset bronchospasm or recrudescence of asthma in this inner-city ED population. Further study is necessary to determine the basis for this association.

Allergen-specific IgE and IL-5 are essential for the development of airway hyperresponsiveness

The mechanisms underlying the development of airway hyperresponsiveness are not fully delineated. We addressed this question by studying the effects of passive sensitization with anti-OVA IgE on the development of altered airway responsiveness (AR) following local challenge with OVA in normal and athymic mice. Both normal and athymic BALB/c mice developed allergen-specific immediate cutaneous hypersensitivity after passive sensitization with anti-OVA IgE. In contrast, the combination of local challenge with allergen via the airways and passive sensitization triggered the development of airway hyperresponsiveness only in normal but not in athymic mice. Treatment of athymic mice with IL-5 significantly increased eosinophil accumulation in the lungs after local challenge with OVA; increased airway reactivity was only observed in athymic mice which received anti-OVA IgE, not an unrelated IgE, plus IL-5 treatment and airway challenge with OVA. These findings identify the requirement for allergen-specific IgE and IL-5 for the development of airway hyperresponsiveness following allergen challenge via the airways.

Increased fetal colonic muscle contractility following glucocorticoid and thyroxine therapy: implications for meconium passage

The incidence of meconium-stained amniotic fluid increases with advanced gestational age and fetal stress, and meconium passage is likely dependent on fetal colonic muscle function. Antenatal hormone exposure improves fetal pulmonary and cardiovascular function. We hypothesized that in utero exposure to steroid or thyroid hormones effect an increase in fetal distal colonic muscle contractility. In a randomized controlled study 126-day (term 145 days) ovine fetuses were treated with a single ultrasound-guided intramuscular injection of 0.5 mg/kg betamethasone (n = 5), betamethasone plus 60 micrograms/kg thyroxine (n = 5), or saline (n = 7). After 48 h, fetuses (128 days) were delivered, distal colon segments were removed, and peak tension responses to bethanechol (10(-8) to 10(-3) M) characterized in vitro. Peak muscle tensions were significantly greater in fetuses exposed to combined betamethasone and thyroxine therapy (989 +/- 190 g/cm2) than in saline-treated animals (509 +/- 91 g/cm2). There was difference in the maximum tension response between betamethasone alone (559 +/- 75 g/cm2) and the saline animals. The bethanechol ED50 values (2.1 +/- 0.5 x 10(-5) M) were not different among the three groups. Antenatal fetal betamethasone and thyroid hormone treatment increases fetal colonic muscle contractility. We speculate that endogenous or exogenous fetal maturational agents may facilitate the passage of meconium.

Posttranscriptional regulation of T-cell IL-2 production by human pooled immunoglobin

We evaluated the mechanism by which human pooled gamma-globulin for intravenous use (hIVIG) inhibits interleukin-2 (IL-2) production by human T cells. hIVIG reduced by 70-95% the amount of IL-2 in culture supernatants from mitogen-stimulated peripheral blood T cells or Jurkat cells. This reduction was not apparent at the transcriptional level: hIVIG had no effect on the levels of IL-2 mRNA or on the accumulation of firefly luciferase when its gene was linked to the IL-2 promoters. In contrast, hIVIG inhibited IL-2 protein synthesis, and the intracellular IL-2 was not restored by monensin. Our results indicate that the inhibition of IL-2 production by hIVIG occurred post-transcriptionally, and also suggest that secretion was unaffected, and that this effect of hIVIG was specific for IL-2 (and possibly other related cytokines). The data identify a previously uncharacterized regulatory mechanism of IL-2 production and predict that this immunomodulatory effect of hIVIG may be significant for its therapeutic actions in immune-mediated diseases.

Efficacy of atropine sulfate in combination with albuterol in the treatment for acute asthma

OBJECTIVE

To determine the efficacy of combination therapy using atropine sulfate and albuterol in the treatment for an acute exacerbation of asthma.

METHODS

A prospective, randomized double-blind, placebo-controlled study was performed in the ED of a large, inner-city, university-affiliated teaching hospital. Participants were a convenience sample of patients presenting to the ED between September 1993 and March 1994 with acute exacerbations of their asthma. Patients judged to be in extremis were excluded. All patients received 3 nebulized treatments with 2.5 mg of albuterol at 0, 30, and 60 minutes. Patients were randomized into 1 of 3 groups with the following added to their nebulizer solutions: 1) saline placebo during all 3 treatments; 2) 2.0 mg atropine sulfate added to the first nebulizer and saline in the second and third; or 3) 2.0 mg atropine to the first and third treatments (with saline in the second). No other medication was administered during the study period. At 90 minutes, the patients were evaluated for admission or release from the ED according to predetermined criteria, and additional medications were given as necessary. Vital signs, peak expiratory flow rate (PEFR), degree of wheezing, level of distress, and side effects were measured before and after each nebulizer treatment.

RESULTS

Of the 153 patients eligible for the study, 126 completed the entire study protocol. There was no significant difference between the 3 groups on any parameter studied, including improvement of PEFR, vital signs, or level of distress. There was no difference in the admission rate between the 3 groups, nor was there a difference in the incidence of side effects among the groups.

CONCLUSION

In this study population, combination therapy with atropine sulfate and albuterol offered no significant benefit over the use of albuterol alone in the treatment for acute exacerbation of asthma.

College research associates: a program to increase emergency medicine clinical research productivity

STUDY OBJECTIVE

To evaluate a program using health care preprofessional college students as research associates (RAs) to facilitate research in emergency medicine.

METHODS

We developed a program using health care preprofessional college students as RAs in an urban ED with an emergency medicine residency program. RAs were recruited from four local colleges. Potential RAs were instructed during four 2-hour sessions on clinical research in emergency medicine, the ethical issues of confidentiality and informed consent, personal safety, and specifics on data collection for the individual studies. For the 13 weeks of the 1995 spring semester, each RA served one 4-hour shift in the ED each week. They identified patients who were eligible for the studies, began the informed-consent process, obtained nonclinical and historical information, and assisted the physicians in the study protocols. The RAs were evaluated on every shift by two faculty members from New York Medical College. The RAs were surveyed at the completion of the semester about their experiences with the program.

RESULTS

Forty-one students completed the orientation course and served at least one shift in the ED. Thirty-three completed more than 7 of 13 possible shifts and received credit for the semester. The average number of shifts served for all RAs was 9 (average numbers of shifts served by RAs receiving credit for the semester and RAs not receiving credit were 10.3 and 4, respectively). Two studies were completed during the semester, each with a significant increase in patient enrollment after the RAs' arrival. Three studies were ongoing at the end of the semester and had patient entries well above projected expectations. The principal investigators for the studies expressed their satisfaction with the RAs' productivity. The faculty evaluations were overwhelmingly positive, as were the results of the RA survey at the end of the semester. The cost of the program was minimal.

CONCLUSION

College students serving as research associates can be an economical and successful tool for clinical studies in the emergency department.

Synthesis of classical pathway complement components by chondrocytes

Using immunohistochemical studies, C1q, C1s, C4 and C2 were detected in chondrocytes in normal human articular cartilage and macroscopically normal articular cartilage from the inferior surfaces of hip joints of patients with osteoarthritis. Using reverse-transcribed polymerase chain reaction (RT-PCR), mRNA for C1q, C1s, C4 and C2 was also detected in RNA extracted from articular cartilage. C1r, C3, C1-inhibitor, C4-binding protein and factor I were not detected by either technique. Articular chondrocytes cultured in vitro synthesized C1r, C1s, C4, C2, C3 and C1-inhibitor but not C1q, C4-binding protein or factor I, as assessed by enzyme-linked immunosorbent assay (ELISA) and Northern blot analysis. Thus cultured articular chondrocytes have a complement profile that is similar to that of cultured human fibroblasts rather than that of articular chondrocytes in vivo. Complement synthesis in cultured chondrocytes was modulated by the cytokines interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), showing that cytokines can probably regulate complement synthesis in intact cartilage. The possible roles of local synthesis of complement components by chondrocytes in matrix turnover and the regulation chondrocyte function are discussed.

Requirement for CD8+ T cells in the development of airway hyperresponsiveness in a marine model of airway sensitization

To study the role of CD8+ T cells in allergic sensitization, we examined the effects of in vivo depletion of CD8+ T cells prior to sensitization on IgE production, immediate type cutaneous hypersensitivity and development of altered airway responsiveness. BALB/c mice were thymectomized and treated with anti-CD8 antibody resulting in depletion of CD8+ T cells (<1%) in spleen and lymphoid tissues. In these mice, sensitization to ovalbumin (OVA) via the airways still resulted in IgE anti-OVA responses and immediate cutaneous reactions to OVA, but the animals were unable to develop airway hyperresponsiveness, eosinophil infiltration of the lung parenchyma, or IL-5 production in the local lymph nodes of the airway. Transfer of CD8+ T cells from naive animals during sensitization (on day 8 of the 10-d protocol) fully restored the ability to develop airway hyperresponsiveness and this was accompanied by IL-5 production and eosinophil accumulation in the lung. These data indicate a critical role for CD8+ T cells in the production of IL-5 and the development of altered airway responsiveness after antigen sensitization through the airways.

Prevention of the development of immediate hypersensitivity and airway hyperresponsiveness following in vivo treatment with soluble IL-4 receptor

The effects of local versus systemic treatment with soluble IL-4 receptors (sIL-4R) were tested in a model of allergen-induced immediate hypersensitivity responses in BALB/c mice. Mice sensitized through the airways to ovalbumin (OVA) by ultrasonic nebulization once a week for 4 weeks developed increased serum anti-OVA IgE and IgG1 antibody titers and these were accompanied by immediate-type skin test responses to the allergen. These responses were also associated with the development of increased airway responsiveness (AR) as monitored by electrical field stimulation of tracheal smooth muscle preparations in vitro. Sensitized mice, treated by intraperitoneal injections of sIL-4R (150 micrograms/injection) administered in parallel to the sensitization protocol, developed significant suppression of anti-OVA IgE, anti-OVA IgG1 antibody production and of immediate cutaneous hypersensitivity responses. Airway responsiveness was normalized to some extent. Total IgE production was only slightly reduced. These effects were comparable to the findings following intraperitoneal injection of monoclonal anti-IL-4 antibody. Administration of sIL-4R via the airways was also effective in inhibiting the development of immediate hypersensitivity responses, including IgE production, and was more potent in normalizing airway responsiveness. These effects were achieved at lower concentrations than needed for systemic treatment. These data suggest that delivery of sIL-4R via the airways can effectively modulate the development of immediate hypersensitivity and airway hyperresponsiveness in response to aerosolized allergen.

Nerve growth-factor and anti-CD40 provide opposite signals for the production of IgE in interleukin-4-treated lymphocytes

Nerve growth factor (NGF) is a well-known neurotrophic factor acting on both the peripheral and the central nervous systems. In addition, it has been shown to play a role in the function of the immune system through specific receptors. Both high-affinity and low-affinity NGF receptors (NGFR) are expressed on human B lymphocytes. The low-affinity NGFR has been shown to have structural homology with another specific B cell surface molecule, CD40, which plays an important role in IgE production. In view of the structural similarities of the p75 NGFR and CD40 we examined whether NGF may also be involved in the regulation of IgE production. We found that NGF and anti-CD40 exerted opposite effects on the induction of IgE by IL-4 in peripheral blood mononuclear cells. NGF inhibited the induction of IgE by IL-4 and this inhibition was not mediated through blocking of the induction of CD23 nor through inhibition of IL-4R expression. The inhibition of IL-4-dependent IgE production was observed on surface (s)IgE+ and sIgE-/sIgM+ B lymphocytes. Anti-CD40 on the other hand, exerted an enhancing effect on IgE production and its addition to IL-4 provided a signal that was resistant to the inhibitory effect of NGF. Antagonistic effects of NGF and IL-4 were also observed for other Ig isotypes since IL-4 prevented the increase in IgA and IgM production induced by NGF. These data indicate that although NGFR and CD40 belong to the same receptor superfamily and exert similar proliferative effects on B lymphocytes, they interact differently with IL-4 in the regulation of IgE production.

Production of interleukin-4 and interferon-gamma by TCR-V beta-expressing T-cell subsets in allergen-sensitized mice

Sensitization of BALB/c mice to ovalbumin (OVA) through the airways stimulated allergen-specific immediate hypersensitivity responses and these effects were related to the expansion of V beta 8.1/8.2+ T cells. In contrast, splenic V beta 2+ T cells from sensitized animals inhibited V beta 8.1/8.2+ T-cell induction of anti-OVA IgE production in vivo. To examine whether such differences in T-cell function were associated with differences in cytokine production, CD4+ T cells and CD4+ T cells depleted of V beta 8.1/8.2+ T cells were analyzed for interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) production. In nonsensitized animals, no differences in IL-4 and IFN-gamma production were found in mRNA levels as well as in protein levels in these two populations of cells. In contrast, CD4+ T cells from sensitized mice showed higher IL-4 and lower IFN-gamma production than CD4+ cells depleted of V beta 8+ lymphocytes. Similar results were obtained after stimulation of CD4+ T cells from OVA-sensitized animals with anti-V beta 2 and anti-V beta 8.1/8.2 antibodies. Stimulation of V beta 8.1/8.2+ T cells from sensitized mice with OVA or OVA peptide 323-339 also resulted in increased production of IL-4. These data indicate that allergen sensitization via the airways stimulates the selective expansion of certain V beta-expressing T cells and that these T-cell subsets exhibit different functional activities in terms of cytokine production.

DDAVP-induced maternal hyposmolality increases ovine fetal urine flow

Fetal urine flow is influenced by fetal intravascular volume, glomerular filtration rate, tubular reabsorption, and fluid regulatory hormones. As maternal-to-fetal fluid transfer is dependent on hydrostatic and osmotic gradients, we postulated that a chronic decrease in maternal plasma osmolality would promote transplacental fluid transfer and increase fetal urine flow. Six pregnant ewes and singleton fetuses (131 +/- 2 days; term = 150 days) received bladder and hindlimb arterial and venous catheters. After 5 days, plasma and urine composition, urine flow rate (Uvol), and plasma arginine vasopressin (AVP) levels were measured during a 2-h control period. At 2 h, tap water (2 liter, 38 degrees C) was administered to the ewe. At 3 h, ewes received a 20-micrograms bolus of 1-desamino-[D-Arg8]vasopressin (DDAVP), followed by continuous infusion (4 micrograms/h). In response to water loading, maternal urine osmolality decreased (761 +/- 158 to 339 +/- 13 mosmol/kgH2O), and Uvol increased. After DDAVP, maternal urine osmolality increased (1,270 +/- 89 mosmol/kgH2O), and Uvol, hematocrit, plasma osmolality (304 +/- 1 to 284 +/- 4 mosmol/kgH2O), and protein concentration decreased. Five hours after maternal DDAVP infusion, fetal plasma osmolality decreased (300 +/- 1 to 281 +/- 3 mosmol/kgH2O), and Uvol increased (0.4 +/- 0.1 to 1.3 +/- 0.2 ml/min) and remained elevated at 24 h. There was no change in fetal plasma DDAVP (immunoreactive AVP) levels or fetal urine osmolality. Controlled changes in maternal plasma osmolality may prove useful in modulating fetal urine flow and, ultimately, amniotic fluid volume.

Inhibition of the development of immediate hypersensitivity by staphylococcal enterotoxin B

We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive V beta 8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of V beta 8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization of OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the V beta 8 T cell population, they did reduce the proliferative response of V beta 8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive V beta 8 T cells.

Suppression of cytokine-dependent human T-cell proliferation by intravenous immunoglobulin

Human intravenous immunoglobulin (hIVIG) modifies the course of numerous immune-mediated diseases, but its specific mode of action remains unknown. In order to delineate possible immunoregulatory mechanisms, we studied the effects of hIVIG on the in vitro proliferation of human T cells. Cells from normal donors were stimulated with anti-CD3 antibody, tetanus toxoid antigen or the combination of a phorbol ester/ionomycin (P/I) and incubated with increasing concentrations of hIVIG (1 mg/ml to 10 mg/ml) for three to seven days. Addition of hIVIG inhibited anti-CD3 and tetanus but not P/I-induced proliferation in a dose-dependent manner. Addition of exogenous IL-2 to the cultures overcame the inhibitory effect of hIVIG; addition of IL-4 was ineffective. To further define the effect of hIVIG on specific cell populations, competent, purified T cells were stimulated with anti-CD3 or phorbol ester for three days in the presence of hIVIG. Addition of hIVIG blocked anti-CD3 and phorbol ester-induced stimulation of competent T cells. In cultures of competent T cells, either IL-2 or IL-4 was successful in reversing the hIVIG-induced inhibition. In these cultures, hIVIG also significantly prevented the synthesis/secretion of both IL-2 and IL-4 in PDB-stimulated competent T cells. Taken together, these data suggest that one mechanism of action of hIVIG may be through its interference with cytokine-dependent T-cell proliferation.

Enhancement of IgE production by anti-CD40 antibody in atopic dermatitis

It has been recently recognized that the obligate requirement for T cells in the development of IgE responses can be substituted for by anti-CD40 antibody. In this study of patients with atopic dermatitis and high IgE levels, we have analyzed the role of the CD40 molecule in IgE production. Costimulation of peripheral blood mononuclear cells (PBMCs) from normal donors with interleukin-4 (IL-4) and anti-CD40 monoclonal antibody resulted in a selective increase in IgE production; either reagent alone, however, was ineffective. In contrast, addition of anti-CD40 monoclonal antibody alone to PBMCs or B cells from patients with atopic dermatitis markedly increased IgE production, even in the absence of exogenous IL-4. With the use of an ELISA spot assay, this increase in IgE production was attributed to an expansion of IgE-secreting B cells. In anti-IgM-stimulated lymphocyte cultures from patients with atopic dermatitis the costimulation with anti-CD40 induced strong lymphocyte proliferation. Similar results were observed with anti-IgM plus IL-4. The augmentation induced by anti-CD40 was inhibited by addition of anti-IL4 to anti-CD40-treated atopic dermatitis cells. In normal subjects the effects of anti-CD40 alone on IgE production could be observed after pretreatment of normal PBMCs with IL-4 for 3 days. The effects of anti-CD40 in atopic dermatitis may be explained in part by differences in CD40 expression. In freshly isolated PBMCs from patients with atopic dermatitis, the mean fluorescence intensity of CD40 expression on B cells was increased when compared with PBMCs from nonatopic donors, ans stimulation of normal or atopic dermatitis PBMCs with IL-4 increased the intensity of CD40 staining of cells.