Case fatality and population mortality associated with anaphylaxis in the United States.

BACKGROUND: Anaphylaxis is a serious allergic reaction that can cause death; however, the actual risk of death is unclear. OBJECTIVE: We sought to estimate the case fatality rate among hospitalizations or emergency department (ED) presentations for anaphylaxis and the mortality rate associated with anaphylaxis for the general population. METHODS: This was a population-based epidemiologic study using 3 national databases: the Nationwide Inpatient Sample (NIS; 1999-2009), the Nationwide Emergency Department Sample (NEDS; 2006-2009), and Multiple Cause of Death Data (MCDD; 1999-2009). Sources for these databases are hospital and ED discharge records and death certificates, respectively. RESULTS: Case fatality rates were between 0.25% and 0.33% among hospitalizations or ED presentations with anaphylaxis as the principal diagnosis (NIS+NEDS, 2006-2009). These rates represent 63 to 99 deaths per year in the United States, approximately 77% of which occurred in hospitalized patients. The rate of anaphylaxis-related hospitalizations increased from 21.0 to 25.1 per million population between 1999 and 2009 (annual percentage change, 2.23%; 95% CI, 1.52% to 2.94%), contrasting with a decreasing case fatality rate among hospitalizations (annual percentage change, -2.35%; 95% CI, -4.98% to 0.34%). Overall mortality rates ranged from 0.63 to 0.76 per million population (186-225 deaths per year, MCDD) and appeared stable in the last decade (annual percentage change, -0.31%; 95% CI, -1.54% to 0.93%). CONCLUSION: From 2006 to 2009, the overwhelming majority of hospitalizations or ED presentations for anaphylaxis did not result in death, with an average case fatality rate of 0.3%. Anaphylaxis-related hospitalizations increased steadily in the last decade (1999-2009), but this increase was offset by the decreasing case fatality rate among those hospitalized; both inpatient and overall mortality rates associated with anaphylaxis appeared stable and were well under 1 per million population. Although anaphylactic reactions are potentially life-threatening, the probability of dying is actually very low. With the prevalence of anaphylaxis on the increase, practitioners need to stay vigilant and follow the treatment guidelines to further reduce anaphylaxis-related deaths.

Review of outcomes after cessation of gonadotropin-releasing hormone agonist treatment of girls with precocious puberty.

Although gonadotropin-releasing hormone agonists (GnRHa) have been the standard of care of central precocious puberty (CPP) management for many years, there are still questions about the long-term consequences of treatment. With increased utilization of GnRHa treatment, it is now possible to assess posttreatment outcomes in the immediate posttreatment period and into adulthood. This literature review reports on the long-term effects of GnRHa therapy in girls with CPP after therapy has been discontinued. Published reports confirm the reversibility of hypothalamic-pituitary-ovarian axis suppression in females after cessation of GnRHa therapy, with the majority of patients achieving ovulatory menstrual cycles of normal timing and duration. GnRHa therapy does not appear to induce polycystic ovary syndrome or have long-term negative repercussions on either bone mineral density or body composition. Evidence is currently insufficient to identify agent-specific differences in outcomes, reproductive function, and health of offspring.

CCL5-CCR5 interaction provides antiapoptotic signals for macrophage survival during viral infection.

Host defense against viruses probably depends on targeted death of infected host cells and then clearance of cellular corpses by macrophages. For this process to be effective, the macrophage must presumably avoid its own virus-induced death. Here we identify one such mechanism. We show that mice lacking the chemokine Ccl5 are immune compromised to the point of delayed viral clearance, excessive airway inflammation and respiratory death after mouse parainfluenza or human influenza virus infection. Virus-inducible levels of Ccl5 are required to prevent apoptosis of virus-infected mouse macrophages in vivo and mouse and human macrophages ex vivo. The protective effect of Ccl5 requires activation of the Ccr5 chemokine receptor and consequent bilateral activation of G(alphai)-PI3K-AKT and G(alphai)-MEK-ERK signaling pathways. The antiapoptotic action of chemokine signaling may therefore allow scavengers to finally stop the host cell-to-cell infectious process.

Renal impairment, hypertension and plasma urotensin II.

BACKGROUND: Human urotensin II (UII) is a potent mammalian vasoconstrictor thought to be produced and cleared by the kidneys. Conflicting data exist regarding the relationship between UII concentrations, kidney function and blood pressure (BP). We measured the associations between kidney function [including end-stage renal disease (ESRD)] and levels of BP with plasma concentrations of UII. METHODS: Ninety-one subjects were enrolled. Thirty-one subjects had ESRD (undergoing haemodialysis), 30 subjects had chronic kidney disease (CKD) and 30 control subjects had no kidney disease. Plasma UII concentrations were measured by radioimmunoassay. RESULTS: Mean plasma UII concentrations were highest in controls, lower in subjects with ESRD and lowest in subjects with non-ESRD CKD (P<0.0001). UII concentrations correlated negatively with serum creatinine (P=0.0012) and CKD stage, and positively with creatinine clearance (P=0.013). In ESRD subjects, plasma UII (P=0.008) increased after dialysis, while SBP (P=0.007), DBP (P=0.009), serum creatinine (P<0.0001) and serum urea nitrogen (P<0.0001) decreased. UII concentrations were lower in patients with a history of hypertension (HTN) (P=0.016). Age, race and gender did not appear to be associated with UII concentration. However, the distribution of African American race and male gender appear to be associated with increasing stages of chronic kidney disease. CONCLUSIONS: These data suggest a potential vasodilatory role of UII in humans with kidney disease or hypertension. The reduction in UII levels in CKD also suggests either reduced production or greater clearance, or both, of UII.

Digoxin immune fab treatment for severe preeclampsia.

We evaluated the efficacy, safety, and biological mechanisms of digoxin immune Fab (DIF) treatment of severe preeclampsia. Fifty-one severe preeclamptic patients were randomized in double-blind fashion to DIF ( N = 24) or placebo ( N = 27) for 48 hours. Primary outcomes were change in creatinine clearance (CrCl) at 24 to 48 hours and antihypertensive drug use. Serum sodium pump inhibition, a sequela of endogenous digitalis-like factors (EDLF), was also assessed. CrCl in DIF subjects was essentially unchanged from baseline versus a decrease with placebo (-3 +/- 10 and -34 +/- 10 mL/min, respectively, P = 0.02). Antihypertensive use was similar between treatments (46 and 52%, respectively, P = 0.7). Serum sodium pump inhibition was decreased with DIF compared with placebo at 24 hours after treatment initiation (least squares mean difference, 19 percentage points, P = 0.03). DIF appeared to be well tolerated. These results suggest DIF prevents a decline in renal function in severe preeclampsia by neutralizing EDLF. Sodium pump inhibition was significantly improved. Further research is warranted.

A New Oral Testosterone Undecanoate Formulation Restores Testosterone to Normal Concentrations in Hypogonadal Men.

CONTEXT: A novel formulation of oral testosterone (T) undecanoate (TU) was evaluated in a phase 3 clinical trial. OBJECTIVE: Determine efficacy, short-term safety, and alignment of new oral TU formulation with current US approval standards for T replacement therapy. DESIGN: Randomized, active-controlled, open-label study. SETTING AND PATIENTS: Academic and private clinical practice sites; enrolled patients were clinically hypogonadal men 18 to 65 years old. METHODS: Patients were randomized 3:1 to oral TU, as prescribed (JATENZO®; n = 166) or a topical T product once daily (Axiron®; n = 56) for 3 to 4 months. Dose titration was based on average T levels (Cavg) calculated from serial pharmacokinetic (PK) samples. T was assayed by liquid chromatography-mass spectrometry/mass spectrometry. Patients had 2 dose adjustment opportunities prior to final PK visit. Safety was assessed by standard clinical measures, including ambulatory blood pressure (BP). RESULTS: 87% of patients in both groups achieved mean T Cavg in the eugonadal range. Sodium fluoride-ethylenediamine tetra-acetate plasma T Cavg (mean ± standard deviation) for the oral TU group was 403 ± 128 ng/dL (~14 ± 4 nmol/L); serum T equivalent, ~489 ± 155 ng/dL (17 ± 5 nmol/L); and topical T, 391 ± 140 ng/dL (~14 ± 5 nmol/L). Modeling/simulation of T PK data demonstrated that dose titration based on a single blood sample 4 to 6 h after oral TU dose yielded efficacy (93%) equivalent to Cavg-based titration (87%). Safety profiles were similar in both groups, but oral TU was associated with a mean increase in systolic BP of 3 to 5 mm Hg. CONCLUSION: A new oral TU formulation effectively restored T to mid-eugonadal levels in hypogonadal patients.

Comparison of non-digitalis binding properties of digoxin-specific Fabs using direct binding methods.

Digibind and DigiFab are commercial formulations of polyclonal, ovine, digoxin-specific Fabs in clinical use for treatment of digoxin intoxication. Of interest for extending its use to other clinical indications, Digibind has also been reported to neutralize the effect of endogenous digoxin-like molecules, including ouabain, that are linked to clinical disorders ranging from preeclampsia to congestive heart failure. Although Digibind and DigiFab are equivalent in their digoxin-binding activity, the antigens used to produce these Fabs are different. We therefore explored, using native (3)H-digoxin and (3)H-ouabain in four different types of solution-phase binding methods, whether they might exhibit different profiles with respect to ouabain and other digoxin-like factors. Consistent with previous results, both Fab preparations bound digoxin with the same affinities and capacities. However, (3)H-ouabain was found to bind with high affinity only to Fab sub-populations present in both products. Interestingly, this sub-population was twice as large for Digibind compared to DigiFab. Competition experiments also showed differences in specificity within Fab sub-populations. Therefore, the equivalence in digoxin-binding activity of the two Fab preparations does not extend to ouabain-binding capacity and Fab specificity, with implications for clinical differentiation between the preparations in treatment of disorders related to control of non-digoxin cardenolides. The existence of a small but perhaps clinically relevant sub-population of antibodies was detected using specific radioligands. This sub-population could not have been detected nor quantified using standard cross-reactivity in an ELISA assay.

The CoLaus study: a population-based study to investigate the epidemiology and genetic determinants of cardiovascular risk factors and metabolic syndrome.

BACKGROUND: Cardiovascular diseases and their associated risk factors remain the main cause of mortality in western societies. In order to assess the prevalence of cardiovascular risk factors (CVRFs) in the Caucasian population of Lausanne, Switzerland, we conducted a population-based study (Colaus Study). A secondary aim of the CoLaus study will be to determine new genetic determinants associated with CVRFs. METHODS: Single-center, cross-sectional study including a random sample of 6,188 extensively phenotyped Caucasian subjects (3,251 women and 2,937 men) aged 35 to 75 years living in Lausanne, and genotyped using the 500 K Affymetrix chip technology. RESULTS: Obesity (body mass index > or = 30 kg/m2), smoking, hypertension (blood pressure > or = 140/90 mmHg and/or treatment), dyslipidemia (high LDL-cholesterol and/or low HDL-cholesterol and/or high triglyceride levels) and diabetes (fasting plasma glucose > or = 7 mmol/l and/or treatment) were present in 947 (15.7%), 1673 (27.0%), 2268 (36.7%), 2113 (34.2%) and 407 (6.6%) of the participants, respectively, and the prevalence was higher in men than in women. In both genders, the prevalence of obesity, hypertension and diabetes increased with age. CONCLUSION: The prevalence of major CVRFs is high in the Lausanne population in particular in men. We anticipate that given its size, the depth of the phenotypic analysis and the availability of dense genome-wide genetic data, the CoLaus Study will be a unique resource to investigate not only the epidemiology of isolated, or aggregated CVRFs like the metabolic syndrome, but can also serve as a discovery set, as well as replication set, to identify novel genes associated with these conditions.

Evidence that fibroblasts derive from epithelium during tissue fibrosis.

Interstitial fibroblasts are principal effector cells of organ fibrosis in kidneys, lungs, and liver. While some view fibroblasts in adult tissues as nothing more than primitive mesenchymal cells surviving embryologic development, they differ from mesenchymal cells in their unique expression of fibroblast-specific protein-1 (FSP1). This difference raises questions about their origin. Using bone marrow chimeras and transgenic reporter mice, we show here that interstitial kidney fibroblasts derive from two sources. A small number of FSP1(+), CD34(-) fibroblasts migrate to normal interstitial spaces from bone marrow. More surprisingly, however, FSP1(+) fibroblasts also arise in large numbers by local epithelial-mesenchymal transition (EMT) during renal fibrogenesis. Both populations of fibroblasts express collagen type I and expand by cell division during tissue fibrosis. Our findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate. As a general mechanism, this change in fate highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions.

Ethanol does not alter the pharmacokinetic profile of the controlled-release formulation of carvedilol.

The concomitant ingestion of alcohol may alter the release of a drug from a modified-release dosage form, posing a potential risk to patients. In a randomized, open-label, 4-period cross-over study, the pharmacokinetic profiles of R(+) and S(-) carvedilol were compared after a single oral dose of carvedilol controlled-release formulation (administered following a standard meal) was given alone or concomitantly with ethanol. Thirty-nine healthy subjects participated in this study. Following coadministration of carvedilol controlled-release 40 mg with ethanol (approximately 38 g), ethanol ingestion 2 hours before or 2 hours after carvedilol controlled-release administration, area under the curve for the R(+) and S(-) carvedilol enantiomers was similar compared with carvedilol controlled-release given alone. Carvedilol exposure was not affected by the concomitant administration of ethanol and carvedilol controlled-release. Maximum plasma concentrations for the R(+) and S(-) carvedilol enantiomers were similar except when ethanol was ingested 2 hours after carvedilol controlled-release administration, where there was a modest decrease in maximum plasma concentration for R(+) and S(-) carvedilol (16% and 17%, respectively). Carvedilol controlled-release given alone or concomitantly with ethanol ingestion was generally well tolerated, and no serious or severe adverse events were reported. Ethanol did not alter the pharmacokinetic profile of carvedilol controlled-release.

Multiple dose pharmacokinetics of paroxetine in children and adolescents with major depressive disorder or obsessive-compulsive disorder.

The current study examined the pharmacokinetics (PK), safety, and tolerability of paroxetine after repeated multiple oral dosing in children and adolescents with major depressive or obsessive-compulsive disorder. In this 6-week, open-label, repeat dose, dose-rising study, 62 patients (27 children and 35 adolescents) were treated with paroxetine 10 mg/day for the first 2 weeks of the study, 20 mg/day for the next 2 weeks, and 30 mg/day for the final 2 weeks. Pharmacokinetic sampling and safety assessments occurred at baseline and subsequently on the final treatment day of each dosing level. Between-patient variability in PK was pronounced at the 10 mg dose level, but markedly reduced at higher doses. A supra-proportional increase in plasma concentrations with increasing dose was evident in both age groups. Data for C(max) and AUC(0-24) indicated that, at each dose level, paroxetine steady-state systemic exposure was higher in children than in adolescents. The differences between age groups, however, diminished with each increasing dose, and were virtually abolished when differences in weight among different age groups were considered. Stepwise regression analysis indicated that both oral clearance and volume of distribution were highly dependent on paroxetine dose, cytochrome P4502D6 genotype, and weight (p<0.0001), but not age or sex. Paroxetine was generally safe and well tolerated in both age groups, with the most frequently observed adverse events being largely consistent with those observed in prior paroxetine studies of adult psychiatric patients. Certain gastrointestinal and behavioral activation events (aggressive reaction and nervousness) were reported more frequently in the youngest age group.

Pharmacokinetic properties of a new controlled-release formulation of carvedilol.

This review summarizes the pharmacokinetics (PK) of carvedilol after administration of a new once-daily controlled-release (CR) formulation. The plasma concentration-time profiles for both R(+)- and S(-)-carvedilol indicate that carvedilol CR will provide coverage over a 24-hour period similar to the current immediate-release (IR) twice-daily formulation. Exposures for both enantiomers, based on area under the curve (AUC), maximum plasma concentrations (C(max)), and trough concentrations, are equivalent for carvedilol CR compared with carvedilol IR. C(max) and AUC of the enantiomers of carvedilol increase in an approximate dose-proportional manner after administration of carvedilol CR over the dose range of 10-80 mg, indicating that the formulation provides consistent PK performance across the dose strengths proposed for marketing. The intrasubject and intersubject variability of carvedilol CR was comparable to carvedilol IR. For carvedilol CR, mean AUC and C(max) were increased <20% after a high-fat meal compared with a standard meal. The CR and IR formulations of carvedilol exhibited equivalent steady-state PK characteristics in the target hypertension and heart failure populations. The availability of once-daily dosing is expected to improve treatment adherence and thereby enhance the effectiveness of carvedilol in routine clinical use.

Pharmacokinetic and pharmacodynamic comparison of controlled-release carvedilol and immediate-release carvedilol at steady state in patients with hypertension.

Carvedilol is indicated for the treatment of essential hypertension and mild-to-severe chronic heart failure, as well as the reduction of cardiovascular mortality in clinically stable post-myocardial infarction patients with left ventricular dysfunction. Carvedilol is a racemic mixture of R(+) and S(-) enantiomers that combines beta(1)-, beta(2)-, and alpha(1)-adrenoceptor blockade. For all indications, the immediate-release (IR) formulation of carvedilol is taken twice daily. A controlled-release (CR) formulation of carvedilol that allows once-daily dosing has recently been developed. In this double-blind, parallel-group, crossover study, 122 patients with essential hypertension were randomly allocated to receive low and high doses of carvedilol or placebo. Patients received either a constant low dose (CR 20 mg once daily or IR 6.25 mg twice daily) or were titrated to a high dose (CR 80 mg once daily or IR 25 mg twice daily) before being crossed over to an equivalent dose of the alternative formulation. The pharmacokinetic (PK) and pharmacodynamic (PD) profiles were compared between patients receiving carvedilol CR and carvedilol IR. The PK profiles for R(+)- and S(-)-carvedilol for the 2 formulations were equivalent (based on area under the curve, maximum plasma concentration [C(max)], and trough drug concentration). Consistent with an extended-release formulation, carvedilol CR delayed C(max) by 3.5 hours compared with carvedilol IR. For both carvedilol CR and IR, the attenuation of exercise-induced heart rate in patients with hypertension was maintained over the entire 24-hour period, and the 2 formulations demonstrated equivalent beta(1)-blocking effects at trough (end of the dosing interval [PD(min)]), suggesting that the rate of absorption does not interfere with the PD effect. In this first direct comparison of carvedilol CR and IR in subjects with hypertension, fewer adverse events were reported while subjects were receiving carvedilol CR (59.1% overall) compared with carvedilol IR (77.5% overall). This was true regardless of dose received. Headache was the most commonly reported adverse event for subjects receiving either formulation of carvedilol and placebo. Importantly, dizziness and headache were reported less often when subjects received carvedilol CR. This is the first study to show that both formulations had comparable beta(1)-adrenergic blockade in patients with essential hypertension under steady-state conditions. Notably, carvedilol CR provides consistent beta(1)-adrenergic blockade over 24 hours with a once-daily dose.

Random unstimulated pediatric luteinizing hormone levels are not reliable in the assessment of pubertal suppression during histrelin implant therapy.

BACKGROUND: Gonadotropin-releasing hormone agonist (GnRHa)-stimulated luteinizing hormone (LH) is the standard hormonal assessment for both diagnosis and therapeutic monitoring of children with central precocious puberty (CPP). Use of unstimulated (random) LH levels may be helpful in diagnosis and has gained popularity in monitoring GnRHa therapy despite lack of validation against stimulated values. The objective of this investigation was to assess the suitability of random LH for monitoring pubertal suppression during GnRHa treatment. METHODS: Data from a multi-year, multicenter, open-label trial of annual histrelin implants for CPP was used for our analysis. Children meeting clinical and hormonal criteria for CPP, either naïve to GnRHa therapy or previously treated with another GnRHa for at least 6 months who were being treated at academic pediatric centers were included in the study. Subjects received a single 50-mg subcutaneous histrelin implant annually until final explant at an age determined at the discretion of each investigator. Monitoring visits for physical examination and GnRHa-stimulation testing were performed at regular intervals. The main outcome measure was pubertal suppression during treatment defined by peak LH < 4 mIU/mL after GnRHa stimulation. RESULTS: During histrelin treatment, 36 children underwent a total of 308 monitoring GnRHa stimulation tests. Unstimulated and peak LH levels were positively correlated (r = 0.798), and both declined from the first to second year of treatment. Mean ± SD peak LH level during therapy was 0.62 ± 0.43 mIU/mL (range, 0.06-2.3), well below the normal prepubertal mean. Mean random LH was 0.35 ± 0.25 mIU/mL (range, 0.04-1.5), 10-fold higher than the normal prepubertal mean. The random LH levels were above the prepubertal upper threshold (<0.3 mIU/mL) in 48.4% of all tests and in 88.9% of subjects at some point during therapy. CONCLUSIONS: In contrast with GnRHa-stimulated LH, unstimulated LH values frequently fail to demonstrate suppression to prepubertal values during GnRHa therapy for CPP, despite otherwise apparent pubertal suppression, and are thus unsuitable for therapeutic monitoring. TRIAL REGISTRATION: ClinicalTrial.gov NCT00779103.

An orally active calcium-sensing receptor antagonist that transiently increases plasma concentrations of PTH and stimulates bone formation.

Daily subcutaneous administration of exogenous parathyroid hormone (PTH) promotes bone formation in patients with osteoporosis. Here we describe two novel, short-acting calcium-sensing receptor antagonists (SB-423562 and its orally bioavailable precursor, SB-423557) that elicit transient PTH release from the parathyroid gland in several preclinical species and in humans. In an ovariectomized rat model of bone loss, daily oral administration of SB-423557 promoted bone formation and improved parameters of bone strength at lumbar spine, proximal tibia and midshaft femur. Chronic administration of SB-423557 did not increase parathyroid cell proliferation in rats. In healthy human volunteers, single doses of intravenous SB-423562 and oral SB-423557 elicited transient elevations of endogenous PTH concentrations in a profile similar to that observed with subcutaneously administered PTH. Both agents were well tolerated in humans. Transient increases in serum calcium, an expected effect of increased parathyroid hormone concentrations, were observed post-dose at the higher doses of SB-423557 studied. These data constitute an early proof of principle in humans and provide the basis for further development of this class of compound as a novel, orally administered bone-forming treatment for osteoporosis.

Pharmacogenetics to predict drug-related adverse events.

Identification of reliable markers to predict drug-related adverse events (DRAEs) is an important goal of the pharmaceutical industry and others within the healthcare community. We have used genetic polymorphisms, including the most frequent source of variation (single nucleotide polymorphisms, SNPs) in the human genome, in pharmacogenetic approaches designed to predict DRAEs. Three studies exemplify the principles of using polymorphisms to identify associations in progressively larger genomic regions: polymorphic repeats within the UDP-glucuronysltransferase I (UGT1A1) gene in patients experiencing hyperbilirubinemia after administration of tranilast, an experimental drug to prevent re-stenosis following coronary revascularization; high linkage disequilibrium within the Apolipoprotein E (ApoE) gene in patients with Alzheimer Disease (AD); and the polymorphic variant HLA-B57 in patients with hypersensitivity reaction after administration of abacavir, a nucleoside reverse transcriptase inhibitor for the treatment of HIV. Together, these studies demonstrate in a stepwise manner the feasibility of using pharmacogenetic approaches to predict DRAEs.

Role of RANTES in the development of autoimmune tissue injuries in MRL-Fas lpr mice.

MRL-Fas lpr mice spontaneously develop a severe autoimmune disease closely resembling human SLE. To investigate the possible role of RANTES in autoimmune tissue injuries, we have constructed RANTES-deficient MRL-Fas lpr mice by gene targeting. In the RANTES-deficient mice, axillary lymph nodes were significantly reduced in size compared with those of RANTES-intact mice. Flow cytometric analysis revealed that double-negative (DN) T cells were significantly reduced. Image analyzer showed that cell-infiltrated areas in peribronchial lesions were decreased in the lung of RANTES-deficient MRL-Fas lpr mice. Furthermore, we detected continuous expression of RANTES mRNA in the lung of MRL-Fas lpr mice. In contrast, the degree of histological renal injuries and survival rate was similar in both genotypes. We speculate that RANTES is involved in the development of peribronchial pulmonary lesions in MRL-Fas lpr mice. Further studies using RANTES-deficient mice might contribute to the elucidation of the role of RANTES in autoimmune tissue injuries.

Impaired T cell function in RANTES-deficient mice.

The chemokine RANTES is a chemoattractant for monocytes and T cells and is postulated to participate in many aspects of the immune response. To evaluate the biological roles of RANTES in vivo, we generated RANTES-deficient (-/-) mice and characterized their T cell function. In cutaneous delayed-type hypersensitivity assays, a 50% reduction in ear and footpad swelling was seen in -/- mice compared to +/+ mice. In vitro, polyclonal and antigen-specific T cell proliferation was decreased. Quantitative analysis using the fluorescent dye carboxy-fluorescein succinimidyl ester revealed that this proliferative defect was due both to fewer antigen-reactive T cells and to a reduction in the capacity of these cells to proliferate. In addition, IFN-gamma and IL-2 production by the -/- T cells was dramatically decreased. Together, these data suggest that RANTES is required for normal T cell functions as well as for recruiting monocytes and T cells to sites of inflammation.