Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Identification of the breast cancer susceptibility gene BRCA2

In Western Europe and the United States approximately 1 in 12 women develop breast cancer. A small proportion of breast cancer cases, in particular those arising at a young age, are attributable to a highly penetrant, autosomal dominant predisposition to the disease. The breast cancer susceptibility gene, BRCA2, was recently localized to chromosome 13q12-q13. Here we report the identification of a gene in which we have detected six different germline mutations in breast cancer families that are likely to be due to BRCA2. Each mutation causes serious disruption to the open reading frame of the transcriptional unit. The results indicate that this is the BRCA2 gene.

LMNA, encoding lamin A/C, is mutated in partial lipodystrophy

The lipodystrophies are a group of disorders characterized by the absence or reduction of subcutaneous adipose tissue. Partial lipodystrophy (PLD; MIM 151660) is an inherited condition in which a regional (trunk and limbs) loss of fat occurs during the peri-pubertal phase. Additionally, variable degrees of resistance to insulin action, together with a hyperlipidaemic state, may occur and simulate the metabolic features commonly associated with predisposition to atherosclerotic disease. The PLD locus has been mapped to chromosome 1q with no evidence of genetic heterogeneity. We, and others, have refined the location to a 5.3-cM interval between markers D1S305 and D1S1600 (refs 5, 6). Through a positional cloning approach we have identified five different missense mutations in LMNA among ten kindreds and three individuals with PLD. The protein product of LMNA is lamin A/C, which is a component of the nuclear envelope. Heterozygous mutations in LMNA have recently been identified in kindreds with the variant form of muscular dystrophy (MD) known as autosomal dominant Emery-Dreifuss MD (EDMD-AD; ref. 7) and dilated cardiomyopathy and conduction-system disease (CMD1A). As LMNA is ubiquitously expressed, the finding of site-specific amino acid substitutions in PLD, EDMD-AD and CMD1A reveals distinct functional domains of the lamin A/C protein required for the maintenance and integrity of different cell types.

Control of nitrogen export from watersheds by headwater streams

A comparative (15)N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export downstream less than half of the input of dissolved inorganic nitrogen from their watersheds.

Cytokine levels in the cerebrospinal fluid and serum of patients with multiple sclerosis

Interleukin (IL) 1 beta, tumor necrosis factor alpha (TNF alpha), and IL-6 are cytokines which mediate cellular responses during immune activation and inflammation. In multiple sclerosis (MS) they might be responsible for T-cell activation (IL-1 beta), for demyelination (TNF alpha), and for immunoglobulin (Ig) synthesis (IL-6) within the central nervous system. We studied IL-1 beta, TNF alpha, and IL-6 levels in the cerebrospinal fluid (CSF) of 34 patients with MS, 43 patients with non-inflammatory neurological diseases (NIND), and 19 patients with inflammatory neurological diseases (IND). IL-6 was found in the CSF of 29% of MS, 7% of NIND, and 47% of IND patients. TNF alpha was detected in the CSF of 23% of MS, 7% of NIND, and 29% of IND. CSF IL-6 and TNF alpha levels were significantly higher in MS and IND than in NIND. IL-1 beta was rarely detected in the CSF of any group. At least one cytokine was detected in 52% of MS CSF, 11% of NIND CSF, and 64% of IND CSF. In MS patients, no relationship was observed between the incidence or the amount of intrathecal IgG synthesis or oligoclonal bands and the presence of any cytokine. We also evaluated cytokine levels in paired sera from 11 MS and 13 NIND patients. Low levels of IL-6 were detected in most sera from MS and NIND patients. TNF alpha was detected in only two MS sera, and IL-1 beta was undetectable in any sample. Our results indicate that increased CSF levels of the cytokines IL-6 and TNF alpha occur frequently in MS and IND, but there is no obvious relationship to intrathecal Ig synthesis.

Mutations in SLC19A2 cause thiamine-responsive megaloblastic anaemia associated with diabetes mellitus and deafness

Thiamine-responsive megaloblastic anaemia (TRMA), also known as Rogers syndrome, is an early onset, autosomal recessive disorder defined by the occurrence of megaloblastic anaemia, diabetes mellitus and sensorineural deafness, responding in varying degrees to thiamine treatment (MIM 249270). We have previously narrowed the TRMA locus from a 16-cM to a 4-cM interval on chromosomal region 1q23.3 (refs 3,4) and this region has been further refined to a 1.4-cM interval. Previous studies have suggested that deficiency in a high-affinity thiamine transporter may cause this disorder. Here we identify the TRMA gene by positional cloning. We assembled a P1-derived artificial chromosome (PAC) contig spanning the TRMA candidate region. This clarified the order of genetic markers across the TRMA locus, provided 9 new polymorphic markers and narrowed the locus to an approximately 400-kb region. Mutations in a new gene, SLC19A2, encoding a putative transmembrane protein homologous to the reduced folate carrier proteins, were found in all affected individuals in six TRMA families, suggesting that a defective thiamine transporter protein (THTR-1) may underlie the TRMA syndrome.

Degenerate perturbations of protein structure as the mechanism of anaesthetic action

The interaction of the n-alkanols with lipid bilayers and excitable membranes shows that there is no simple correlation between conduction block and any of the perturbations of bilayer structure currently proposed as unitary mechanisms of local anaesthetic action. We propose instead that the n-alkanols act by direct interaction with target proteins to cause perturbations which depend directly on the precise structure of the alcohol.

Measurement of apoptosis, proliferation and three cytokines in 46 patients with myelodysplastic syndromes

Extensive apoptosis or programmed cell death (PCD) of both hematopoietic (erythroid, myeloid, megakaryocytic) and stromal cells in myelodysplastic syndromes (MDS) cancels the high birth-rate resulting in ineffective hematopoiesis and has been demonstrated as the probable basis for peripheral cytopenias in MDS by our group. It is proposed that factors present in the microenvironment are inducing apoptosis in all the cells whether stromal or parenchymal. To investigate this hypothesis further, bone marrow biopsies from 46 MDS patients and eight normal individuals were examined for the presence of three cytokines, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and granulocyte macrophage-colony stimulating factor (GM-CSF) and one cellular component, macrophages, by the use of monoclonal antibodies immunohistochemically. Results showed the presence of TNF-alpha and TGF-beta in 41/46 and 40/46 cases of MDS respectively, while only 15 cases showed the presence of GM-CSF. Further a significant direct relationship was found between the degree of TNF-alpha and the incidence of PCD (p= 0.0015). Patients who showed high PCD also had an elevated TNF-alpha level. Thus, the expression of high amounts of TNF-alpha and TGF-beta and low amounts of the viability factor GM-CSF may be responsible for the high incidence of PCD leading to ineffective hematopoiesis in MDS. Future studies will be directed at attempting to reverse the lesion in MDS by using anti-TNF-alpha drugs such as pentoxifylline.

Cytokines in the vitreous of patients with proliferative diabetic retinopathy

Sixteen vitreous and paired serum samples from 13 patients with proliferative diabetic retinopathy, vitreous samples from seven cadaveric control subjects, and aqueous humor samples from 15 normal control subjects were assayed for the cytokines interleukin-1, tumor necrosis factor-alpha, interleukin-6, and interferon-gamma. Interleukin-6 was detected in 15 of 16 vitreous samples (94%) from diabetic patients, but it was not detected in any of the aqueous humor samples. Vitreous interleukin-6 levels positively correlated with ocular disease activity. Interleukin-1 was detected in seven of 16 vitreous samples (44%) and in four of ten aqueous humor samples (40%), whereas tumor necrosis factor-alpha and interferon-gamma were never detected in vitreous or aqueous fluid. Serum samples from diabetic patients and control subjects contained comparable low levels of interleukin-6. Interleukin-1, tumor necrosis factor-alpha, and interferon-gamma were not found in any of the sera. Because interleukin-6 can function as B-cell differentiation factor, this cytokine may have a role in immunoglobulin deposition in the ocular tissues and in the immunopathologic characteristics of proliferative retinopathy.

A functional polymorphism of toll-like receptor 4 is not associated with likelihood or severity of meningococcal disease

Human Toll-like receptor 4 (TLR4) transduces proinflammatory cytokine release by human cells in response to lipopolysaccharide (LPS). This study tested the hypothesis that, if TLR4 is rate limiting for a successful response to bacterial LPS in humans, a human gene polymorphism that results in the amino acid substitution Asp299Gly and causes reduced expression and function of TLR4 should influence susceptibility to or severity of natural gram-negative infection. The allele frequency of the Asp299Gly polymorphism was 5.9% among 879 blood donors, 6.5% among 1047 patients with microbiologically proven meningococcal disease, and 4.1% among 86 patients who died of meningococcal disease. No significant differences were observed, including those analyzed after stratification of the infected population by age and by meningococcal serogroup. Therefore, this functional TLR4 polymorphism does not influence susceptibility to or severity of meningococcal disease.

Reduction of globotriaosylceramide in Fabry disease mice by substrate deprivation

We used a potent inhibitor of glucosylceramide synthase to test whether substrate deprivation could lower globotriaosylceramide levels in alpha-galactosidase A (alpha-gal A) knockout mice, a model of Fabry disease. C57BL/6 mice treated twice daily for 3 days with D-threo-1-ethylendioxyphenyl-2-palmitoylamino-3-pyrrolidi no-propanol (D-t-EtDO-P4) showed a concentration-dependent decrement in glucosylceramide levels in kidney, liver, and spleen. A single intraperitoneal injection of D-t-EtDO-P4 resulted in a 55% reduction in renal glucosylceramide, consistent with rapid renal glucosylceramide metabolism. A concentration-dependent decrement in renal and hepatic globotriaosylceramide levels was observed in alpha-Gal A(-) males treated for 4 weeks with D-t-EtDO-P4. When 8-week-old alpha-Gal A(-) males were treated for 8 weeks with 10 mg/kg twice daily, renal globotriaosylceramide fell to below starting levels, consistent with an alpha-galactosidase A-independent salvage pathway for globotriaosylceramide degradation. Complications observed with another glucosylceramide synthase inhibitor, N-butyldeoxynojirimycin, including weight loss and acellularity of lymphatic organs, were not observed with D-t-EtDO-P4. These data suggest that Fabry disease may be amenable to substrate deprivation therapy.

The Nottingham study of neurotic disorder: comparison of drug and psychological treatments

210 psychiatric outpatients with generalised anxiety disorder (71), or panic disorder (74), or dysthymic disorder (65) diagnosed by an interview schedule for DSM-III were allocated by constrained randomisation to one of five treatments: diazepam (28), dothiepin (28), placebo (28), cognitive and behaviour therapy (84), and a self-help treatment programme (42). All treatments were given for 6 weeks and then withdrawn by 10 weeks. Ratings of psychopathology were made by psychiatric assessors blind to both treatment and diagnosis before treatment and at 2, 4, 6, and 10 weeks after randomisation. 18 patients had insufficient data for analysis because of early drop-out. There were no important differences in treatment response between the diagnostic groups, but diazepam was less effective than dothiepin, cognitive and behaviour therapy, or self-help, these three treatments being of similar efficacy. Significantly more patients in the placebo group took additional psychotropic drugs in the 10 week period, and those allocated to dothiepin and cognitive and behaviour therapy took the least.

Novel insights into the biology of myelodysplastic syndromes: excessive apoptosis and the role of cytokines

The paradox of myelodysplastic syndromes (MDS) which present with pancytopenias despite cellular bone marrows (BM) was investigated by conducting detailed studies of proliferation and apoptosis in 89 MDS patients. Our results demonstrated a rapid rate of both proliferation as well as apoptosis. Levels of three cytokines, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and interleukin-1 beta (IL-1 beta) were measured in the same patients. High levels of TNF-alpha were found to correlate with high levels of apoptosis in 83 MDS patients (P = 0.0045). We propose a dual role for TNF-alpha (or other cytokines) in the pathogenesis of MDS. On the one hand, TNF-alpha induces apoptosis in the maturing cells causing pancytopenia while on the other, it stimulates the proliferation of the primitive progenitors accounting for the hypercellular BM frequently seen in MDS. A new model for MDS is presented. The initial abnormality probably affects a primitive hemopoietic progenitor which acquires a growth advantage leading to monoclonal hemopoiesis, which in turn makes these cells susceptible towards acquiring additional mutations and appearance of cytogenetically marked (or unmarked) clones. Cytokines such as TNF-alpha whose source is presently unknown, then contribute towards the clinical syndrome of pancytopenia and hypercellularity.

Simultaneous assessment of cell kinetics and programmed cell death in bone marrow biopsies of myelodysplastics reveals extensive apoptosis as the probable basis for ineffective hematopoiesis

Despite hypercellular bone marrows (BM), peripheral cytopenias are the rule in patients with myelodysplastic syndromes (MDS). This study examined the roles played by cell birth and cell death rates in generating this paradox. Cell kinetics from BM biopsies of 35 MDS patients were measured using intravenous infusions of either iododeoxyuridine or bromodeoxyuridine, or both. Degree of apoptosis or programmed cell death (PCD) was estimated using in situ end-labeling of DNA directly from BM biopsies, which were simultaneously double-labeled from proliferation/PCD. MDS were found to be highly proliferative disorders with large numbers of myeloid, erythroid, and megakaryocytic cells synthesizing DNA. Median cycling time (Tc) of myeloblasts was more rapid than that of patients with acute myeloid leukemia (44.1 hr vs. 56.0 hr). Interestingly, most marrow cells of all three lineages in 32 of 34 evaluable cases were undergoing PCD. In 19 of 32 patients, greater than 75% cells were apoptotic. Surprisingly, large numbers of S-phase cells were found to be simultaneously undergoing PCD, as were stromal cells of the BM microenvironment. We conclude that the extensive apoptosis in hematopoietic cells effectively cancels the high birth rate resulting in ineffective hematopoiesis and accounting for deficient bone marrow function.

A compact mock circulation loop for the in vitro testing of cardiovascular devices

In vitro cardiovascular device performance evaluation in a mock circulation loop (MCL) is a necessary step prior to in vivo testing. A MCL that accurately represents the physiology of the cardiovascular system accelerates the assessment of the device's ability to treat pathological conditions. To serve this purpose, a compact MCL measuring 600 × 600 × 600 mm (L × W × H) was constructed in conjunction with a computer mathematical simulation. This approach allowed the effective selection of physical loop characteristics, such as pneumatic drive parameters, to create pressure and flow, and pipe dimensions to replicate the resistance, compliance, and fluid inertia of the native cardiovascular system. The resulting five-element MCL reproduced the physiological hemodynamics of a healthy and failing heart by altering ventricle contractility, vascular resistance/compliance, heart rate, and vascular volume. The effects of interpatient anatomical variability, such as septal defects and valvular disease, were also assessed. Cardiovascular hemodynamic pressures (arterial, venous, atrial, ventricular), flows (systemic, bronchial, pulmonary), and volumes (ventricular, stroke) were analyzed in real time. The objective of this study is to describe the developmental stages of the compact MCL and demonstrate its value as a research tool for the accelerated development of cardiovascular devices.

Hearing loss in very low birthweight infants treated with neonatal intensive care

The hearing of 111 perinatal intensive care survivors of birthweights 1500 g or less was assessed at a mean age of 6 1/2 years (range 4--12). These 111 infants included 86% of the long-term survivors of this birthweight cared for in the newborn unit of University College Hospital, London, during the years 1966--72. All these infants were nursed in commercially available incubators for periods ranging from 2 to 80 days (mean 37) in which the mean noise threshold was 65 dB. Ten (9%) had sensory neural nearing losses, one (1%) infant had a congenital conductive hearing loss, and 21 (19%) infants had exudative otitis media with a mean loss of 25 dB. Apnoeic attacks in the neotal period were the most significant predictors of hearing loss in these infants (P less than 0.05) and an indirect serum filirubin level of at least 170 micromol/l (10 mg/100 ml) in the neonatal period had an additive effect (P less than 0.05). There was no evidence that ambient noise had affected the hearing of these very low birthweight infants.

The Nottingham ECT Study. A double-blind comparison of bilateral, unilateral and simulated ECT in depressive illness

Sixty nine patients took part in a double-blind study to investigate the efficacy of bilateral, unilateral, and simulated ECT in the treatment of depressive illness. The findings suggest that both bilateral and unilateral ECT are highly effective treatments for depression and are significantly superior to simulated ECT. There was also evidence that patients receiving bilateral ECT recovered more rapidly than those receiving unilateral ECT and required significantly fewer treatments. The relevance of these findings to clinical practice is discussed.

Postural change of forced vital capacity predicts some respiratory symptoms in ALS

The detection of respiratory muscle weakness in ALS is necessary to plan initiation of noninvasive positive pressure ventilation and begin discussion of advanced directives. The authors measured the erect seated and supine forced vital capacity (FVC) in 38 patients with ALS and 15 controls. The supine FVC is significantly lower and the erect--supine FVC difference is significantly greater in patients with complaints of dyspnea, orthopnea, and daytime fatigue.

Evaluation of accelerator mass spectrometry in a human mass balance and pharmacokinetic study-experience with 14C-labeled (R)-6-[amino(4- chlorophenyl)(1-methyl-1H-imidazol-5-yl)methyl]-4-(3-chlorophenyl)-1- methyl-2(1H)-quinolinone (R115777), a farnesyl transferase inhibitor

Accelerator mass spectrometry (AMS) has been used in a human mass balance and metabolism study to analyze samples taken from four healthy male adult subjects administered nanoCurie doses of the farnesyl transferase inhibitor 14C-labeled (R)-6-[amino(4-chlorophenyl)(1-methyl-1H-imidazol-5-yl)methyl]-4-(3-chlorophenyl)-1-methyl-2(1H)-quinolinone ([14C]R115777). Plasma, urine, and feces samples were collected at fixed timepoints after oral administration of 50 mg [14C]R115777 (25.4 Bq/mg or 687 pCi/mg i.e., equivalent to 76.257 x 10(3) dpm) per subject. AMS analysis showed that drug-related (14)C was present in the plasma samples with C(max) values ranging from 1.6055 to 2.9074 dpm/ml (1.0525-1.9047 microg/ml) at t(max) = 2 to 3 h. The C(max) values for acetonitrile extracts of plasma samples ranged from 0.3724 to 0.7490 dpm/ml in the four male subjects. Drug-related 14C was eliminated from the body both in the urine and the feces, with a mean total recovery of 79.8 +/- 12.9% in the feces and 13.7 +/- 6.2% in the urine. The majority of drug-related radioactivity in urine and feces was excreted within the first 48 h. High-performance liquid chromatography (HPLC)-AMS profiles were generated from radioactive parent drug plus metabolites from pooled diluted urine, plasma, and methanolic feces extracts and matched to retention times of synthetic reference substances, postulated as metabolites. All HPLC separations used no more than 5 dpm injected on-column. The radioactive metabolite profiles obtained compared well with those obtained using liquid chromatography/tandem mass spectometry. This study demonstrates the use of AMS in a human phase I study in which the administered radioactive dose was at least 1000-fold lower than that used for conventional radioactive studies.

Delayed traumatic intracerebral hematoma: report of 15 cases operatively treated

Fifteen cases of delayed traumatic intracerebral hematoma (DTICH) operatively treated are reported. Patients who are awake or only drowsy on admission (Coma Grades 1 and 2, Grady scale) often undergo dramatic sudden neurological deterioration 48 to 72 hours after admission. Emergency computed tomographic scanning and prompt craniotomy for hematoma evacuation yield excellent clinical results in the majority of cases. Patients presenting in deeper grades of coma (Grades 3 to 5, Grady scale) who develop DTICH do quite poorly, often because the diagnosis is difficult to make and consequently is delayed. The development of DTICH is in our experience highly unpredictable, and often no clear secondary cause (hypercapnia, hypoxia, bleeding diathesis) can be demonstrated.

Comparison of the absorption of micronized (Daflon 500 mg) and nonmicronized 14C-diosmin tablets after oral administration to healthy volunteers by accelerator mass spectrometry and liquid scintillation counting

Daflon 500 mg, is a micronized purified flavonoid fraction, containing 90% w/w diosmin and 10% w/w of flavonoids expressed as hesperidin, used clinically in the treatment of chronic venous insufficiency and hemorrhoidal disease. This study was designed to investigate the influence of particle size on the overall absorption of diosmin after oral administration of micronized (mean particle size = 1.79 microm, with 80% of particles having a size lower than 3.45 microm) and nonmicronized diosmin (mean particle size = 36.5 microm, with 80% of particles comprised between 19.9 and 159 microm). In a double blinded, cross-over study design, 500 mg tablets containing trace amounts (approximately 25 nCi) of (14)C-diosmin were administered to 12 healthy male volunteers as a single oral dose. Accelerator mass spectrometry and liquid scintillation counting were used for the measurement of (14)C-diosmin in urine and feces. Absorption of (14)C-diosmin from the gastrointestinal tract, measured by the urinary excretion of total radioactivity, was significantly improved with the micronized (57.9 +/- 20.2%) compared with the nonmicronized material (32.7 +/- 18.8%). Statistical comparison of the urinary excretion of the two pharmaceutical formulations showed this difference to be highly significant (p = 0.0004, analysis of variance). The overall excretion of the radiolabeled dose was 100% with mean +/- SD of 109 +/- 23% and 113 +/- 20% for the micronized and nonmicronized forms, respectively. The results of this study show: 1. the impact of a reduction of particle size on the extent of absorption of diosmin, giving a pharmacokinetic explanation to the better clinical efficacy observed with the micronized formulation, and 2. the use of accelerator mass spectrometry in conjunction with liquid scintillation counting in measurement of bioavailability in a human cross-over study comparing two drug formulations containing trace amounts of radioactivity.

Approach to communication, speech perception and intelligibility after paediatric cochlear implantation

The aim of this study was to explore the relationship between approach to communication, speech perception and speech intelligibility after cochlear implantation of young children with profound early deafness. A prospective speech perception and speech intelligibility assessment was undertaken on a consecutive group of implanted children. There were 46 children at the three-year, 26 at the four-year and 20 at the five-year intervals. All had been born deaf or deafened before the age of three and received cochlear implants before the age of seven. Their speech perception ability and the intelligibility of their speech were measured before cochlear implantation and annually thereafter. The children's communication had been classified by their teachers of the deaf at each interval into one of two categories: those using an oral approach and those using a signing approach. Results revealed that at all intervals, those children classified as using oral communication significantly exceeded those using signed communication on measures of speech perception and intelligibility (p<0.05). When those children who had changed from signed to oral communication were compared at the three-year interval with those who used oral communication throughout, there was no significant difference in their results. However, it remains to be explored whether children use oral communication after cochlear implantation because they are doing well, or whether they do well because they are using oral communication.

Mechanical circulatory support in the new era: an overview

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Genes for interleukin 7 are transcribed in leukemic cell subsets of individuals with chronic lymphocytic leukemia

Regulation of expression of interleukin 7 (IL-7) mRNA is aberrant in the leukemic subset of cells of chronic lymphocytic leukemia (CLL) patients. The entire coding sequence for IL-7 as well as an alternatively spliced IL-7 mRNA are transcribed in these leukemic cells. No IL-7 mRNA expression is detected in fresh peripheral blood mononuclear cells from normal individuals. Furthermore, the "normal" nonleukemic subsets of cells isolated from the same CLL patients also do not express IL-7 mRNA. The only subset of cells in which IL-7 mRNA is detected is the one that contains the leukemic cells themselves. The polymerase chain reaction was used to examine cytokine expression, and flow cytometry was used to purify the various subsets of peripheral blood mononuclear cells examined in these studies, as well as to examine IL-7 receptor expression. A proportion of the cells from the CLL patients express receptors that are capable of binding IL-7, whereas T cell-depleted normal cell preparations do not express receptors for IL-7 that are detectable with IL-7 fluorokines. The IL-7 receptor-bearing cells in CLL patients include a portion of leukemic cells and a fraction of the T cells, as well as some non-T, non-B cells. These findings suggest that IL-7 and IL-7 receptor expression in CLL may be relevant not only to growth regulation of the leukemic cells but to the immunological abnormalities that occur in the disease as well, possibly via the induction of inappropriate immune activity of IL-7 receptor-bearing cells.