Updated European Consensus Statement on diagnosis and treatment of adult ADHD.

Background Attention-deficit/hyperactivity disorder (ADHD) is among the most common psychiatric disorders of childhood that often persists into adulthood and old age. Yet ADHD is currently underdiagnosed and undertreated in many European countries, leading to chronicity of symptoms and impairment, due to lack of, or ineffective treatment, and higher costs of illness. Methods The European Network Adult ADHD and the Section for Neurodevelopmental Disorders Across the Lifespan (NDAL) of the European Psychiatric Association (EPA), aim to increase awareness and knowledge of adult ADHD in and outside Europe. This Updated European Consensus Statement aims to support clinicians with research evidence and clinical experience from 63 experts of European and other countries in which ADHD in adults is recognized and treated. Results Besides reviewing the latest research on prevalence, persistence, genetics and neurobiology of ADHD, three major questions are addressed: (1) What is the clinical picture of ADHD in adults? (2) How should ADHD be properly diagnosed in adults? (3) How should adult ADHDbe effectively treated? Conclusions ADHD often presents as a lifelong impairing condition. The stigma surrounding ADHD, mainly due to lack of knowledge, increases the suffering of patients. Education on the lifespan perspective, diagnostic assessment, and treatment of ADHD must increase for students of general and mental health, and for psychiatry professionals. Instruments for screening and diagnosis of ADHD in adults are available, as are effective evidence-based treatments for ADHD and its negative outcomes. More research is needed on gender differences, and in older adults with ADHD.

The brains of high functioning autistic individuals do not synchronize with those of others.

Multifaceted and idiosyncratic aberrancies in social cognition characterize autism spectrum disorders (ASDs). To advance understanding of underlying neural mechanisms, we measured brain hemodynamic activity with functional magnetic resonance imaging (fMRI) in individuals with ASD and matched-pair neurotypical (NT) controls while they were viewing a feature film portraying social interactions. Pearson's correlation coefficient was used as a measure of voxelwise similarity of brain activity (InterSubject Correlations-ISCs). Individuals with ASD showed lower ISC than NT controls in brain regions implicated in processing social information including the insula, posterior and anterior cingulate cortex, caudate nucleus, precuneus, lateral occipital cortex, and supramarginal gyrus. Curiously, also within NT group, autism-quotient scores predicted ISC in overlapping areas, including, e.g., supramarginal gyrus and precuneus. In ASD participants, functional connectivity was decreased between the frontal pole and the superior frontal gyrus, angular gyrus, superior parietal lobule, precentral gyrus, precuneus, and anterior/posterior cingulate gyrus. Taken together these results suggest that ISC and functional connectivity measure distinct features of atypical brain function in high-functioning autistic individuals during free viewing of acted social interactions. Our ISC results suggest that the minds of ASD individuals do not 'tick together' with others while perceiving identical dynamic social interactions.

Total plasma l-tryptophan, free l-tryptophan and competing amino acid levels in a homicidal male adolescent with conduct disorder.

OBJECTIVE: Several studies have shown abnormal findings in human serotonin metabolism, such as increased total plasma l-tryptophan and free l-tryptophan levels among habitually violent antisocial offenders. It is not clear if these increased l-tryptophan levels are associated with adult antisocial personality disorder (ASP) or history of substance abuse, or if these levels are already present in adolescent subjects with conduct disorder (CD). METHOD: Total plasma and free l-tryptophan and competing amino acids (CAAs) were measured in a 15-year-old adolescent offender, who was convicted for two homicides, and in 10 healthy male controls of similar age and body mass index (BMI). RESULTS: In the juvenile offender, plasma total l-tryptophan/CAA was 84% and free l-tryptophan/CAA 143% higher than average mean among controls. CONCLUSION: From this very aggressive boy with CD, findings of free l- and total l-tryptophan/CAA values were similar to those of habitually violent adult ASP offenders. As severe CDs in adolescence tend to develop into adults with ASP, increased l-tryptophan/CAA and free l-tryptophan/CAA values may serve as early indicators for the development of habitually violent adult offenders.

Prospective evaluation of the immunobead assay for the diagnosis of adult chronic immune thrombocytopenic purpura (ITP).

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by antibody-induced platelet destruction. To better define the role of antigen-specific assays in adult chronic ITP, we prospectively measured platelet-associated autoantibody against either glycoprotein (GP) IIb/IIIa or GPIb/IX in 282 patients with chronic ITP and 289 patients with thrombocytopenia of other causes. We divided chronic ITP into four subgroups: presplenectomy, mild (platelet count >30 000 micro (L-1) requiring no therapy), presplenectomy, severe (platelet count <30 000 micro L(-1) requiring therapy but not splenectomy), postsplenectomy, remission (postsplenectomy partial or complete remission without further therapy) and postsplenectomy refractory (required therapy after splenectomy failure). Positive results: total ITP group, 55.4%; presplenectomy, mild, 31.1%; presplenectomy, severe, 42.6%; postsplenectomy, remission, 50.0%; and postsplenectomy, refractory, 87.8%. In addition, the degree of positivity increased with the severity of the patient's disease. The assay had a minimum specificity of 84.4% if clinical factors, consistent with immune thrombocytopenia, were not considered in patients with thrombocytopenia associated with other diseases. However, if clinical factors consistent with immune thrombocytopenia were considered and only patients with questionable immune thrombocytopenia and patients 'lost to follow-up' were included in the false-positive group the specificity was 93.1%. We conclude that the presence of immune thrombocytopenia is highly probable if the immunobead assay is positive and that antigen-specific assays are diagnostically useful in adult chronic ITP.

Effect of a single-dose of olanzapine on sleep in healthy females and males.

The effect of a single dose of 10 mg olanzapine on healthy volunteers of both sexes was examined using polysomnography and power spectral analysis. The structure and continuity of sleep were unaffected by olanzapine in both sexes. The increase in both actual sleep time and slow wave sleep in females correlated with the increase in theta power, while delta power was not significantly elevated, suggesting that theta power may be a sensitive indicator of changes in sleep. The changes in sleep had the same tendency in men, but they were not significant. The difference between the sexes could not be explained by differences in body mass index. Olanzapine affects sleep probably through 5-HT(2C) receptors. The receptor gene is located on the X-chromosome, inducing an allelic difference between the females and males. This difference may contribute to the different effects of olanzapine on sleep. Olanzapine seems to preserve the normal structure of sleep and increase the amount of slow-wave sleep, which might be of additional benefit in treatment of schizophrenia. The effective clinical dose may be lower for females than males.

MDC-L, a novel metalloprotease disintegrin cysteine-rich protein family member expressed by human lymphocytes.

The metalloprotease disintegrin cysteine-rich (MDC) proteins are a recently identified family of transmembrane proteins that function in proteolytic processing of cell surface molecules and in cell adhesion. Since lymphocytes must interact with a constantly changing environment, we hypothesized that lymphocytes would express unique MDC proteins. To identify MDC proteins expressed in human lymph node, a polymerase chain reaction-based strategy combined with degenerate oligonucleotide primers was employed. We report here the identification of MDC-L (ADAM 23), a novel member of the MDC protein family. The results obtained from cDNA cloning and Northern blot analysis of mRNA isolated from various lymphoid tissues indicate that a 2.8-kilobase mRNA encoding a transmembrane form, MDC-Lm, and a 2.2-kilobase mRNA encoding a secreted form, MDC-Ls, are expressed in a tissue-specific manner. MDC-L mRNA was shown to be predominantly expressed in secondary lymphoid tissues, such as lymph node, spleen, small intestine, stomach, colon, appendix, and trachea. Furthermore, immunohistochemical staining with an anti-MDC-L antibody demonstrated that cells with typical lymphocyte morphology are responsible for expression of the MDC-L antigen in these lymphoid tissues. MDC-Lm was found to be expressed on the surface of human peripheral blood lymphocytes and transformed B- and T-lymphocyte cell lines as an 87-kDa protein. Thus, we have identified a novel lymphocyte-expressed MDC protein family member.

Characterization of autoantigenic epitopes on platelet glycoprotein IIb/IIIa using random peptide libraries.

Most patients with chronic immune thrombocytopenic purpura (ITP) have autoantibodies directed against the glycoprotein (GP) IIb/IIIa complex. We have used a filamentous phage library that displays random linear hexapeptides to identify peptide sequences recognized by these autoantibodies. Plasma antibody eluates from two patients were used to select for phage displaying autoantibody-reactive peptides. From patient ITP-1 (known to have two distinct autoantibodies), we identified anti-GPIIb/IIIa antibody-specific phage encoding the peptide sequences Arg-Glu-Lys-Ala-Lys-Trp (REKAKW) and Pro-Val-Val-Trp-Lys-Asn (PVVWKN). Patient ITP-2 bound phage encoding the hexapeptide sequence Arg-Glu-Leu-Leu-Lys-Met. Each phage showed saturable dose-dependent binding to immobilized autoantibody, and binding could be blocked with purified GPIIb/IIIa. Patient ITP-1 autoantibody recognition of phage encoding REKAKW could be blocked with a synthetic peptide derived from the GPIIIa cytoplasmic tail; however, the PVVWKN was not. Using sequential overlapping peptides from the GPIIIa cytoplasmic region, an epitope for ITP-1 was localized to the sequence Arg-Ala-Arg-Ala-Lys-Trp (GPIIIa 734-739). Inhibition studies using synthetic peptides showed that phage REKAKW and PVVWKN were recognized by distinct autoantibodies from patient ITP-1. To determine whether individual patients with ITP possessed autoantibodies that recognize similar antigenic determinants on GPIIb/IIIa, the three phage were tested for binding to five other ITP patient autoantibodies. The phage encoding the peptide PVVWKN was found to bind ITP-1 and one other patient autoantibody. This result suggests that ITP patients recognize a limited number of shared epitopes.

A non-thrombocytopenic bleeding disorder due to an IgG4-kappa anti-GPIIb/IIIa autoantibody.

Autoantibodies in chronic immune thrombocytopenic purpura occasionally interfere with platelet function. We describe a patient with a normal platelet count who had clinically significant mucosal bleeding, a prolonged bleeding time and abnormal platelet aggregation. The patient had high titres of an IgG4 kappa autoantibody, directed to a cation-dependent epitope on platelet glycoprotein IIb/IIIa, which blocked the binding of fibrinogen and fibronectin to this complex. Corticosteroid treatment resulted in clinical improvement and a marked drop in autoantibody concentration. The lack of thrombocytopenia in this patient, despite high autoantibody levels, is best explained by the poor recognition of IgG4 antibodies by phagocytic cells.

Reactivity of autoantibodies from chronic ITP patients with recombinant glycoprotein IIIa peptides.

Chronic immune thrombocytopenia is an autoimmune disorder characterized by destructive thrombocytopenia due to the formation of autoantibodies against platelet-associated antigens. Most antiplatelet autoantibodies react with either the platelet glycoprotein IIb/IIIa or Ib/IX complex, whereas some plasma autoantibodies react with glycoprotein IIIa. Previous studies from our laboratory suggested that most platelet-associated autoantibodies to platelet GPIIb/IIIa, which bind to the intact complex, bind much less avidly to the EDTA-dissociated complex, suggesting that the epitopes were complex-dependent. To evaluate this further we have studied the binding of platelet-associated autoantibody and plasma auto- and alloantibody eluates to large recombinant GPIIIa peptides: peptide 1 (GPIIIa Gly1-Val200); peptide 2 (GPIIIa Arg150-Glu400); peptide 3 (GPIIIa Lys350-Asp550); peptide 4 (GPIIIa Asn450-Val700) and peptide 5 (GPIIIa Trp715-Thr762, cytoplasmic fragment). Of the 33 platelet-associated antibody eluates tested, all bound avidly to the GPIIb/IIIa complex, but only one showed significant binding (>3 SD above control values) to one of the immobilized peptides (peptide 3). Conversely, antibodies known to bind to specific regions of GPIIIa (murine monoclonal antibody, anti-LIBS2; plasma autoantibody against the GPIIIa cytoplasmic fragment and anti-P1A1 antibody) all bound avidly to the GPIIIa peptide containing the appropriate epitope. Based on these and our previous results, we conclude that platelet-associated antibodies from chronic ITP patients rarely bind to epitopes localized to GPIIIa alone.

The effect of therapy on platelet-associated autoantibody in chronic immune thrombocytopenic purpura.

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disorder due to autoantibody-induced destruction of platelets. Several forms of therapy have been used, including corticosteroids, splenectomy, danazol, and a variety of immunosuppressants. We studied the mechanism of action of some of these treatments by evaluating patients' platelet-associated autoantibodies (PAAb) and platelet count before and serially following therapy. Treatment with corticosteroids, splenectomy, cyclophosphamide, and combination chemotherapy resulted in a progressive decrease in PAAb associated with an improvement in the platelet count, and appeared to act by primarily affecting autoantibody production. Conversely, PAAb levels either remained stable or increased during vincristine or danazol therapy despite improvement in the platelet count, suggesting that the major effect of these agents was decreased platelet removal by the reticuloendothelial (RE) system.

Platelet-associated antibody to glycoprotein IIb/IIIa from chronic immune thrombocytopenic purpura patients often binds to divalent cation-dependent antigens.

Chronic immune thrombocytopenic purpura (ITP) is a syndrome of destructive thrombocytopenia due to autoantibodies against platelet-associated antigens. These antigens are most commonly located on the platelet glycoprotein (GP) IIb/IIIa complex. In the present studies, we show that many platelet-associated anti-GPIIb/IIIa autoantibodies from chronic ITP patients depend on conformationally intact GPIIb/IIIa for maximal binding. We studied anti-GPIIb/IIIa autoantibodies from 19 ITP patients (15 platelet-associated, 8 plasma) and alloantibodies from three patients with posttransfusion purpura (anti-PIA1). Antibodies were preincubated with purified intact GPIIb/IIIa, EDTA-dissociated GPIIb/IIIa, GPIIIa, or GPIIb for 2 hours and then residual antibody was measured in an antigen capture assay. The binding results were compared with those obtained using antibody preincubated in buffer. Of the 15 platelet-associated autoantibodies studied, the intact GPIIb/IIIa complex resulted in greater inhibition of antibody binding than the EDTA-dissociated complex, with a mean inhibition ratio (intact/dissociated) of 7.9 (range, 1.4 to 30.3). Little inhibition was noted using either GPIIb or GPIIIa. Conversely, plasma anti-PIA1 alloantibodies or plasma autoantibodies from ITP patients against the c-terminal region of GPIIIa were more efficiently inhibited by the dissociated complex or purified GPIIIa. We conclude that platelet-associated anti-GPIIb/IIIa autoantibodies in chronic ITP are frequently directed to cation-dependent conformational antigens.

Different specificities of platelet-associated and plasma autoantibodies to platelet GPIIb-IIIa in patients with chronic immune thrombocytopenic purpura.

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disorder due to antiplatelet autoantibodies, many of which are directed against platelet membrane glycoprotein (GP) IIb-IIIa or GPIb-IX. In a recent study, we described plasma autoantibodies from 13 selected ITP patients, which required the presence of the putative GPIIIa cytoplasmic region for antibody binding. Since this region may not be available for antibody binding under physiologic conditions, we evaluated the frequency of binding to this or other regions of GPIIb-IIIa by platelet-associated and plasma autoantibody from a group of chronic ITP patients. We studied platelet-associated autoantibodies in 27 patients and plasma antibodies in 21 patients; in 15 patients, both were studied. To determine if autoantibodies were directed to the cytoplasmic portion of GPIIIa or to another portion of the GPIIb-IIIa molecule, antibody eluted from patient platelets or plasma antibody was tested in an antigen capture assay for binding to GPIIb-IIIa obtained from Chinese hamster ovary (CHO) cells transfected with GPIIb and either intact GPIIIa or GPIIIa lacking the carboxy terminal 35 residues. Of the 21 plasma autoantibodies tested, 13 bound primarily to the carboxy terminus of GPIIIa and eight to other epitopes. Conversely, all 26 platelet-associated autoantibodies, including eight of the 13 with anti-carboxy terminus antibodies, bound to epitopes in other regions of GPIIb-IIIa. Comparison of the degree of antibody adsorption by intact or lysed platelets indicated that epitopes on the c-terminal region of GPIIIa are relatively inaccessible on the surface of intact washed platelets when compared with other epitopes. We conclude that the importance of plasma autoantibodies in chronic ITP patients should be interpreted cautiously, since their specificity may differ from that of antibodies bound to the platelet. Whether antibodies against the c-terminus of GPIIIa are of pathogenetic importance remains to be determined, although patients with these antibodies have particularly severe disease.

Localization of a PlA1 epitope to the amino terminal 66 residues of platelet glycoprotein IIIa.

A platelet glycoprotein (GP) IIIa epitope library was constructed by insertion of randomly cleaved GPIIIa cDNA fragments in the prokaryotic expression vector lambda gt22 and screened with purified anti-PlA1 antibodies for clones expressing a PlA1 epitope. Five independent clones were isolated and characterized by nucleotide sequencing. The smallest anti-PlA1 reactive clone obtained encoded the amino terminal 66 residues of mature GPIIIa. Substitution of leucine33 (PlA1) with a proline33 (PlA2) by in vitro mutagenesis resulted in the loss of anti-PlA1 reactivity; however, this clone still reacted with anti-GPIIIa polyclonal antibodies. These data indicate that a PlA1 alloantigenic epitope is located within a small, unglycosylated fragment of GPIIIa containing the polymorphism responsible for the PIA phenotype. Furthermore, these results prove that small recombinant mimics of a PlA1 epitope may be synthesized and used for detection of these alloantibodies.

Autoantibodies to the presumptive cytoplasmic domain of platelet glycoprotein IIIa in patients with chronic immune thrombocytopenic purpura.

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disorder due to autoantibodies against platelets that result in their destruction. In some patients, these autoantibodies bind to platelet glycoprotein (GP) IIIa. With the aim of better defining the antigenic epitopes, plasma from 13 selected patients with chronic ITP known to have anti-GPIIb/IIIa autoantibodies was tested for reactivity with nine synthetic peptides corresponding to different regions of the GP IIIa molecule. Of these plasmas, five bound significantly (P less than .001) with either peptide 8 (amino acids 721-744) or peptide 9 (amino acids 742-762), which together form most of the carboxyterminal region presumed to be the cytoplasmic domain. Three of these positive plasmas, were tested further. In two of these positive plasmas, the anti-peptide antibodies represented greater than 80% of the detectable circulating autoantibody. To further evaluate the importance of the carboxyterminal region as an antigenic site, the chronic ITP plasmas were tested against Chinese hamster ovary cells transfected with GPIIb and either whole GPIIIa or GPIIIa lacking amino acids 728 to 762. Ten of the 13 plasmas required the presence of this region for significant autoantibody binding. We conclude that the carboxyterminal region is an important area for stimulating antiplatelet autoantibody formation in some patients with chronic ITP. It is not known whether these autoantibodies to the presumed cytoplasmic domain play an important role in the pathogenesis of the disease or occur as a secondary phenomenon during the course of platelet destruction.

Different forms of chronic childhood thrombocytopenic purpura defined by antiplatelet autoantibodies.

To determine whether detection of antiplatelet autoantibodies (AAb) to glycoproteins IIb/IIIa and Ib/IX may be useful in defining different forms of chronic thrombocytopenic purpura (TP) in children, we analyzed for AAb the platelet and plasma samples from 36 children with chronic TP (mean duration 4.4 years), from 31 children with normal platelet counts at the time of blood sampling but with chronic TP in the past (mean duration 2.9 years), and from 23 adults with chronic TP; the results were correlated with the clinical data. Antiplatelet autoantibodies were detected in 26 (72.2%) of 36 children with ongoing TP, 15 (48.4%) of 31 children with TP in the past, and 12 (66.7%) of 18 adults with TP. All children with high AAb ratios (greater than 5 times the control mean + 3 SD) were more than 8 years of age at diagnosis (mean age 12.4 years compared with 7.1 years in children with moderate or negative AAb levels; p = 0.003). The results suggest that the outcome for adolescents with high platelet-associated AAb levels may be similar to that of adults, whereas younger children may have a greater chance of spontaneous remission. The children with chronic TP in the past and elevated platelet-associated AAb levels may have a "compensated" TP and therefore may be at risk for relapses. Future studies aimed at serial AAb determination throughout the patients' courses may further define TP subgroups.

Inhibition of autoantibody binding to platelet glycoprotein IIb/IIIa by anti-idiotypic antibodies in intravenous gammaglobulin.

Intravenous immunoglobulin (IVIgG) causes an acute rise in the platelet count in the majority of patients with chronic immune thrombocytopenic purpura (ITP) but the mechanism(s) of action is still unknown. We evaluated the ability of three different IVIgG preparations to inhibit the in vitro binding of autoantibody to platelet glycoprotein (GP) IIb/IIIa. ITP plasma, known to contain anti-GPIIb/IIIa antibodies, was incubated overnight with either IVIgG or bovine serum albumin (BSA) followed by measurement of the autoantibody titer. Binding of autoantibody from eight ITP patients was inhibited by IVIgG in proportion to the IVIgG concentration. Using 3.2% IVIgG, compatible with therapeutic concentrations expected in vivo, mean inhibition of autoantibody binding ranged from 20.2% to 41.3%. No inhibition by IVIgG of alloantibody binding to the same or different molecules was detected (five patients with anti-GPIIb/IIIa and two with anti-HLA alloantibodies). F(ab')2 fragments of IVIgG also inhibited the binding of both plasma autoantibodies and purified anti-GPIIb/IIIA autoantibodies prepared by elution from antigen affinity columns. A portion of the anti-idiotypic antibodies could be adsorbed from IVIgG using insolubilized, purified anti-GPIIb/IIIa autoantibody. These results show that IVIgG preparations from normal donors contain anti-idiotypic antibodies directed against idiotypes located on GPIIb/IIIa autoantibodies but do not have anti-idiotypes to platelet alloantibodies against the same or different molecules. The importance of these anti-idiotypic antibodies in the therapeutic response to IVIgG remains to be established.

Autoantibodies to platelet glycoproteins in patients with disease-related immune thrombocytopenia.

Although increased platelet destruction and elevated platelet-associated IgG have been shown in patients with lymphomas and various autoimmune diseases, such as systemic lupus erythematosus (SLE), there have been few studies evaluating autoantibodies against platelet-specific antigens. We evaluated 24 patients retrospectively with disease-related thrombocytopenia (12 with lymphoproliferative diseases and 12 with various autoimmune disorders) using a recently reported antigen-specific assay. Autoantibodies against platelet GPIIb/IIIa or GPIb/IX were noted in 15 of the 24 patients (10 of 12 with autoimmune disease and five of 12 with lymphoproliferative disorders). Platelet-associated autoantibodies were present in 60% and plasma autoantibodies in 33%. Anti-GPIIb/IIIa autoantibodies were much more common than those against GPIb/IX. In one patient each with thrombocytopenia and either SLE or myasthenia gravis, absorption of plasma with platelets completely removed the anti-GPIIb/IIIa autoantibodies, but did not affect the level of anti-cochlear autoantibody involved with immune-mediated hearing loss in the SLE patient or the anti-acetylcholine receptor autoantibody in the myasthenic patient. These findings show that, in some cases of disease-related immune thrombocytopenia, autoantibodies against GPIIb/IIIa or GPIb/IX can be detected similar to those seen in chronic ITP. As shown in two patients with multiple autoimmune manifestations, the various autoantibodies have diverse specificities and do not crossreact.

Autoantibodies against platelet membrane glycoproteins in children with acute and chronic immune thrombocytopenic purpura.

The autoimmune nature of chronic immune thrombocytopenic purpura (ITP) in adults is widely accepted. In contrast, the pathogenetic mechanism in acute and chronic ITP in children is not known. In this report, we studied 39 children with destructive thrombocytopenia, 15 patients with acute ITP and 24 patients with chronic ITP. Platelet autoantibodies to platelet glycoprotein IIb/IIIa were detected in 14 of 24 patients (58.3%) in the chronic ITP group and in four of 15 (26.7%) with acute ITP. Binding ratios (+/- SD) of positive patients were significantly greater (P = .01) in chronic ITP (8.0 +/- 9.1) when compared with those of acute ITP where the binding ratios were only slightly above the normal range (1.9 +/- 0.4). The results show that autoantibodies against platelet glycoproteins are present in the majority of children with chronic ITP confirming the autoimmune nature of this disorder. The minimal elevation seen in the positive children with acute ITP suggests a different pathogenetic mechanism. These data suggest that this approach may be useful in differentiating acute from chronic ITP patients.

Autoantibodies in chronic ITP.

Chronic ITP is a syndrome of destructive thrombocytopenia due in most cases to antiplatelet autoantibodies. In the present studies we have studied 74 patients with chronic ITP using a new immunobead assay. Of these, 59 (79.7%) had demonstrable platelet-associated autoantibodies: 48 against platelet glycoprotein IIb/IIIa and 11 against glycoprotein Ib/IX. Plasma autoantibodies were studied in all patients and 32 (43.2%) had positive results; in each case the patient also had platelet-associated autoantibodies directed to the same antigen. We conclude that the majority of patients with chronic ITP have autoantibodies against platelet membrane glycoproteins and that the immunobead assay is a sensitive and reproducible method for their detection which is applicable to the routine hospital laboratory.