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Prevention of food allergy in infancy has been the aim of important researches in the last years but many studies have produced conflicting conclusions. The use of hydrolysate formulas seems to be an helpful tool in prevention of cow milk protein allergy but confusion often remains about capability of small hydrolysate molecules to be "allergens" or "antigens". In order to clarify this point IgE, IgG and IgM as well as IgG subclasses against alfa-lactoalbumin (ALA) and beta-lactoglobulin (BLG) have been evaluated in 41 infants at risk for allergy and in 30 controls at the fourth month. The same evaluation has been done on their mothers. The 41 "at risk" children were fed with breast milk or with an hypoallergenic formula (Nidina HA, Nestlè) or both. The control children received an adapted formula. No difference between the two groups of children was found regarding IgM or IgG against ALA while antibodies against BLG were more frequently found in controls than in "at risk" children. Only one child in the group fed with Nidina HA developed specific IgE against whole milk. Therefore hydrolysate formula seems to be as antigenic (not allergenic) as adapted formula in respect of ALA while BLG contained in adapted formula seems to be a stronger immunogen. The pattern of specific IgG subclasses against ALA and BLG is different between the two groups of children because of the absence in "at risk" group of specific IgG2 and IgG3. As for the mothers, the presence in their sera of IgG against ALA or BLG seems to induce in infants a reduced response to the same antigen.

The prevalence of gastroesophageal reflux (GER) in 86 children with respiratory disease (recurrent pneumonia, chronic cough, bronchial asthma) has been evaluated by mean of prolonged (22-24 hours) esophageal pH-monitoring. The following parameters were evaluated: the total percentage of time pH < 4 and the percent time the esophageal pH was < 4 while sleeping. None of the children had gastrointestinal symptoms suggesting GER and no neurological disorder was noted in any of the studied patients. The mean age was 68.98 +/- 46.46 months (range 14-189); 53 (61.6%) males and 33 (38.4%) females were considered in the study. Atopy was evidenced in 42/86 (48.8%) children (total IgE > 2SD in 42/86 and prick tests positiveness in 32/86. A pH-metry indicating pathological GER was present in 52/86 (60.5%) children: 39/62 (62.9%) patients with bronchial asthma, 5/10 (50%) subjects with chronic cough and 8/14 (57.2%) children with recurrent pneumonia. No significant difference in the diagnosis of GER was recorded between atopic or non-atopic patients. The children with abnormal pH-metric recording were also evaluated by upper gastrointestinal series and/or endoscopy. A conventional barium radiology was performed in 44/52 patients and confirmed GER in 19/44 (43.2%). Esophagitis was evidenced in 21/46 (45.7%) studied patients. The presence of esophagitis was significantly (p = 0.032) related to the total percentage of time pH < 4, but the most significant (p = 0.002) association was with the percent time the esophageal pH was < 4 during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory infections are the major cause of disease in childhood in the industrialized areas of the world. This essentially depends on two factors: immunological immaturity and immunological naivety. In most cases a virus has been considered the causative agent in respiratory infection. A defect in immune responses has been described in children with recurrent respiratory infections and in particular a decrease in CD4/CD8 T lymphocyte ratio or in IL-2 and IFN-gamma production. Our results show that Natural Killer (NK) cell activity is defective in children with recurrent respiratory infections. That is particularly noteworthy since NK cells play an important role in host defense against viral infections. At present it is difficult to understand whether the NK defect is a primary defect or it is secondary to viral infections. Further studies will help to clarify whether NK decreased activity depends on a cell damage directly caused by virus or it depends on the decreased levels of cytokines.

Hepatitis B virus (HBV) is one of the most important causes of chronic liver disease. HBV is a DNA virus with an external glycoprotein surface and an internal nucleocapsid which contains the viral genome. HBV infection is revealed by the appearance of specific markers. Some of these markers are well known and their presence in serum is important to understand the behaviour of the disease. Among them HBsAg, HBeAg, anti-HBs and anti-HBe are found in serum, so as anti-Core; the HBcAg may be found in hepatic tissue and marks infectivity and virus replication. In the few last years some new antigens and antibodies have been studied and their importance in diagnosis and follow-up of hepatitis has been recognized. HBxAg, Pre-S and DNA-Polymerase (Pol) seem to be specific and early signals of viral replication. More studies showed the trans-activating properties of HBxAg; actually the X protein seems to be involved in replicative cycle of HBV. Many Authors also demonstrated a relationship between the presence of X in serum and/or liver and the progression of disease to cirrhosis and hepatocellular carcinoma. The Pol antigen and its antibody seem to be very common markers of HBV infection in serum of patients with hepatitis. Moreover their presence is the only signal of viral infection in some patients which have no other marker of HBV. More studies are of course needed to exactly establish the significance of these new markers and their importance for diagnosis and prognosis of HBV infection.

B-cell dysfunction in HIV-infected children is reflected by hypergammaglobulinemia and high levels of serum IgA. Little is known about antibody specificity since only a small portion of serum IgA appears to be directed against HIV proteins. In the present study the specificity of IgA antibodies against food, inhalant, bacterial and fungi antigens were evaluated in a population of HIV infected children. ELISA method was used for antibody testing. Our results show that in 84.6% of patients IgA against at least one food antigen are present. IgA against inhalant allergens were present in most of HIV-infected children but in none of controls. As for anti-tetanus toxoid antigens and anti-fungi antigens, though present in higher percentage in patients, specific IgA were found also in healthy children. If a gastrointestinal dysfunction might be supposed as the cause of presence of anti-food antigen IgA, it is difficult to consider this factor as the cause of presence of specific IgA directed against different antigens. It is possible to postulate that an immunologic dysregulation based on an imbalance between Th1 and Th2 cells or on higher levels of IL-5 and/or IL-6 may lead to a misfunction of B cell and consequently to hypergammaglobulinemia with high IgA levels.

Substance P (sP) and Somatostatin (SOM), so as other neuropeptides can modulate neurologic and immunologic functions. sP has been described to enhance both in vitro and in vivo immunoglobulin synthesis. On the contrary, SOM has an inhibitory effect on the same activity. The modulating effect is more evident on IgA isotype. Hypergammaglobulinemia and in particular high levels of IgA is a common finding in pediatric AIDS and an imbalance among regulatory effects of neuropeptides might be suggested. In order to evaluate the plasma levels of sP in pediatric AIDS we studied 15 children with HIV infection (status P2), 10 seronegative children born to HIV positive mothers and 10 healthy children of the same age. All the HIV positive children had high plasma levels of IgG and IgA. The plasma level of sP was extremely higher in HIV positive children while no significant difference was found between seronegative children born to HIV positive mothers and healthy children. SOM was decreased in HIV positive children when compared to control groups but a significant difference was not reached. It might be supposed that HIV infection, through a dysregulation among neuropeptides interferes on immune functions and in particular on IgA synthesis. On the other hand it might be suggested that the imbalance between sP and SOM depends on the viral infection of immune cells since it has been demonstrated that SOM and other neuropeptide are synthesized by lymphoid tissue. Further studied relevance of neuropeptide disorders in pediatric AIDS.

The most important symptoms caused by food additives are urticaria and angioedema, but rhinitis, asthma and gastrointestinal disturbances are also reported. Only seldom food additives have been shown to induce symptoms in other organs such central nervous system or joints and with a sparse objective evidence. In this study, we report two cases of unusual reactions to food additives (tartrazine and benzoates) involving mainly the central nervous system (headache, migraine, overactivity, concentration and learning difficulties, depression) and joints (arthralgias), confirmed with diet and double blind challenge. The possible pathogenetic mechanisms are also discussed.

In the last years the research on viral hepatitis let to better understand the biological, molecular, immunological and epidemiologic characteristics of the viruses that are responsible for hepatitis. The first studied virus was hepatitis B virus (HBv). The scientific attention is still, today, focused on that virus since new markers of infectivity and biological importance in early diagnosis and in disease evolution have been found. The most important result in the last years in the field of viral hepatitis has been, however, the identification of agents responsible for Non-A-Non-B hepatitis. Its epidemiology and clinical importance are discussed in the present paper. Virus C is the most important parenteral agent of NANB hepatitis. Its epidemiology in at risk populations and its role in post-transfusional and cryptogenetic hepatitis are here discussed. The research of new markers of HCV infection is today considered a main goal since the role of the only marker now available is still under discussion.

The IgG subclasses are known to have different structure and functions. The IgG1 and IgG3 bind to monocyte and neutrophils and activate the complement more easily then IgG2 and IgG4. The levels of IgG subclasses found in newborns are mainly determined by the transplacental passage since the synthesis, in the first time of life, is very low. The levels found in adults are reached only during the adolescence. The immune response to a protein antigen is mainly in the IgG1 subclass, on the contrary the response to polysaccharide antigens is mainly IgG2. For that reason children, who produce very few IgG2 till they are 2 years old, cannot be vaccinated with carbohydrate vaccines unless a protein conjugate vaccine is used. In addition, the route of subministration, the dose of antigen, the age of vaccinated people and genetic factors can modify the subclass pattern obtained in response to vaccinations. For these reasons, probably, the immune response studied after a vaccination or in individuals who recovered from a natural disease is not always the same. Since the role of the different subclasses is not yet completely clarified, the interpretation of the importance of a selective "choice" of a subclass instead of another after vaccination is still difficult.

Infants born to HBsAg-positive mothers are at high risk of contracting perinatal hepatitis B infection. The prevention is based on active as well as passive immunoprophylaxis. We have used hepatitis vaccine in 18 newborns of as many HBsAg-positive mothers. Some haematologic and immunologic parameters are here reported. No alterations were observed as to liver function. Immunoglobulin values were normal for age. Auto-antibodies and rheumatoid factor were constantly absent. Immunecomplexes were present in the serum of some infants. The study of T cell subsets and of natural killer cells activity did not reveal any important changes, whereas minor modifications were present in polymorphonuclear leucocyte function. In all infants submitted to vaccination serum conversion was observed a with different antibody levels.

This review will describe the current state of basic knowledge on the acquired immune deficiency syndrome (AIDS), which has now spread worldwide becoming an acute public health problem in western countries and in Africa. AIDS is a viral infection, due to a retrovirus designated human immune deficiency virus (HIV), which affects the immune system resulting in a wide array of secondary manifestations which include opportunistic infections, neoplasia, autoimmune phenomena, neurologic disorders, and hematologic abnormalities. AIDS has now been recognized in the pediatric population, and infection occurs by perinatal and blood-borne transmission. As a consequence, pediatricians are no more involved only by a theoretical point of view (AIDS is a perfect model of interaction of virus with the immune system), but also by an operative point of view. Knowledges on immunological modifications in AIDS and on the underlaying features of the HIV are essential for the clinical approach. This goal may be difficult, if one considers that the pace of research in AIDS and the progress attained to date are unprecedent. However, clinicians must be aware that the ultimate solution of clinical problems in AIDS exclusively depends on sound basic research.