Immunodiagnosis and immunotherapy in autistic children

Immune Dysfunction and Autoimmunity as Pathological Mechanisms in Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a group of heterogeneous neurological disorders that are highly variable and are clinically characterized by deficits in social interactions, communication, and stereotypical behaviors. Prevalence has risen from 1 in 10,000 in 1972 to 1 in 59 children in the United States in 2014. This rise in prevalence could be due in part to better diagnoses and awareness, however, these together cannot solely account for such a significant rise. While causative connections have not been proven in the majority of cases, many current studies focus on the combined effects of genetics and environment. Strikingly, a distinct picture of immune dysfunction has emerged and been supported by many independent studies over the past decade. Many players in the immune-ASD puzzle may be mechanistically contributing to pathogenesis of these disorders, including skewed cytokine responses, differences in total numbers and frequencies of immune cells and their subsets, neuroinflammation, and adaptive and innate immune dysfunction, as well as altered levels of immunoglobulin and the presence of autoantibodies which have been found in a substantial number of individuals with ASD. This review summarizes the latest research linking ASD, autoimmunity and immune dysfunction, and discusses evidence of a potential autoimmune component of ASD.

Evaluation of antibodies to cytomegalovirus and Epstein-Barr virus in patients with autism spectrum disorder

Autism is a neurodevelopmental disease that manifested by a wide range of behavioral disorders. Although the etiology of autism is remained unknown but it is suggested that ASD have a complex etiology, including genetic and environmental factors, which may explain the observed different behavioral disorders in these patients. One of the proposed reasons for autism is viral infection in the early stages of development. The mechanism by which viral infection could lead to autism is still unclear.Previous studiesemphasized on the role of family membersof Herpesviruses in autism susceptibility. In this study, anti-Cytomegalovirus (CMV) and anti-Epstein-Barr virus (EBV) antibodies in the serum of 45 children with autism and 45 healthy individuals were evaluated. Serum samples were isolated from 5 ml blood of the patients and controls. Sandwich ELISA was used to quantitatively measure antibodies against the mentioned viruses. Results analyzed by SPSS software showed an increased amount of anti-CMV IgG and IgM antibodies in the blood of patients with Autism but not statistically significant (P< 0.05). The anti-EBV IgM antibody in the blood of patients with Autism was not only increased but also statistically significant (P< 0.05), however, the IgG level against EBV in the serum of ASD patients showed no significant difference in comparison to healthy controls. So it can be said that although the mechanisms of viral infection in autism is unknown, but probably EBV infection is associated with an increased risk of autism.

Immunization and children at risk for autism

Possible connections between immunization and developmental disorders, most notably autistic disorders, have been the subject of a great deal of debate and have caused much concern for parents who want to make the safest choices for their children. Anxiety has risen steadily since the mid-1990s, when a medical investigative team led by A Wakefield postulated that the measles-mumps-rubella (MMR) vaccine may be a causative factor in the development of autism spectrum disorder. Since this initial publication, immunization remains controversial for some parents and the uptake of the MMR vaccine has fallen in some countries, despite much discussion regarding the safety of MMR, a lack of evidence for an association between MMR and autism, and the risks of insufficient protection against wild measles virus infection. The Canadian uptake of MMR in 1998 was 95%, but data do not exist to document any change in Canada since that time. Many clinicians are concerned that the uptake in younger siblings of children with autism is considerably lower.Further anxiety for parents has been caused by the suggested association between developmental disorders and mercury toxicity due to thimerosal, which is used as a preservative in some vaccines. Many Canadian parents, while continuing to seek chelation therapy in response to this suggestion, are not aware that, in Canada, thimerosal has never been added to MMR, and has not been present in diphtheria-pertussis-tetanus-poliomyelitis or pentavalent vaccines since 1992. It is found in only Hepatitis B vaccine in some provinces.The present article is intended to be a guide for physicians as they counsel parents.

The neuropathology of autism: where do we stand?

The neurobiology and neuropathology of the autism spectrum disorders (ASD) remain poorly defined. Brain imaging studies suggest that the deficits in social cognition, language, communication and stereotypical patterns of behaviour that are manifest in individuals with ASD, are related to functional disturbance and 'disconnectivity', affecting multiple brain regions. These impairments are considered to arise as a consequence of abnormal pre- and postnatal development of a distributed neural network. Examination of the brain post mortem continues to provide fundamental information concerning the cellular and subcellular alterations that take place in the brain of autistic individuals. Neuropathological observations that have emerged over the past decade also point towards early pre- and postnatal developmental abnormalities that involve multiple regions of the brain, including the cerebral cortex, cortical white matter, amygdala, brainstem and cerebellum. However, the neuropathology of autism is yet to be clearly defined, and there are several areas that remain open to further investigation. In this respect, more concerted efforts are required to examine the various aspects of cellular pathology affecting the brain in autism. This paper briefly highlights four key areas that warrant further evaluation.

Brain-derived neurotrophic factor and autoantibodies to neural antigens in sera of children with autistic spectrum disorders, Landau-Kleffner syndrome, and epilepsy

BACKGROUND

Brain derived neurotrophic factor (BDNF) elevation in newborn sera predicts intellectual/social developmental abnormalities. Other autoantibodies (AAs) to endothelial cells (ECs) and myelin basic protein (MBP) are also elevated in some children. We tested relationships between BDNF, BDNF AAs, and other AAs in children with these disorders.

METHODS

BDNF levels and IgG/IgM autoantibodies to BDNF, ECs, MBP, and histones were measured in children with autism, childhood disintegrative disorder (CDD), pervasive developmental delay-not otherwise specified (PDD-nos), acquired epilepsy, Landau-Kleffner syndrome (LKS); healthy children (HC), and children with non-neurological illnesses (NNI).

RESULTS

Mean BDNF levels were elevated in children with autism and CDD, (p < or = 0.0002) compared to HC or NNI. Mean IgG and IgM BDNF AAs were elevated in children with autism, CDD and epilepsy (p < or = 0.0005) compared to HC but not to NNI. Mean IgM AA EC titers detected by immunocytochemistry were higher in autism, PDD-NOS, epilepsy, and LKS (p < or = 0.005) compared to HC and NNI. While mean ELISA IgG EC AAs were higher in autism and PPD-NOS (p < 0.005) compared to HC but not NNI, ELISA IgM EC AAs were higher in children with autism, CDD, PDD-NOS, and epilepsy compared to both HC and NNI (p < 0.0005). Mean anti-MBP IgG and IgM titers were higher in all study groups (p < 0.005) except for LKS compared to both HC and NNI.

CONCLUSION

Children with developmental disorders and epilepsy have higher AAs to several neural antigens compared to controls. The presence of both BDNF AAs and elevated BDNF levels in some children with autism and CDD suggests a previously unrecognized interaction between the immune system and BDNF.

Immune function in autistic children

BACKGROUND

There have been reports that some children with autistic spectrum disorders have abnormal immune function. However, data in this area remain scarce and conflicting.

OBJECTIVE

To evaluate the immune function of a series of autistic children in the context of this proposed association.

METHODS

We prospectively collected data on 24 autistic children who, between January 1, 1996, and September 30, 1998, were referred unsolicited to an immunology clinic. We examined the clinical history and evaluated immunoglobulin levels; specific antibody titers to diphtheria, tetanus, and Haemophilus influenzae; T- + B-cell numbers; T-cell proliferation; and complement studies.

RESULTS

Seven of the 24 children had a history of recurrent infections. Only 2 patients had immunoglobulin levels that were outside the age-adjusted reference ranges, 1 of whom was subsequently diagnosed as having common variable immune deficiency. All the patients had normal in vitro T-cell function and complement study results, and only 2 of 24 patients had subtle derangements in T-cell numbers. Elevated levels of IgE were found in 5 patients, which correlated with a clinical history of atopy. Low diphtheria or tetanus antibody levels were found in 12 patients, but in 11 of these, vaccination status was not up-to-date.

CONCLUSIONS

Most of the autistic children studied had normal immune function, suggesting that routine immunologic investigation is unlikely to be of benefit in most autistic children and should be considered only when there is a history suggestive of recurrent infections.

Immunological aetiology of major psychiatric disorders: evidence and therapeutic implications

Historically, immunological research in psychiatry was based on empirical findings and early epidemiological studies indicating a possible relationship between psychiatric symptoms and acute infectious diseases. However, aetiopathological explanations for psychiatric disorders are no longer closely related to acute infection. Nevertheless, immune hypotheses have been discussed in schizophrenia, affective disorders and infantile autism in the last decades. Although the variability between the results of the epidemiological studies conducted to date is strikingly high, there is still some evidence that the immune system might play a role in the aetiopathogenesis of these three psychiatric diseases, at least in subgroups of patients. In anxiety disorders immunological research is still very much in its infancy, and the few and inconsistent data of immune changes in these patients are believed to reflect the influence of short- or long-term stress exposure. Nevertheless, there are also some hints raising the possibility that autoimmune mechanisms could interrupt neurotransmission, which would be of significance in certain patients with anxiety and panic disorders. Drug and alcohol (ethanol) dependence are not believed to be primarily influenced by an immunological aetiology. On the other hand, immune reactions due to different drugs of abuse and alcohol may directly or indirectly influence the course of concomitant somatic diseases. In different organic brain disorders the underlying somatic disease is defined as a primary immune or autoimmune disorder, for instance HIV infection or systemic lupus erythematosus (SLE). For other neurodegenerative disorders, such as Alzheimer's disease, immunoaetiopathological mechanisms are supported by experimental and clinical studies. Treatment strategies based on immune mechanisms have been investigated in patients with schizophrenia and affective disorders. Furthermore, some antipsychotics and most antidepressants are known to have direct or indirect effects on the immune system. Different immunotherapies have been used in autism, including transfer factor, pentoxifylline, intravenous immunoglobulins and corticosteroids. Immunosuppressive and/or immunomodulating agents are well established methods for treating the neuropsychiatric sequelae of immune or autoimmune disorders, for example AIDS and SLE. Therapeutic approaches in Alzheimer's disease also apply immunological methods such as strategies of active/passive immunisation and NSAIDs. Considering the comprehensive interactive network between mind and body, future research should focus on approaches linking targets of the different involved systems.

Neurologic treatment strategies in autism: an overview of medical intervention strategies

Child neurologists are likely to be caring for an increasing number of patients with autistic spectrum disorder (ASD). ASD may occur in as many as 1/100 to 1/200 births. It appears to be a multifactorial disease, with many phenotypes or subgroups. No simple treatment is currently approved for curing or managing core symptoms of autism. We rationally propose a symptom-based review of what treatments may offer relief to specific subtypes of clinical behaviors seen in autism. There is a lack of clinically based evidence on which to universally recommend a rational clinical algorithm for treatment; we suggest that rational pharmacotherapy may offer symptomatic relief to core areas of dysfunction in the autistic population. Future research into rational medical treatment options is desperately needed.

Intestinal cytokines in children with pervasive developmental disorders

OBJECTIVES

A relationship between autism and gastrointestinal (GI) immune dysregulation has been postulated based on incidence of GI complaints as well as macroscopically observed lymphonodular hyperplasia and microscopically determined enterocolitis in pediatric patients with autism. To evaluate GI immunity, we quantitatively assessed levels of proinflammatory cytokines, interleukin (IL)-6, IL-8, and IL-1beta, produced by intestinal biopsies of children with pervasive developmental disorders.

METHODS

Fifteen patients, six with pervasive developmental disorders and nine age-matched controls, presenting for diagnostic colonoscopy were enrolled. Endoscopic biopsies were organ cultured, supernatants were harvested, and IL-6, IL-8, and IL-1beta levels were quantified by ELISA. Tissue histology was evaluated by blinded pathologists.

RESULTS

Concentrations of IL-6 from intestinal organ culture supernatants of patients with pervasive developmental disorders (median 318.5 pg/ml, interquartile range 282.0-393.0 pg/ml) when compared with controls (median 436.9 pg/ml, interquartile range 312.6-602.5 pg/ml) were not significantly different (p = 0.0987). Concentrations of IL-8 (median 84,000 pg/ml, interquartile range 16,000-143,000 pg/ml) when compared with controls (median 177,000 pg/ml, interquartile range 114,000-244,000 pg/ml) were not significantly different (p = 0.0707). Concentrations of IL-1beta (median 0.0 pg/ml, interquartile range 0.0-94.7 pg/ml) when compared with controls (median 0.0 pg/ml, interquartile range 0.0-60.2 pg/ml) were not significantly different (p = 0.8826). Tissue histology was nonpathological for all patients.

CONCLUSIONS

We have demonstrated no significant difference in production of IL-6, IL-8, and IL-1beta between patients with pervasive developmental disorders and age-matched controls. In general, intestinal levels of IL-6 and IL-8 were lower in patients with pervasive developmental disorders than in age-matched controls. These data fail to support an association between autism and GI inflammation.

Childhood autism: a circuit syndrome?

BACKGROUND

Autism is a disorder that can lead to life-long disability. Currently, the etiology of autism is unknown, and although there are treatments for some of the behavioral abnormalities, there is no cure.

REVIEW SUMMARY

While this article will review the clinical, anatomic, and pathologic features seen in autism, the primary focus will be to present a new and provocative unifying theory regarding the underlying mechanisms causing this disorder. Current research advances, some controversial, will be discussed, and a novel definition of autism as a "circuit syndrome" will be presented. The work elaborated here will tie many of the disparate findings together, based on the idea that autism arises from abnormalities of the cerebellolimbic circuitry. Some of the more alternative theories of autism, such as mercury toxicity, linkage to the measles, mumps, and rubella vaccine, and the use of secretin will be discussed. Finally, pharmacologic treatment options will be reviewed.

CONCLUSIONS

Autism is not single disorder but represents dysfunction of the cerebellolimbic circuitry that can arise from many different etiologies.

Pathophysiology of autism: current opinions

Research on the neurochemical aspects of the pathophysiology of autism is still increasing and publications are abundant. In this paper we reviewed significant data from the last decade and recent research results from our center. We focused on molecules influencing the central nervous system (CNS) and consecutively responsible for typical autistic behavior. We highlighted the mutual relationship between the serotonergic, immunological and endocrinological system and the interaction of these three pivotal systems with predisposing (genetic)and external (pre-, peri- and postnatal) conditions and xenobiotics. We stressed the influence of age, pubertal stage, sex, race and IQ on biological data. There is growing evidence that the complexity and variability of those interactions might be responsible for the heterogeneity of behavioral phenotypes and biological findings in Autism. Genetic, neuroanatomical and neurophysiological data were mentioned according their relevance to neurochemical opinions.

Intra-monocyte pathogens delineate autism subgroups

Immune panels of many autism-spectrum children reveal signs of atypical infections and shifted cell counts. In conjunction with trait-related cerebral hypometabolism and hypoperfusion, these findings suggest a hypothesis: Several autism-spectrum subgroups derive from intra-monocyte pathogens such as measles virus, cytomegalovirus, human herpesvirus 6, and Yersinia enterocolitica. Furthermore, with much inter-child variation, their effects manifest as diminished hematopoiesis, impaired peripheral immunity, and altered blood-brain barrier function often accompanied by demyelination. In some such children, one or more of these pathogens persists as a chronic-active, seemingly subclinical infection etiologically significant to the child's autistic traits. Within these subgroups, immune impairments and atypical infections may be treatable.

Effectiveness of N,N-dimethylglycine in autism and pervasive developmental disorder

N,N-dimethylglycine, a dietary supplement, has been reported to be beneficial in children with autism and pervasive developmental disorder. We examined the effectiveness of dimethylglycine in children with autism and pervasive developmental disorder in a double-blind, placebo-controlled study. Thirty-seven children between 3 and 11 years of age with a diagnosis of autism and/or pervasive developmental disorder were gender and age matched and randomly assigned to receive either placebo or dimethylglycine for 4 weeks. All children were assessed before and after treatment on two behavioral measures, the Vineland Maladaptive Behavior Domain and the Aberrant Behavior Checklist. Standardized neurologic examinations before and after treatment on 33 children showed no change. An overall improvement on all behavioral measures was observed for both the placebo and the dimethylglycine groups. However, the improvement among the children who received dimethylglycine was not statistically different from the improvement observed among the children who received the placebo. The children who participated in this study were a heterogeneous group, and their apparent responses to the dimethylglycine varied. Some children appeared to respond positively to the dimethylglycine, and there was a smaller proportion of negative changes in the dimethylglycine group, but the quantitative changes in the dimethylglycine behavioral assessments were not significantly different from what was observed among children who received placebo.

Serum autoantibodies to brain in Landau-Kleffner variant, autism, and other neurologic disorders

OBJECTIVE

Etiologically unexplained disorders of language and social development have often been reported to improve in patients treated with immune-modulating regimens. Here we determined the frequency of autoantibodies to brain among such children.

DESIGN

We collected sera from a cohort of children with (1) pure Landau-Kleffner syndrome (n = 2), (2) Landau-Kleffner syndrome variant (LKSV, n = 11), and (3) autistic spectrum disorder (ASD, n = 11). None had received immune-modulating treatment before the serum sample was obtained. Control sera (n = 71) were from 29 healthy children, 22 with non-neurologic illnesses (NNIs), and 20 children with other neurologic disorders (ONDs). We identified brain autoantibodies by immunostaining of human temporal cortex and antinuclear autoantibodies using commercially available kits.

RESULTS

IgG anti-brain autoantibodies were present in 45% of sera from children with LKSV, 27% with ASD, and 10% with ONDs compared with 2% from healthy children and control children with NNIs. IgM autoantibodies were present in 36% of sera from children with ASD, 9% with LKSV, and 15% with ONDs compared with 0% of control sera. Labeling studies identified one antigenic target to be endothelial cells. Antinuclear antibodies with titers >/=1:80 were more common in children with ASD and control children with ONDs.

CONCLUSION

Children with LKSV and ASD have a greater frequency of serum antibodies to brain endothelial cells and to nuclei than children with NNIs or healthy children. The presence of these antibodies raises the possibility that autoimmunity plays a role in the pathogenesis of language and social developmental abnormalities in a subset of children with these disorders.

Serological association of measles virus and human herpesvirus-6 with brain autoantibodies in autism

Considering an autoimmunity and autism connection, brain autoantibodies to myelin basic protein (anti-MBP) and neuron-axon filament protein (anti-NAFP) have been found in autistic children. In this current study, we examined associations between virus serology and autoantibody by simultaneous analysis of measles virus antibody (measles-IgG), human herpesvirus-6 antibody (HHV-6-IgG), anti-MBP, and anti-NAFP. We found that measles-IgG and HHV-6-IgG titers were moderately higher in autistic children but they did not significantly differ from normal controls. Moreover, we found that a vast majority of virus serology-positive autistic sera was also positive for brain autoantibody: (i) 90% of measles-IgG-positive autistic sera was also positive for anti-MBP; (ii) 73% of measles-IgG-positive autistic sera was also positive for anti-NAFP; (iii) 84% of HHV-6-IgG-positive autistic sera was also positive for anti-MBP; and (iv) 72% of HHV-6-IgG-positive autistic sera was also positive for anti-NAFP. This study is the first to report an association between virus serology and brain autoantibody in autism; it supports the hypothesis that a virus-induced autoimmune response may play a causal role in autism.

Circulating autoantibodies to neuronal and glial filament proteins in autism

Autoimmunity may be a pathogenic factor in autism, a behavioral disorder of early childhood onset. Circulating autoantibodies are produced in organ-specific autoimmunity; therefore, we investigated them in the plasma of autistic subjects, mentally retarded (MR) subjects, and healthy controls. Autoantibodies (IgG isotype) to neuron-axon filament protein (anti-NAFP) and glial fibrillary acidic protein (anti-GFAP) were analyzed by the Western immunoblotting technique. We found a significant increase in incidence of anti-NAFP (P = .004) and anti-GFAP (P = .002) in autistic subjects, but not in MR subjects. Clinically, these autoantibodies may be related to autoimmune pathology in autism.

Autism and the immune system

As our knowledge of the interactions of the immune, nervous and endocrine systems progresses, complex links with the origin and course of psychopathology in childhood are revealed. In this article the neuroimmunological literature on autism is reviewed. Relevant aspects of immune functioning and the neuroendocrine-immune network are described. We present the immunological findings in autistic patients within two related conceptual frameworks: a viral and an autoimmune hypothesis. Interpretation of data is hampered by conceptual and methodological differences between studies. Both the clinical significance of the immune changes and the causal connection between immune changes and psychopathological phenomena in autism remain to be elucidated. Recommendations for further research are given.

Plasma increase of interleukin-12 and interferon-gamma. Pathological significance in autism

Immune factors such as autoimmunity have been implicated in the genesis of autism, a neurodevelopmental disorder. Since autoimmune response involves immune activation, the plasma levels of interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), interleukin-12 (IL-12), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and soluble intercellular adhesion molecule-1 (sICAM-1) were measured in autistic patients and age-matched normal controls. The levels of IL-12 and IFN-gamma were significantly (P < or = 0.05) higher in patients as compared to controls. However, IFN-alpha, IL-6, TNF-alpha, and sICAM-1 levels did not significantly differ between the two groups. Because macrophage-derived IL-12 is known to selectively induce IFN-gamma in T helper type-1 (Th-1) cells, it is suggested that IL-12 and IFN-gamma increases may indicate antigenic stimulation of Th-1 cells pathogenetically linked to autoimmunity in autism.

Dialysable lymphocyte extract (DLyE) in infantile onset autism: a pilot study

40 infantile autistic patients were studied. They ranged from 6 years to 15 years of age at entry. 22 were cases of classical infantile autism; whereas 18 lacked one or more clinical defects associated with infantile autism ("pseudo-autism"). Of the 22 with classic autism, 21 responded to transfer factor (TF) treatment by gaining at least 2 points in symptoms severity score average (SSSA); and 10 became normal in that they were main-streamed in school and clinical characteristics were fully normalized. Of the 18 remaining, 4 responded to TF, some to other therapies. After cessation of TF therapy, 5 in the autistic group and 3 of the pseudo-autistic group regressed, but they did not drop as low as baseline levels.

Receptor inhibition by immunoglobulins: specific inhibition by autistic children, their relatives, and control subjects

Forty-two parents of children with autistic disorder, 15 children with autistic disorder, 17 siblings of children with autistic disorder, and 12 unrelated normal adult controls were studied to determine if immunoglobulins isolated from their plasma would inhibit binding of the 5HT1A agonist, [3H]-8-hydroxy-N,N-dipropyl-2-aminotetralin (DPAT) to 5HT1A receptors in human hippocampal membranes. There were no significant differences among the means of percentage inhibition of DPAT binding of parents, children with autistic disorder, siblings, or unrelated controls. In addition, there were no differences in the proportion of subjects with > 15% DPAT inhibition among autistic children, their parents, their siblings, or unrelated controls. Immunoglobulin inhibition was not specific for the 5HT1A receptor binding site, since immunoglobulins inhibited binding to 5HT2, D1, D2, and alpha 2-adrenergic binding sites. The immunoglobulins isolated from normal controls inhibited [3H]-rauwolscine binding at alpha 2-adrenergic sites less than immunoglobulins of children with autistic disorder and their parents and siblings. This study did not support the hypothesis that autoantibodies to 5HT1A or 5HT2 receptors are characteristic of autistic disorder.

Changes of soluble interleukin-2, interleukin-2 receptor, T8 antigen, and interleukin-1 in the serum of autistic children

Immune abnormalities in autistic children led us to study for indirect evidence of immune activation as measured by the serum analysis of soluble interleukin-2 (sIL-2), interleukin-2 receptor (sIL-2R), T8 antigen (sT8), and interleukin-1 (sIL-1). The serum concentration of these soluble antigens was quantitated by enzyme-linked immunosorbent assays. The concentration of sIL-2 and sT8, but not of sIL-2R and sIL-1, antigens was significantly (P less than 0.05) increased in the sera of autistic children over that in the control healthy children or children with mental retardation (non-Down's syndrome). This finding indirectly indicates that the activation of a subpopulation of T cells occurs in some children with autism.

CD4+ helper T cell depression in autism

CD4+ (helper) T cells are a heterogenous population of lymphocytes including at least two distinct subpopulations. To investigate the possibility that immune abnormalities in some subjects with autism may involve abnormal distributions of CD4+ and/or CD8+ cells, (suppressor) T cells, peripheral blood lymphocytes of 25 autistic subjects were characterized with monoclonal antibodies and flow cytometry. The autistic subjects had a significantly lower percentage and number of CD4+ cells, a lower number of T cells (CD2+ cells) and B cells (CD20+ cells), and a lower percentage and number of total lymphocytes than siblings and normal subjects. The level of blood values for female subjects appeared lower than those for males as compared to normal subjects of the same sex. These results suggest that a decrease in CD4+ cells is associated with autism.

Deficiency of suppressor-inducer (CD4+CD45RA+) T cells in autism

CD4+ cells are a heterogenous population of lymphocytes including at least two distinct subpopulations: CD45RA+ cells, inducers of suppressor T cells and CDw29+ cells, inducers of helper function for antibody production. To investigate the possibility that immune abnormalities in autism may involve abnormal distribution of these helper subpopulations, monoclonal antibodies were used in flow cytometric analysis to characterize peripheral blood lymphocytes of 36 subjects with autism. The autistic subjects as compared to a group of 35 healthy age-matched subjects had a significantly reduced number of lymphocytes, a decreased number of CD2+ T cells and reduced numbers of CD4+ and CD4+CD45RA+ lymphocytes. The numbers of B (CD20+) cells, suppressor T (CD8+) cells, inducers of helper function (CD4+CDw29+) and natural killer (CD56+) cells were not altered in the autistic subjects. Our results suggest that an alteration in the suppressor-inducer T-cell subset is associated with autism.

Autism: review of neurochemical investigation

The neurochemistry of autism, the most well-validated childhood neuropsychiatric disorder, has been studied extensively over the past three decades. Autism is of interest neurochemically because it represents a relatively homogeneous disorder with a triad of social, communicative, and intellectual developmental disturbance. Because a sufficient animal model has been lacking and relatively few diagnosed people with autism have died, most investigation has been of peripheral fluids and tissues. The most consistent finding has been that over 25% of autistic children and adolescents are hyperserotonemic. However, after 29 years of investigation, the mechanism of hyperserotonemia has not been determined. Hyperserotonemia has been found to be familial. Elevated plasma norepinephrine has also been a replicated finding. Cerebrospinal fluid (CSF) opiate activity has been found to be elevated in two studies. Plasma cyclic adenosine monophosphate (cAMP) has been found to be elevated in autistic children. A high rate of nonsuppression after dexamethasone and blunted or delayed growth hormone response to L-dopa have been found. Abnormal cell-mediated immunity has been replicated consistently in autism. Although several pharmacological trials have been conducted and shown promise in initial open trials, only "typical" antipsychotic drugs have shown replicable chronic ameliorating effects in double-blind trials. However, chronic neurotoxicity (tardive dyskinesia) has also been revealed. Findings of morphological changes in the cerebellum have been replicated. Findings in need of replication include diminished platelet function, increased baseline CSF homovanillic acid, decreased nerve cell adhesion molecule serum fragment, blunted prolactin response to fenfluramine, amelioration of symptoms by naltrexone and bromocriptine, reduced electroretinographic (ERG) b-wave amplitude, and morphological changes in the hippocampus, amygdala, and septal nuclei. In addition to refining and replicating past findings, future directions that may be fruitful include investigation of neurochemical aspects of platelet function, of interactions between monoaminergic systems, of phosphatidylinositides, and of pharmacological response to "atypical" antipsychotic agents and relatively selective serotonin receptor subtype agonists or antagonists.