Diagnostic relevance of IgE sensitization profiles to eight recombinant Phleum pratense molecules

BACKGROUND

Grass pollen-related seasonal allergic rhinoconjunctivitis (SARg) is clinically heterogeneous in severity, comorbidities, and response to treatment. The component-resolved diagnostics disclosed also a high heterogeneity at molecular level. Our study aimed at analyzing the characteristics of the IgE sensitization to Phleum pratense molecules and investigating the diagnostic relevance of such molecules in childhood.

METHODS

We examined 1120 children (age 4-18 years) with SARg. Standardized questionnaires on atopy were acquired through informatics platform (AllergyCARD™). Skin prick tests were performed with pollen extracts. Serum IgE to airborne allergens and eight P. pratense molecules (rPhl p 1, rPhl p 2, rPhl p 4, rPhl p 5b, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12) were tested by ImmunoCAP FEIA.

RESULTS

The analysis of IgE responses against eight P. pratense molecules showed 87 profiles. According to the number of molecules recognized by IgE, the more complex profiles were characterized by higher serum total IgE, higher grass-specific serum IgE, and higher number and degree of sensitization to pollens. The most frequent IgE sensitization profile was the monomolecular Phl p 1. Sensitization to Phl p 7 was a reliable biomarker of asthma, whereas Phl p 12 of oral allergy syndrome. Sensitization to Phl p 7 was associated with a higher severity of SARg, and complex profiles were associated with longer disease duration.

CONCLUSIONS

In a large pediatric population, the complexity of IgE sensitization profiles against P. pratense molecules is related to high atopic features although useless for predicting the clinical severity. The detection of serum IgE to Phl p 1, Phl p 7, and Phl p 12 can be used as clinical biomarkers of SARg and comorbidities. Further studies in different areas are required to test the impact of different IgE molecular profiles on AIT response.

Endotypes of pollen-food syndrome in children with seasonal allergic rhinoconjunctivitis: a molecular classification

BACKGROUND

Pollen-food syndrome (PFS) is heterogeneous with regard to triggers, severity, natural history, comorbidities, and response to treatment. Our study aimed to classify different endotypes of PFS based on IgE sensitization to panallergens.

METHODS

We examined 1271 Italian children (age 4-18 years) with seasonal allergic rhinoconjunctivitis (SAR). Foods triggering PFS were acquired by questionnaire. Skin prick tests were performed with commercial pollen extracts. IgE to panallergens Phl p 12 (profilin), Bet v 1 (PR-10), and Pru p 3 (nsLTP) were tested by ImmunoCAP FEIA. An unsupervised hierarchical agglomerative clustering method was applied within PFS population.

RESULTS

PFS was observed in 300/1271 children (24%). Cluster analysis identified five PFS endotypes linked to panallergen IgE sensitization: (i) cosensitization to ≥2 panallergens ('multi-panallergen PFS'); (ii-iv) sensitization to either profilin, or nsLTP, or PR-10 ('mono-panallergen PFS'); (v) no sensitization to panallergens ('no-panallergen PFS'). These endotypes showed peculiar characteristics: (i) 'multi-panallergen PFS': severe disease with frequent allergic comorbidities and multiple offending foods; (ii) 'profilin PFS': oral allergy syndrome (OAS) triggered by Cucurbitaceae; (iii) 'LTP PFS': living in Southern Italy, OAS triggered by hazelnut and peanut; (iv) 'PR-10 PFS': OAS triggered by Rosaceae; and (v) 'no-panallergen PFS': mild disease and OAS triggered by kiwifruit.

CONCLUSIONS

In a Mediterranean country characterized by multiple pollen exposures, PFS is a complex and frequent complication of childhood SAR, with five distinct endotypes marked by peculiar profiles of IgE sensitization to panallergens. Prospective studies in cohorts of patients with PFS are now required to test whether this novel classification may be useful for diagnostic and therapeutic purposes in the clinical practice.

Neuroimaging is useful for monitoring disease activity in linear scleroderma "en coup de sabre"

Scleroderma is a group of rare chronic connective tissue disorders characterized by collagen accumulation that causes tissue hardening with consequent fibrosis. Skin involvement is mostly frequent, although several internal organs can be impaired (heart, lungs, liver, etc.). In childhood, juvenile localized scleroderma (JLS) is more frequently observed; in this subtype cutaneous lesions predominate frequently on the limbs but also on the face and scalp; in this case, it is referred to as scleroderma "en coup de sabre" (ECDS). Neurological abnormalities have been described in association with ECDS as an effect of progressive scalp and underlying tissues involvement. Up to now, no validated biomarkers exist to evaluate disease evolution and, in this way, frequently diagnosis of central nervous system (CNS) involvement occurs when patients are already symptomatic. We describe the case of a 5-year old girl, with a diagnosis of ECDS characterized by the typical scalp lesion, with slight subsidence of the underlying diploe. In this case, radiological examination has been essential to evaluate the degree of progression of skin and soft tissues lesions and to clarify the right therapeutic approach. In selected JLS children, both MRI and CT with 3D reconstruction images provide a useful tool to monitor disease evolution and to address therapeutic choices.

Anti-infective prophylaxis for primary immunodeficiencies: what is done in Italian Primary Immunodeficiency Network centers (IPINet) and review of the literature

Primary immunodeficiencies (PIDs) are rare diseases characterized by an increased susceptibility to infections. Early diagnosis and appropriate treatment are critical for reducing morbidity and mortality. Based on available data, the efficacy of antibiotic administration for the prophylaxis of infections remains uncertain, and recommendations supporting this practice are poor. The use of antimicrobial prophylaxis is mainly based on single institution-specific experience without controlled measurements of patient safety and quality health outcomes. To address this issue an Italian Network on Primary Immunodeficiencies (IPINet) has been set up in 1999 within the Italian Association of Pediatric Hematology and Oncology (AIEOP) to increase the awareness of these disorders among physicians. Further, diagnostic and treatment guideline recommendations have been established to standardize the best clinical assistance to all patients, including antibiotic prophylaxis, and for a national epidemiologic monitoring of PIDs. The aim of this review is not only to give a scientific update on the use of antimicrobial prophylaxis in selected congenital immunological disorders but also to draw a picture of this practice in the context of the Italian Primary Immunodeficiency Network (IPINet). Controlled multicenter studies are necessary to establish if, when and how you should start an efficacious antimicrobial prophylaxis.

Immune responses to tetanus vaccination in Italian healthy subjects and children with recurrent infections

The ability of vaccine antigen to generate protection is a challenge that cannot be restricted to the antibody response; however, the contribution of T cell-mediated mechanisms has not been extensively analyzed. Age and administration to specific categories of patients, i.e. children with recurrent infections (RI), are some of the factors that might affect the vaccine immune response. We investigated the humoral and cellular response to tetanus toxoid (TT) vaccine in 104 healthy children (HC), 11 newborns and 22 healthy adults to characterize the status of immunity according to age and compared it to 118 RI children. Humoral and cellular responses varied in both groups according to age and doses of TT administered. The prevalence of antibody and cellular response was similar in both cohorts (HC 88 percent and 82 percent versus RI 86 percent and 85 percent), however, TT antibody values were significantly higher in 12-18 months old RI children compared to HC (median: 5 IU/ml vs 1.10 IU/ml) (p = 0.02). The lack of an efficient immune response was observed in 12-15 percent of children from both cohorts. Our data showed that specific antibodies were responsible for early protection, whereas cell-mediated mechanisms may contribute to the generation of long-term immunity after an appropriate vaccine recall. The occurrence of higher TT antibody values in 12-18 months old RI children deserves additional research to determine whether they are caused by different infectious agents and/or by other environmental factors. Clarification of this issue is important for categorizing patients into an optimal vaccine policy.

Lack of Systemic Side Effects of Long-Term Inhaled Fluticasone Propionate Use in a Cohort of Asthmatic Children

Inhaled corticosteroids (ICS) are established as first-line therapy for persistent asthma in children. Fluticasone propionate (FP) has been used because it has equivalent efficacy when used at half-dose of older-generation ICS and has a comparable safety profile. However, concerns persist about the potential risk of adverse effects of long-term FP therapy on childhood growth, bone, adrenal function and immune system. To evaluate the potential adverse effects of FP, we analyzed growth, glucidic metabolism, hypothalamic-pituitary-adrenal axis, bone metabolism, bone mass density and immune system in a cohort of 19 children (average 102±18 months), with asthma who were in treatment with FP (average duration: 14 months, range: 11–17 months). Of these, 11 children homogenous for control of asthma symptoms, and compliance to therapy, were selected for a prospective study during which they were treated with FP250 mg/day for further 6 months (total period of treatment average duration: 22 months, range: 18–23 months). In all children, no alterations of growth, glucidic metabolism, hypothalamic-pituitary-adrenal axis, bone metabolism, bone mass density, immune system nor severe exacerbation of the disease were observed. Our study, showing that FP was able to control the symptoms of asthma and confirming the lack of systemic side effects at the recommended doses, supports its long-term use in children with asthma.

Happy Air: a school-based educational program to maximize detection of asthma in children

OBJECTIVE

To investigate whether an active partnership among school, parents, and pediatricians allows early identification and treatment of asthmatic children.

METHODS

An asthma educational program (Happy Air), based on a strong family-physician-school interrelationship, was performed in six primary schools (2,765 children) before administering a screening questionnaire to the parents.

RESULTS

A high response rate (96%) demonstrated 2,649 responders available for the asthma screening: 135 children (5%) received a diagnosis of asthma, of which 37 (27%) were recognized de novo.

CONCLUSION

The active participation of school and parents is the determining factor for the success of an asthma screening program.

A Prospective Study on Children with Initial Diagnosis of Transient Hypogammaglobulinemia of Infancy: Results from the Italian Primary Immunodeficiency Network

Transient hypogammaglobulinemia of infancy (THI) is a heterogenous disorder characterized by reduced serum IgG levels in early infancy. A putative diagnosis is initially made after exclusion of other causes of hypogammaglobulinemia while a definitive diagnosis of THI can only be made a posteriori in patients with normalization of IgG levels. The aim of this study is to characterize clinical and immunological features of children with an initial diagnosis of THI in correlation to natural outcome, and to assess predictive laboratory parameters of clinical evolution for this disorder. We prospectively analysed clinical and immunological characteristics of 77 THI children at initial diagnosis and of 57 patients at follow-up. Memory B cell subsets and in vitro immunoglobulin production were evaluated. Seventy patients (91%) showed clinical symptoms. Patients suffered from infections (91%), allergies (47%) and autoimmune disease (4%). During follow-up 41/57 children (72%) normalized IgG values, mostly within 24 months of age (p<0.001), allowing the diagnosis of THI. The 16 children who did not normalize their IgG levels showed a higher frequency of severe infections and autoimmune disease (p<0.01). Moreover, they expressed a reduced frequency of IgM and switched memory B cells (p<0.01) and an inability to produce IgG in vitro (p<0.02). We conclude that most patients with an initial diagnosis of THI spontaneously recover within 24 months of age and have a benign clinical course, while a subgroup of children with undefined hypogammaglobulinemia share a clinical and immunological profile with other primary immunodeficiencies. Early recognition of children with hypogammaglobulinemia during infancy who are likely to suffer from permanent immunodeficiencies later in life would allow prompt and appropriate laboratory and clinical interventions.

Insight into B cell development and differentiation

The main topic of this article is B cell development and differentiation, with a special focus on the mechanisms and molecules that regulate the expression of humoral immunity. Molecular epidemiological analysis was performed on the genes responsible for the X-linked agammaglobulinemia (XLA) phenotype of the majority of Italian patients and their distinct mutations were characterized. Mutations in Bruton's tyrosine kinase (BTK), a member of Tec Family of protein tyrosine kinases, have been found to be mainly responsible for XLA disease. The exact function of BTK in signal transduction is not yet known; thus, the specific role of BTK in receptor-dependent calcium signaling and the pro-antiapoptotic regulatory activity was addressed by transfecting RAMOS-1, a BTK-deficient human Burkitt's/B cell leukemia line with wild-type and mutant constructs. This work may provide clues about critical sites in the molecule and give support for gene therapy as a potential successful approach to XLA. Another aspect of this research is the identification and dissection of the molecular events that are likely to be directly related to the ability to express various isotypes of immunoglobulin with differing function and certain B cell immunodeficiency, mainly common variable disease and non-X-linked hyperIgM. B cell development and maturation steps in different compartments of the immune system are tracked by the analysis of cell-surface molecules and components of the signal transduction pathways, i.e. CD40, CD30, CD27, CD38, CD22 and CD24. A few components involved in B cell development, maturation and differentiation and their specific functional role are at least partially known, but these are far from fitting into an understandable pathway at present.

Bruton's tyrosine kinase defect in dendritic cells from X-linked agammaglobulinaemia patients does not influence their differentiation, maturation and antigen-presenting cell function

X-linked agammaglobulinaemia (XLA) is a primary immunodeficiency disease characterized by very low levels or even absence of circulating antibodies. The immunological defect is caused by deletions or mutations of Bruton's tyrosine kinase gene (Btk), whose product is critically involved in the maturation of pre-B lymphocytes into mature B cells. Btk is expressed not only in B lymphocytes but also in cells of the myeloid lineage, including dendritic cells (DC). These cells are professional antigen presenting cells (APC) that play a fundamental role in the induction and regulation of T-cell responses. In this study, we analysed differentiation, maturation, and antigen-presenting function of DC derived from XLA patients (XLA-DC) as compared to DC from age-matched healthy subjects (healthy-DC). We found that XLA-DC normally differentiate from monocyte precursors and mature in response to lipopolysaccharide (LPS) as assessed by de novo expression of CD83, up-regulation of MHC class II, B7.1 and B7.2 molecules as well as interleukin (IL)-12 and IL-10 production. In addition, we demonstrated that LPS stimulated XLA-DC acquire the ability to prime naïve T cells and to polarize them toward a Th1 phenotype, as observed in DC from healthy donors stimulated in the same conditions. In conclusion, these data indicate that Btk defect is not involved in DC differentiation and maturation, and that XLA-DC can act as fully competent antigen presenting cells in T cell-mediated immune responses.

X-chromosome inactivation and mutation pattern in the Bruton's tyrosine kinase gene in patients with X-linked agammaglobulinemia. Italian XLA Collaborative Group

BACKGROUND

The diagnosis of X-linked agammaglobulinemia (XLA) is not always clearcut. Not all XLA conform to the classic phenotype and less than 50% of affected boys have a family history of immunodeficiency. Mutations in the gene for Bruton's tyrosine kinase (BTK) are responsible for the majority of agammaglobulinemia cases. However, a certain proportion of patients may have mutations involving other genes, although they show with an XLA phenotype. We performed BTK gene mutation analysis in 37 males with presumed XLA and analyzed the pattern of X-chromosome inactivation (XCI) in 31 mothers to evaluate the relevance of these approaches to diagnosis and genetic counseling.

MATERIALS AND METHODS

Twenty affected males with a sporadic occurrence and 17 familial cases belonging to nine families were enrolled within the framework of the Italian Multicenter Clinical Study on XLA. We used non-isotopic RNase cleavage assay (NIRCA), followed by cDNA sequence determination to screen for BTK mutations and X-chromosome inactivation analysis for carrier detection.

RESULTS

Using the cDNA-based approach, the identification of BTK gene abnormalities confirmed the clinical diagnosis of XLA in 31 of 37 affected infants. Missense was the most frequent mutational event and the kinase domain was mostly involved. In addition, nine novel mutations were identified. In sporadic cases, BTK gene abnormalities were identified in 9 out of 10 patients whose mothers had a nonrandom pattern of XCI and in 5 out of 6 patients whose mother had a random pattern of XCI. With the exception of one family, all patients with a familial occurrence and born to mothers with a nonrandom pattern of XCI had mutations of the BTK gene.

CONCLUSIONS

Our findings indicate that in sporadic cases BTK gene sequencing is the only reliable tool for a definitive diagnosis of XLA and support XCI as the first diagnostic tool in the mothers of affected males in multiple generations. Furthermore, our molecular analysis confirms that 10-20% of BTK-unaltered patients have disorders caused by defects in other genes.

Identification of nine novel mutations in the Bruton's tyrosine kinase gene in X-linked agammaglobulinaemia patients

Mutations in the Bruton's tyrosine kinase (BTK ) gene are responsible for X-linked Agammaglobulinemia (XLA), an immunodeficiency caused by a block in B cell differentiation. Non Isotopic RNAse Cleavage Assay (NIRCA), followed by sequencing was used to screen for BTK mutations in 11 Italian XLA patients. Nine novel mutations were identified: 6 missense (Y39S, L512P, L512Q, R544G, S578Y, E589K), one non-sense (Q260X), one frameshift (1599-1602del GCGC) and one in-frame insertion (2037-2038insTTTTAG), that represents the first case of premature stop codon introduction in the BTK coding frame. These data support the high molecular heterogeneity of BTK gene in XLA disease and provide new insight to the diagnosis and to the role of BTK domain in XLA and in B cell signal transduction and development. Hum Mutat 15:117, 2000.

Absence of Bruton's tyrosine kinase (Btk) mutations in patients with acute myeloid leukaemia

Bruton's tyrosine kinase (Btk) is a non-receptor protein tyrosine kinase (PTK) that is expressed in all haemopoietic lineages except mature T cells and plasma cells. Despite the broad range of expression. mutations that inactivate this molecule affect primarily the development of the B-cell lineage. As a PTK, Btk could potentially be involved directly or indirectly in the processes that relate to the malignant transformation of all the cell lineages where this molecule is expressed. Previous studies have failed to demonstrate mutations in patients with B-cell origin acute lymphoblastic leukaemia (ALL). We have utilized a recently developed method that enables the rapid and convenient detection of mutations at the cDNA level, namely, the non-isotopic RNase cleavage assay (NIRCA) to analyse Btk sequences from 27 patients with different types of acute myeloid leukaemia (AML). The only alteration that we observed was a polymorphism at position 2031. This polymorphism has already been seen in previous studies. Furthermore, using the same methodology, we identified the Btk mutations in six XLA (X-linked agammaglobulinaemia) patients. Our results, although they do not exclude the involvement of Btk mutations in the development or progression of some type of AML, nevertheless suggest that such mutations do not constitute a major co-factor in the development of myeloid malignancies.

Role of immunity in maternal-infant HIV-1 transmission

Factors influencing human immunodeficiency virus type 1 (HIV-1) mother-to-child transmission include both immunological and virological parameters: higher viral loads have been associated with clinical stage of HIV-1-infected individuals as well as higher risk of mother-to-child transmission. Furthermore, we have shown that transmitting mothers more frequently harbour HIV-1 isolates with rapid/high syncytium-inducing (SI) biological phenotype than non-transmitting mothers do. Genetically homogeneous virus populations have been found in HIV-1-infected children at birth, in contrast to the heterogeneous virus populations often found in their infected mothers. This observation suggests that a few virus variants are transmitted or initially are replicating in the child. By comparing the HIV-1 gp120 V3 region of sequentially obtained samples from infected children with samples obtained from their mothers at delivery we found, however, that multiple variants of HIV-1 with different outgrowth kinetics can be transmitted. In addition, we have obtained results indicating an impaired ability of the immune response to adapt to the sequence evolution of HIV-1 in transmitting mothers, as assessed by measuring serum reactivities to peptides representing selected yet closely related V3 sequences. By analysing the presence of antibodies in maternal serum at delivery, which neutralize autologous isolates as well as other primary virus isolates, we have indications that a protective immunity in HIV-1 mother-to-child transmission might exist. Immunotherapy has been assessed in infected adult individuals by passive immunization with a variety of HIV-1-specific antibody products. Data from these studies indicated a differential response to therapy according to the stage of the disease. Active vaccine strategies, including envelope glycoproteins, pursued so far in seronegative adult subjects have shown limitations because broadly neutralizing antibodies, such as can be found in infected individuals, have not been evoked. Further investigations are therefore needed to give support for the potential use of either passive and/or active immunization for the prevention of HIV-1 mother-to-child transmission.

[Clinical comparison of different replacement milk formulas in children with allergies to cow's milk proteins. 24-month follow-up study]

The elective treatment for allergy to cow's milk protein is the elimination of these proteins from the diet. The present study with a follow-up of over two years took the form of a comparison between different replacement formulas based on soya (group A), hydrolysate of soya and bovine collagen (group B), and hydrolysate of casein (group C), randomly administered to 55 children (30 males and 25 females, aged between 2-48 months) with documented allergy to cow's milk proteins, but with different clinical symptoms. Tests to evaluate the acquisition of clinical tolerance to cow's milk proteins were performed using a day-hospital regime every 6 months. Sensitivity reactions were observed in 22% of cases in group A, 8% in group B and 37.5% in group C. It is worth underlining that 5 of the 6 children with reactions to soya protein then showed an excellent tolerance to hydrolysate of soya when it was administered subsequently until tolerance was achieved. Weight and statutory growth was uniformly good in all three groups. A high percentage of children achieved tolerance after 24 months (72%); the mean time taken to acquire clinical tolerance was 11.6 +/- 4.8 in group A, 11.6 +/- 6.02 in group B, and 14 +/- 5.6 in group C. No correlation was found between the type of initial symptoms, age at onset, method of response to first challenge and the time taken to acquire tolerance.

Analysis of polyunsaturated fatty acids in newborn sera: a screening tool for atopic disease?

It has been demonstrated that patients with atopic disease have anomalies of fatty acid composition, as a result of altered metabolism or abnormal incorporation of fatty acids into the tissues. In the present study, in 57 newborns 'at risk' for atopic disease, the polyunsaturated fatty acid (PUFA) levels were found to be lower in cord blood in infants who subsequently developed atopic disease than in non-atopics. In all babies, levels of arachidonic acid and dihomo-gamma-linolenic acid in sera at 1 and 3 months of age were lower than those in cord blood. These changes were more marked in children who subsequently developed atopic disease, and in those who, independently of signs and/or symptoms of atopic disease, were formula-fed. A comparison between IgE and PUFA levels revealed no significant differences at any tested time interval. In conclusion, our data suggest that in children 'at risk' for atopy, PUFA levels may be predictive of atopic disease.

Methylprednisolone bolus: a novel therapy for severe atopic dermatitis

Seven children suffering from severe atopic dermatitis, unresponsive to standard therapy, received an iv bolus dose of methylprednisolone (20 mg/kg/day) for three days. Immunological parameters were evaluated before and after treatment. At the end of bolus therapy both skin lesions and itching improved for several months in five of seven patients. No side effects were observed, but a significant and transient lymphopenic response occurred, with lower CD4+ than CD8+ lymphocyte counts. Our data suggest that this therapy may be a novel and safe therapeutic approach in severe atopic dermatitis.

Use of a specific oral hyposensitization therapy to Dermatophagoides pteronyssinus in children with atopic dermatitis

The aim of the present study was to evaluate the efficacy of an oral specific hyposensitization therapy in children with atopic dermatitis and positive prick skin tests and/or RAST to Dermatophagoides pteronyssinus (D.pt.). A total of 60 patients, in three different clinical groups, were selected for a three years clinical trial. Group A: children with atopic dermatitis and allergic asthma and/or rhinitis; groups B and C: children with exclusively atopic dermatitis. Groups A and B received specific hyposensitization therapy. Group C was the control group. The clinical evaluation of the dermatological lesions, at the end of our study, didn't show any significant difference among the three groups. Moreover, the onset of respiratory symptoms between the two groups with exclusively atopic dermatitis was similar and not related to the positivity of prick skin tests and/or RAST to seasonal allergens. Our study suggests that specific hyposensitisation therapy with extracts of D.pt., although with no side effects, does not affect the natural history of atopic dermatitis.

Antibody-dependent cellular cytotoxicity and neutralizing activity in sera of HIV-1-infected mothers and their children

The prognostic and protective role of antibodies mediating cellular cytotoxicity (ADCC) and neutralization was evaluated in sera of HIV-1-infected mothers and their consecutively followed children. The presence and titres of ADCC mediating and/or neutralizing antibodies in maternal sera did not predict HIV-1 infection in their respective children. No significant difference in the sera from the children was seen when comparing the presence of neutralizing antibodies between the uninfected and infected children. Stratification of the infected group according to clinical status revealed differences. Only one of 24 AIDS patients had a high neutralizing titre against IIIB. Four patients had a very low titre and the remaining had no detectable neutralizing antibodies at all. In contrast, 10/17 infected non-AIDS children had neutralizing antibodies. Similarly, no significant difference was seen when comparing the presence of ADCC-mediating antibodies between the uninfected and the infected group of children. However, a significantly higher frequency of ADCC was seen in the seropositive non-AIDS children compared with the AIDS children. This study clearly shows that the presence of antibodies mediating ADCC and neutralization in infected children, 0-2 years old, is associated with a better clinical status and delayed disease progression.

Detection of antibodies to human immunodeficiency virus type I by using synthetic peptides and time-resolved fluoroimmunoassay (TR-FIA)

A simple, rapid, reproducible and sensitive peptide-Time-Resolved-Fluoroimmunoassay (TR-FIA) method is described which allows the detection of antibodies to the Human Immunodeficiency Virus type 1 (HIV-1). By using a panel of synthetic peptide antigens that covered env, gag and pol amino acid sequences, a 20 amino acid peptide (GIWGCSGKLICTTAVPWNAS) describing an immunodominant and conserved domain on the gp41 region of the BH10 clone was found to be the most reactive in this study. Optimal conditions for antigen concentration, serum dilution and incubation time were established. The peptide-TR-FIA is specific, as assessed by testing HIV-1 positive sera which included samples from AIDS, ARC patients and HIV-positive drug users. The test was used to detect HIV antibodies in 250 well characterized HIV-1 positive sera and 50 normal sera. Peptide-TR-FIA results indicate that the env peptide was highly reactive with HIV-positive sera showing a sensitivity of 100%. None of the 50 control sera showed positive reactivity against the synthetic peptide. Furthermore the peptide-TR-FIA allowed a fine titration of antibodies to defined epitopes of immunodominant HIV structural proteins that usually cannot be achieved by peptide-ELISA assays.

Mother-to-child transmission of human immunodeficiency virus

Transmission of HIV virus from an infected mother to her offspring is becoming the leading cause of spreading in the pediatric population. This is particularly burdensome in the pattern II countries where HIV infection has reached epidemic proportions and infection rates affect more women of childbearing age than men. During the last few years considerable effort has been directed at defining the optimal methods for identifying infants of HIV-infected mothers who will themselves prove to be infected because conventional serological assessment is impaired due to placental transfer of maternal IgG. At present, detection of specific IgA to HIV proteins, evaluation of autochthonous antibody production in vitro from infants' lymphocytes, and gene amplification of HIV DNA/RNA by polymerase chain reaction are the most promising procedures for early diagnosis within the first 6 months of life. Nevertheless all these techniques are cumbersome when evaluating specimens from the newborn child. Many studies have been performed to identify those maternal factors affecting the risk of vertical transmission. So far, none of them has shown real prognostic value. However, evaluation of maternal antibody response to functional epitopes of HIV envelope proteins such as the principal neutralizing domain, in some epidemiological settings, seems to correlate to a reduced rate of mother-to-child transmission.

Antibodies mediating cellular cytotoxicity and neutralization correlate with a better clinical stage in children born to human immunodeficiency virus-infected mothers

In children born to human immunodeficiency virus (HIV)-infected mothers, factors that determine disease outcome and progression are unclear. Also, early diagnosis is hampered by maternally transferred antibodies. Children aged 0-24 months were retrospectively divided into two groups based on HIV seroreactivity or nonreactivity at age 15 months and analyzed for the presence of antibodies that mediate cellular cytotoxicity (ADCC) and virus neutralization. No difference was seen in the presence of these functional antibodies between groups. The persistently seropositive group was further divided into non-AIDS and AIDS groups according to clinical status at serum collection. The ADCC antibody frequencies were much higher (70%) in the non-AIDS group than in the AIDS group (30%). Of the non-AIDS children, 63% had neutralizing antibodies; no children with AIDS had these antibodies. HIV-specific ADCC and neutralizing antibodies do not seem to protect against transmission of HIV from mother to child but are significantly correlated with a better clinical stage of childhood HIV infection.

Presence of maternal antibodies to human immunodeficiency virus 1 envelope glycoprotein gp120 epitopes correlates with the uninfected status of children born to seropositive mothers

The present study demonstrates that maternal antibodies to certain epitopes of human immunodeficiency virus 1 (HIV-1) proteins are associated with a defined outcome for at-risk pregnancies of HIV-infected women. An initial retrospective analysis of antibodies to synthetic peptides and recombinant proteins representing env, pol, and gag regions of HIV-1 was carried out. Sera studied were from 33 children who were born to HIV-infected mothers and whose clinical outcome was known at the time of analysis. Sera, collected within the first 6 months of life, of uninfected at-risk children were found to selectively contain maternal antibodies to certain peptides containing epitopes of the HIV envelope glycoprotein gp120. To confirm the predictive role of maternal antibodies to defined HIV-1 epitopes, a prospective analysis was then performed on sera from 21 HIV-seropositive mothers and their infants, whose clinical and immunological status was then followed up for a period of at least 15 months. As expected, antibodies to the same envelope protein peptides were detected almost exclusively in sera from mothers of uninfected children. Our data suggest that antibodies against select epitopes of HIV envelope protein gp120 might play an important role in preventing mother-to-child transmission of HIV-1 infection. Accordingly, site-directed serology might be used to predict the outcome of an at-risk pregnancy of an HIV-infected woman.

Diagnostic implication of specific immunoglobulin G patterns of children born to HIV-infected mothers

We analysed HIV-specific immunoglobulin G (IgG) responses to gag and env peptides in infants born to HIV-positive mothers. Questions of interest were whether there are early specific markers for prognosis, and whether any specific IgG is related to the prevention of vertical transmission of infection. Fifty-three children, 0-24 months old and born to HIV-1-infected mothers, were retrospectively divided into two groups based on HIV seroreactivity or non-reactivity at 15 months of age. Their sera were used to find reactivities important in diagnosis and/or prediction of the putative HIV disease. Three important findings emerged. First, a low IgG titer against the very immunodominant penv9 in newborns was found to be associated with rapid progression to AIDS. This difference was clearly reflected in the reactivity to a small peptide representing amino acid (aa) 598-606. The second interesting finding was the putative hypervariable loop on gp120 (especially aa 324-338), reactivity to which was found only in the uninfected group, and was seen in six out of 19 uninfected children under 6 months of age. This specific response was not caused by a generally high total anti-HIV reactivity, and may indicate a role of protective antibodies against vertical transmission. The response to this region in the infected group, on the other hand, was directed to the amino terminal half of the putative loop, in particular peptide 53, aa 304-318. Finally, response to a part of the amino terminal end of P17 was seen in seven out of eight infected children over 6 months of age.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV viral sequences in seronegative people at risk detected by in situ hybridisation and polymerase chain reaction

A study was conducted to assess the occurrence of latent infection with the human immunodeficiency virus (HIV) among seronegative people at high risk of infection. The presence of HIV genomes was analysed by molecular techniques in two seronegative children born to mothers infected with HIV and in three regular sexual partners of seropositive drug addicts. The adults were selected from a seronegative cohort at high risk of infection because of their sexual contacts and the children selected because of impaired growth. HIV retroviral sequences were detected in four of the five subjects directly at the cellular level by in situ hybridisation in peripheral blood mononuclear cells. HIV genomic sequences were confirmed by in vitro amplification of viral DNA with the polymerase chain reaction technique. The existence of a latent viral infection state in these seronegative subjects indicates the unreliability of standard serological analysis in people who have been in regular contact with infected patients.

Immunological studies in patients with central nervous system tumors

Impairment of cell-mediated immunity in patients with primary central nervous system (CNS) tumors has repeatedly been reported but data to demonstrate the underlying immunological defect are not univocal. This report concerns a series of 31 patients harboring a glioma in which we studied: peripheral blood T-lymphocyte subpopulations by monoclonal antibody analysis; cellular responsiveness to mitogens; serum immunoglobulin values. The same parameters were also evaluated in 7 cases of intracranial meningioma and in 8 patients affected by non-proliferative, non-inflammatory CNS diseases. Thirty age-matched healthy volunteers formed the control group. Neither impairment of T-cells as regard to number, responsiveness and subsets, nor abnormal Ig values were found in these groups. However two patients, harboring respectively a third ventricle low grade astrocytoma and an anterior callosal glioblastoma, presented a striking T-cells impairment. These findings might suggest a correlation between hypothalamus and immune system, as already postulated by several previous experimental and clinical studies.

Leukocyte locomotory function in children with the immotile cilia syndrome

The random motility of polymorphonuclear leucocytes (PMN), cellular chemotaxis and chemokinesis in kinetic fashion in 4 patients with immotile cilia syndrome (ICS) have been evaluated. No impairment of granulocyte ability of orientation and migration was found. Ultrastructural alterations of cilia which are the primary factor in the pathogenesis of respiratory tract disease in patients with ICS do not impair the PMN function.